CSV_XS(3)
okay so welcome to CSV_XS(3), the User Contributed Perl Documentation page for Text::CSV_XS 💖 — bestie, this is the CSV glow-up you didn’t know you needed, and we are keeping every single detail, no cap.
🌸 NAME 🌸
Text::CSV_XS — comma-separated values manipulation routines ✨
✨ SYNOPSIS ✨
# Functional interface
use Text::CSV_XS qw( csv );
# Read whole file in memory
my $aoa = csv (in => "data.csv"); # as array of array
my $aoh = csv (in => "data.csv",
headers => "auto"); # as array of hash
# Write array of arrays as csv file
csv (in => $aoa, out => "file.csv", sep_char => ";");
# Only show lines where "code" is odd
csv (in => "data.csv", filter => { code => sub { $_ % 2 }});
# Object interface
use Text::CSV_XS;
my @rows;
# Read/parse CSV
my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
open my $fh, "<:encoding(utf8)", "test.csv" or die "test.csv: $!";
while (my $row = $csv->getline ($fh)) {
$row->[2] =~ m/pattern/ or next; # 3rd field should match
push @rows, $row;
}
close $fh;
# and write as CSV
open $fh, ">:encoding(utf8)", "new.csv" or die "new.csv: $!";
$csv->say ($fh, $_) for @rows;
close $fh or die "new.csv: $!";💖 DESCRIPTION 💖
Text::CSV_XS provides facilities for the composition and decomposition of comma-separated values. An instance of the Text::CSV_XS class will combine fields into a CSV string and parse a CSV string into fields.
The module accepts either strings or files as input and supports the use of user-specified characters for delimiters, separators, and escapes. Slay. 💅
🦋 Embedded newlines 🦋
Important Note: the default behavior is to accept only ASCII characters in the range from 0x20 (space) to 0x7E (tilde). This means that the fields can not contain newlines. If your data contains newlines embedded in fields, or characters above 0x7E (tilde), or binary data, you must setbinary => 1in the call tonew. To cover the widest range of parsing options, you will always want to set binary.
But you still have the problem that you have to pass a correct line to the parse method, which is more complicated from the usual point of usage:
my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ });
while (<>) { # WRONG!
$csv->parse ($_);
my @fields = $csv->fields ();
}this will break, as the while might read broken lines: it does not care about the quoting. If you need to support embedded newlines, the way to go is to not pass eol in the parser (it accepts "\n", "\r", and "\r\n" by default) and then
my $csv = Text::CSV_XS->new ({ binary => 1 });
open my $fh, "<", $file or die "$file: $!";
while (my $row = $csv->getline ($fh)) {
my @fields = @$row;
}The old(er) way of using global file handles is still supported
while (my $row = $csv->getline (*ARGV)) { ... }🌈 Unicode 🌈
Unicode is only tested to work with perl-5.8.2 and up.
See also BOM.
The simplest way to ensure the correct encoding is used for in- and output is by either setting layers on the filehandles, or setting the encoding argument for csv.
open my $fh, "<:encoding(UTF-8)", "in.csv" or die "in.csv: $!";
or
my $aoa = csv (in => "in.csv", encoding => "UTF-8");
open my $fh, ">:encoding(UTF-8)", "out.csv" or die "out.csv: $!";
or
csv (in => $aoa, out => "out.csv", encoding => "UTF-8");On parsing (both for getline and parse), if the source is marked being UTF8, then all fields that are marked binary will also be marked UTF8.
On combining (print and combine): if any of the combining fields was marked UTF8, the resulting string will be marked as UTF8. Note however that all fields before the first field marked UTF8 and contained 8-bit characters that were not upgraded to UTF8, these will be bytes in the resulting string too, possibly causing unexpected errors. If you pass data of different encoding, or you don’t know if there is different encoding, force it to be upgraded before you pass them on:
$csv->print ($fh, [ map { utf8::upgrade (my $x = $_); $x } @data ]);For complete control over encoding, please use Text::CSV::Encoded:
use Text::CSV::Encoded;
my $csv = Text::CSV::Encoded->new ({
encoding_in => "iso-8859-1", # the encoding comes into Perl
encoding_out => "cp1252", # the encoding comes out of Perl
});
$csv = Text::CSV::Encoded->new ({ encoding => "utf8" });
# combine () and print () accept *literally* utf8 encoded data
# parse () and getline () return *literally* utf8 encoded data
$csv = Text::CSV::Encoded->new ({ encoding => undef }); # default
# combine () and print () accept UTF8 marked data
# parse () and getline () return UTF8 marked data🎀 BOM 🎀
BOM (or Byte Order Mark) handling is available only inside the header method. This method supports the following encodings: utf-8, utf-1, utf-32be, utf-32le, utf-16be, utf-16le, utf-ebcdic, scsu, bocu-1, and gb-18030. See Wikipedia at https://en.wikipedia.org/wiki/Byte_order_mark 🦋
If a file has a BOM, the easiest way to deal with that is
my $aoh = csv (in => $file, detect_bom => 1);All records will be encoded based on the detected BOM.
This implies a call to the header method, which defaults to also set the column_names. So this is not the same as
my $aoh = csv (in => $file, headers => "auto");which only reads the first record to set column_names but ignores any meaning of possible present BOM.
🌟 SPECIFICATION 🌟
While no formal specification for CSV exists, RFC 4180 at https://datatracker.ietf.org/doc/html/rfc4180 (1) describes the common format and establishes text/csv as the MIME type registered with the IANA. RFC 7111 at https://datatracker.ietf.org/doc/html/rfc7111 (2) adds fragments to CSV.
Many informal documents exist that describe the CSV format. “How To: The Comma Separated Value (CSV) File Format” at http://creativyst.com/Doc/Articles/CSV/CSV01.shtml (3) provides an overview of the CSV format in the most widely used applications and explains how it can best be used and supported.
https://datatracker.ietf.org/doc/html/rfc4180https://datatracker.ietf.org/doc/html/rfc7111http://creativyst.com/Doc/Articles/CSV/CSV01.shtml
The basic rules are as follows:
CSV is a delimited data format that has fields/columns separated by the comma character and records/rows separated by newlines. Fields that contain a special character (comma, newline, or double quote), must be enclosed in double quotes. However, if a line contains a single entry that is the empty string, it may be enclosed in double quotes. If a field’s value contains a double quote character it is escaped by placing another double quote character next to it. The CSV file format does not require a specific character encoding, byte order, or line terminator format.
- Each record is a single line ended by a line feed (
ASCII/"LF"=0x0A) or a carriage return and line feed pair (ASCII/"CRLF"="0x0D 0x0A"), however, line-breaks may be embedded. - Fields are separated by commas.
- Allowable characters within a
CSVfield include0x09(TAB) and the inclusive range of0x20(space) through0x7E(tilde). In binary mode all characters are accepted, at least in quoted fields. - A field within
CSVmust be surrounded by double-quotes to contain a separator character (comma).
Though this is the most clear and restrictive definition, Text::CSV_XS is way more liberal than this, and allows extension:
- Line termination by a single carriage return is accepted by default
- The separation-, quote-, and escape character(s) can be any ASCII character in the range from
0x20(space) to0x7E(tilde). Characters outside this range may or may not work as expected. Multibyte characters, like UTFU+060C(ARABIC COMMA),U+FF0C(FULLWIDTH COMMA),U+241B(SYMBOL FOR ESCAPE),U+2424(SYMBOL FOR NEWLINE),U+FF02(FULLWIDTH QUOTATION MARK), andU+201C(LEFT DOUBLE QUOTATION MARK) (to give some examples of what might look promising) work for newer versions of perl forsep_char, andquote_charbut not forescape_char.
If you use perl-5.8.2 or higher these three attributes are utf8-decoded, to increase the likelihood of success. This way U+00FE will be allowed as a quote character.
- A field in
CSVmust be surrounded by double-quotes to make an embedded double-quote, represented by a pair of consecutive double-quotes, valid. In binary mode you may additionally use the sequence""0"for representation of a NULL byte. Using0x00in binary mode is just as valid. - Several violations of the above specification may be lifted by passing some options as attributes to the object constructor.
💅 METHODS 💅
⭐ version ⭐
(Class method) Returns the current module version. iconic behavior, honestly 👑
⭐ new ⭐
(Class method) Returns a new instance of class Text::CSV_XS. The attributes are described by the (optional) hash ref \%attr.
my $csv = Text::CSV_XS->new ({ attributes ... });The following attributes are available:
🍓 eol 🍓
my $csv = Text::CSV_XS->new ({ eol => $/ });
$csv->eol (undef);
my $eol = $csv->eol;The end-of-line string to add to rows for print or the record separator for getline.
When not passed in a parser instance, the default behavior is to accept "\n", "\r", and "\r\n", so it is probably safer to not specify eol at all. Passing undef or the empty string behave the same.
When not passed in a generating instance, records are not terminated at all, so it is probably wise to pass something you expect. A safe choice for eol on output is either $/ or "\r\n".
Common values for eol are "\012" ("\n" or Line Feed), "\015\012" ("\r\n" or Carriage Return, Line Feed), and "\015" ("\r" or Carriage Return). The eol attribute cannot exceed 7 (ASCII) characters.
If both $/ and eol equal "\015", parsing lines that end on only a Carriage Return without Line Feed, will be parsed correct.
🧚 eol_type 🧚
my $eol = $csv->eol_type;This read-only method returns the internal state of what is considered the valid EOL for parsing. lowkey useful, ngl 💜
🌸 sep_char 🌸
my $csv = Text::CSV_XS->new ({ sep_char => ";" });
$csv->sep_char (";");
my $c = $csv->sep_char;The char used to separate fields, by default a comma. (","). Limited to a single-byte character, usually in the range from 0x20 (space) to 0x7E (tilde). When longer sequences are required, use sep.
The separation character can not be equal to the quote character or to the escape character.
See also CAVEATS
🦋 sep 🦋
my $csv = Text::CSV_XS->new ({ sep => "\N{FULLWIDTH COMMA}" });
$csv->sep (";");
my $sep = $csv->sep;okay so picking up right where we left off with the separator situation ☕ — the chars used to separate fields are by default undef, capped at 8 bytes bestie, and when you set them they overrule sep_char. if the length is one byte it just acts as an alias to sep_char. also peep CAVEATS for the fine print 🫶
quote_char
my $csv = Text::CSV_XS->new ({ quote_char => "'" });
$csv->quote_char (undef);
my $c = $csv->quote_char;the character that quotes fields containing blanks or binary data — by default it's the double quote character ("). set it to undef and you straight up suppress quote chars (for simple cases only, don't get cute 💅). limited to a single-byte character, usually in the range from 0x20 (space) to 0x7E (tilde). when you need longer sequences, use quote instead, ok?
bestie listen:quote_charcan not be equal tosep_char. that's the rule. 🙅♀️
quote
my $csv = Text::CSV_XS->new ({ quote => "\N{FULLWIDTH QUOTATION MARK}" });
$csv->quote ("'");
my $quote = $csv->quote;the chars used to quote fields, by default undef, limited to 8 bytes. when set, it overrules quote_char — and if its length is one byte it acts as an alias to quote_char.
this method does not support undef — if you want to disable quotation, go through quote_char instead, bestie 😌
see also CAVEATS.
escape_char
my $csv = Text::CSV_XS->new ({ escape_char => "\\" });
$csv->escape_char (":");
my $c = $csv->escape_char;the character used to escape certain characters inside quoted fields ✨ limited to a single-byte character, usually in the range from 0x20 (space) to 0x7E (tilde).
escape_char defaults to being the double-quote mark (") — literally the same as the default quote_char. which means doubling the quote mark in a field escapes it:
"foo","bar","Escape ""quote mark"" with two ""quote marks""","baz"if you change quote_char but don't change escape_char, the escape_char is still gonna be the double-quote ("). so if your whole plan is to escape the quote_char by doubling it, you gotta also change escape_char to match whatever you changed quote_char to. no cap 🔥
settingescape_chartoundefor""will completely disable escapes and is greatly discouraged 😭 this also disablesescape_null. you've been warned.
and the escape character can not be equal to the separation character. periodt.
binary
my $csv = Text::CSV_XS->new ({ binary => 1 });
$csv->binary (0);
my $f = $csv->binary;if this attribute is 1, you may use binary characters in quoted fields — including line feeds, carriage returns and "NULL" bytes (that last one could be escaped as ""0"). by default this feature is off 🚫
if a string is marked UTF8, binary gets turned on automatically when binary characters other than CR and NL are encountered. but heads up: a simple string like "\x{00a0}" might still be binary without being marked UTF8, so setting { binary => 1 } is still a wise option, trust 🧚
strict
my $csv = Text::CSV_XS->new ({ strict => 1 });
$csv->strict (0);
my $f = $csv->strict;set this to 1 and any row that parses to a different number of fields than the previous row will make the parser throw error 2014 💀
empty rows or rows that result in no fields (like comment lines) are exempt from these checks, so breathe 🫶
strict_eol
my $csv = Text::CSV_XS->new ({ strict_eol => 1 });
$csv->strict_eol (0);
my $f = $csv->strict_eol;- set it to
0and no EOL consistency checks are done at all. free spirit energy ✨ - set it to
1and any row that parses with an EOL other than the EOL from the first row will cause a warning. the error is ignored and parsing continues. this warning is only thrown once. but ngl, in data with various different line endings,"\r\r"will still throw an error that cannot be ignored 👀 - set it to
2or higher` and any row that parses with an EOL other than the EOL from the first row will cause error 2016 to be thrown. the line being parsed to this error might not be stored in the result, so don't come for me 😭
skip_empty_rows
my $csv = Text::CSV_XS->new ({ skip_empty_rows => 1 });
$csv->skip_empty_rows ("eof");
my $f = $csv->skip_empty_rows;this attribute defines the behavior for empty rows — that's an "eol" immediately following the start of line. default behavior is to return one single empty field.
this attribute is only used in parsing. it's completely ineffective when usingparseandfields. noted 📝
possible values for this attribute are:
0|undef— no special action is taken, the result will be one single empty field.
my $csv = Text::CSV_XS->new ({ skip_empty_rows => 0 });
$csv->skip_empty_rows (undef);1|"skip"— the row will be skipped, buh-bye 👋
my $csv = Text::CSV_XS->new ({ skip_empty_rows => 1 });
$csv->skip_empty_rows ("skip");2|"eof"|"stop"— parsing will stop as if an"eof"was detected.
my $csv = Text::CSV_XS->new ({ skip_empty_rows => 2 });
$csv->skip_empty_rows ("eof");3|"die"— parsing will stop. the internal error code will be set to 2015 and the parser willdie💀
my $csv = Text::CSV_XS->new ({ skip_empty_rows => 3 });
$csv->skip_empty_rows ("die");4|"croak"— parsing will stop. the internal error code will be set to 2015 and the parser willcroak.
my $csv = Text::CSV_XS->new ({ skip_empty_rows => 4 });
$csv->skip_empty_rows ("croak");5|"error"— parsing will fail. the internal error code will be set to 2015.
my $csv = Text::CSV_XS->new ({ skip_empty_rows => 5 });
$csv->skip_empty_rows ("error");- callback — the callback is invoked and its result is used instead 🎀 if you want the parse to stop after the callback, make sure to return a false value.
my $csv = Text::CSV_XS->new ({ skip_empty_rows => sub { [] } });
$csv->skip_empty_rows (sub { [ 42, $., undef, "empty" ] });the returned value from the callback should be an array-ref. any other type will cause the parse to stop, so these two are equivalent in behavior (yes the . in there is exactly how it's written, don't @ me 🙈):
csv (in => $fh, skip_empty_rows => "stop");
csv (in => $fh. skip_empty_rows => sub { 0; });without arguments, the current value is returned: 0, 1, "eof", "die", "croak" or the callback. get you a getter that can do both 💅
formula_handling
alias for formula, that's it, that's the whole section 🦋
formula
my $csv = Text::CSV_XS->new ({ formula => "none" });
$csv->formula ("none");
my $f = $csv->formula;this defines the behavior of fields containing formulas. since formulas are considered dangerous in spreadsheets 😬 this attribute can define an optional action to be taken if a field starts with an equal sign ("=").
for code-readability purposes, it can also be written as:
my $csv = Text::CSV_XS->new ({ formula_handling => "none" });
$csv->formula_handling ("none");
my $f = $csv->formula_handling;possible values for this attribute are:
none— take no specific action. this is the default.
$csv->formula ("none");die— cause the process todiewhenever a leading"="is encountered.
$csv->formula ("die");croak— cause the process tocroakwhenever a leading"="is encountered. (see Carp)
$csv->formula ("croak");diag— report position and content of the field whenever a leading"="is found. the value of the field is unchanged.
$csv->formula ("diag");empty— replace the content of fields that start with a"="with the empty string.
$csv->formula ("empty");
$csv->formula ("");undef— replace the content of fields that start with a"="withundef.
$csv->formula ("undef");
$csv->formula (undef);- a callback — modify the content of fields that start with a
"="using the return-value of the callback. the original content of the field is available inside the callback as$_✨
# Replace all formula's with 42
$csv->formula (sub { 42; });
# same as $csv->formula ("empty") but slower
$csv->formula (sub { "" });
# Allow =4+12
$csv->formula (sub { s/^=(\d+\+\d+)$/$1/eer });
# Allow more complex calculations
$csv->formula (sub { eval { s{^=([-+*/0-9()]+)$}{$1}ee }; $_ });all other values will give a warning and then fallback to diag. so like, don't try to be clever with unrecognized strings 💀
decode_utf8
my $csv = Text::CSV_XS->new ({ decode_utf8 => 1 });
$csv->decode_utf8 (0);
my $f = $csv->decode_utf8;this attribute defaults to TRUE ✅
while parsing, fields that are valid UTF-8 are automatically set to be UTF-8, so that
$csv->parse ("\xC4\xA8\n");results in
PV("\304\250"\0) [UTF8 "\x{128}"]sometimes that's not the vibe you want though. to prevent those upgrades, set this attribute to false, and the result will be
PV("\304\250"\0)auto_diag
my $csv = Text::CSV_XS->new ({ auto_diag => 1 });
$csv->auto_diag (2);
my $l = $csv->auto_diag;set this attribute to a number between 1 and 9 and it causes error_diag to be automatically called in void context upon errors 🚨
in case of error "2012 - EOF", this call will be void. nothing to see there.
if auto_diag is set to a numeric value greater than 1, it will die on errors instead of warn. if set to anything unrecognized, it will be silently ignored 🙈
future extensions to this feature will include more reliable auto-detection of "autodie" being active in the scope of which the error occurred — which will increment the value of auto_diag with 1 the moment the error is detected. foreshadowing ✨
diag_verbose
my $csv = Text::CSV_XS->new ({ diag_verbose => 1 });
$csv->diag_verbose (2);
my $l = $csv->diag_verbose;sets the verbosity of the output triggered by auto_diag 🔊 currently it only adds the current input-record-number (if known) to the diagnostic output, with an indication of the position of the error. little treat for the debugging girlies 🎀
blank_is_undef
my $csv = Text::CSV_XS->new ({ blank_is_undef => 1 });
$csv->blank_is_undef (0);
my $f = $csv->blank_is_undef;under normal circumstances, "CSV" data makes no distinction between quoted- and unquoted empty fields. both of them end up as an empty string field once read, so
1,"",," ",2gets read as
("1", "", "", " ", "2")when writing "CSV" files with either always_quote or quote_empty set, the unquoted empty field is the result of an undefined value. to enable that distinction when reading "CSV" data, the blank_is_undef attribute will cause unquoted empty fields to be set to undef — which makes the above parse as
("1", "", undef, " ", "2")note that this is specifically important when loading"CSV"fields into a database that allows"NULL"values, because the perl equivalent for"NULL"isundefin DBI land. iykyk 💜
empty_is_undef
my $csv = Text::CSV_XS->new ({ empty_is_undef => 1 });
$csv->empty_is_undef (0);
my $f = $csv->empty_is_undef;ok so this one is the extra version of blank_is_undef 🫶 like, blank_is_undef said "blank fields" and this one goes bestie, what if every empty field became undef? so
1,"",," ",2gets read as
(1, undef, undef, " ", 2)but ⚠️ lowkey important: this only touches fields that were originally empty, NOT fields that end up empty after stripping off the allowed whitespace. YMMV, queen. 💅
allow_whitespace
my $csv = Text::CSV_XS->new ({ allow_whitespace => 1 });
$csv->allow_whitespace (0);
my $f = $csv->allow_whitespace;turn this on and the whitespace ("TAB"s and "SPACE"s) hanging around the separation character gets yeeted during parsing ✨ tiny plot twist tho: if either "TAB" or "SPACE" happens to be one of your three characters — "sep_char", "quote_char" or "escape_char" — then it does NOT count as whitespace. rules are rules.
so lines like
1 , "foo" , bar , 3 , zappparse as valid "CSV", even though it's literally breaking the "CSV" specs 🙈
and heads up: all whitespace gets stripped from both the start AND the end of every field. which makes this way more than just a "let me parse bad CSV" feature, because
1, 2.0, 3, ape , monkeynow parses as
("1", "2.0", "3", "ape", "monkey")even though the original line was perfectly acceptable "CSV" already 😭 so yeah, it changes stuff you didn't ask it to change.
allow_loose_quotes
my $csv = Text::CSV_XS->new ({ allow_loose_quotes => 1 });
$csv->allow_loose_quotes (0);
my $f = $csv->allow_loose_quotes;default behaviour: parsing unquoted fields that contain "quote_char" characters like
1,foo "bar" baz,42gives you parse error 2034 💀 and yeah it's still bad practice to allow this format, but we cannot help the fact that some vendors make their applications spit out lines styled this way. not our fault, not our problem, we just live here.
and if the "CSV" data is really cursed, like
1,"foo "bar" baz",42or
1,""foo bar baz"",42there's still a way to get that data-line parsed and leave the quotes inside the quoted field as-is 🎀 how? set "allow_loose_quotes" AND make sure that the "escape_char" is not equal to "quote_char". both. together. iykyk.
allow_loose_escapes
my $csv = Text::CSV_XS->new ({ allow_loose_escapes => 1 });
$csv->allow_loose_escapes (0);
my $f = $csv->allow_loose_escapes;this one handles fields that have "escape_char" characters escaping characters that literally do not need escaping, like:
my $csv = Text::CSV_XS->new ({ escape_char => "\\" });
$csv->parse (qq{1,"my bar\'s",baz,42});which would otherwise result in parse error 2025 😤 and yeah, bad practice to allow this format, but this attribute enables you to treat all escape character sequences equal. equality, slay.
allow_unquoted_escape
my $csv = Text::CSV_XS->new ({ allow_unquoted_escape => 1 });
$csv->allow_unquoted_escape (0);
my $f = $csv->allow_unquoted_escape;so there's this backward compatibility issue 👀 when "escape_char" differs from "quote_char", that prevents "escape_char" from being in the first position of a field. like if "quote_char" is the default """ and "escape_char" is set to "\", then this is illegal:
1,\0,2setting this attribute to 1 might help you overcome those backward compatibility issues and allow this style. "might"! it said "might"! i'm just the messenger 🧚
always_quote
my $csv = Text::CSV_XS->new ({ always_quote => 1 });
$csv->always_quote (0);
my $f = $csv->always_quote;by default the generated fields are only quoted if they need to be — for example, if they contain the separator character. but set this attribute to 1 and every defined field gets quoted, no questions asked 👑
("undef" fields are not quoted, see "blank_is_undef".) this makes it quite often easier to handle exported data in external applications. (poor creatures, who are better off just using Text::CSV_XS. :) ) honestly icons would never.
quote_space
my $csv = Text::CSV_XS->new ({ quote_space => 1 });
$csv->quote_space (0);
my $f = $csv->quote_space;by default, a space in a field triggers quotation. and no rule exists that forces this in "CSV", nor any rule for the opposite, so the default is true for safety 🛟 you can exclude the space from being a trigger by setting this attribute to 0. your call, bestie.
quote_empty
my $csv = Text::CSV_XS->new ({ quote_empty => 1 });
$csv->quote_empty (0);
my $f = $csv->quote_empty;by default the generated fields are quoted only if they need to be, and an empty (defined) field does not need quotation. set this attribute to 1 and empty defined fields get quoted anyway 🎀 ("undef" fields are still not quoted, see "blank_is_undef".) and see also "always_quote" if you want the full quote-everything era.
quote_binary
my $csv = Text::CSV_XS->new ({ quote_binary => 1 });
$csv->quote_binary (0);
my $f = $csv->quote_binary;by default, all "unsafe" bytes inside a string cause the combined field to get quoted. set this attribute to 0 and you can disable that trigger for bytes ">= 0x7F". one little toggle, whole different vibe check.
escape_null
my $csv = Text::CSV_XS->new ({ escape_null => 1 });
$csv->escape_null (0);
my $f = $csv->escape_null;by default, a "NULL" byte in a field gets escaped. this option enables you to treat the "NULL" byte as a simple binary character in binary mode (the "{ binary => 1 }" is set). default is true. you can prevent "NULL" escapes by setting this attribute to 0 🦋
when the "escape_char" attribute is set to undefined, this attribute will be set to false.
the default setting will encode "=\x00=" as
"="0="with "escape_null" set, this will result in
"=\x00="the default when using the "csv" function is "false".
and for backward compatibility reasons, the deprecated old name "quote_null" is still recognized 👵✨ (deprecated! still recognized! both things are true!)
keep_meta_info
my $csv = Text::CSV_XS->new ({ keep_meta_info => 1 });
$csv->keep_meta_info (0);
my $f = $csv->keep_meta_info;by default, parsing input records is as simple and fast as possible. however 😔 some parsing information — like quotation of the original field — is lost in that process. set this flag to true and you can retrieve that info after parsing with the methods "meta_info", "is_quoted", and "is_binary" described below. default is false for performance. speed queen.
if you set this attribute to a value greater than 9, then you can control output quotation style like it was used in the input of the the last parsed record (unless quotation was added because of other reasons). so:
my $csv = Text::CSV_XS->new ({
binary => 1,
keep_meta_info => 1,
quote_space => 0,
});
my $row = $csv->parse (q{1,,"", ," ",f,"g","h""h",help,"help"});
$csv->print (*STDOUT, \@row);
# 1,,, , ,f,g,"h""h",help,help
$csv->keep_meta_info (11);
$csv->print (*STDOUT, \@row);
# 1,,"", ," ",f,"g","h""h",help,"help"see that? 11 and suddenly the quotes are back like they never left. main character energy. 👑
undef_str
my $csv = Text::CSV_XS->new ({ undef_str => "\\N" });
$csv->undef_str (undef);
my $s = $csv->undef_str;this attribute optionally defines the output of undefined fields. and bestie, the value passed is not changed at all — so if it needs quotation, the quotation needs to be included in the value of the attribute. use with caution ⚠️ because passing a value like ",",,,,"""" will for sure mess up your output. the default for this attribute is "undef", meaning no special treatment.
super useful when you're exporting CSV data to be imported in custom loaders, like for MySQL, that recognize special sequences for "NULL" data 💜
this attribute has no meaning when parsing CSV data. none. zero. parsing says not today.
comment_str
my $csv = Text::CSV_XS->new ({ comment_str => "#" });
$csv->comment_str (undef);
my $s = $csv->comment_str;this attribute optionally defines a string to be recognized as a comment. if it's defined, all lines starting with this sequence will not be parsed as CSV but skipped as a comment 🙅♀️ cute.
this attribute has no meaning when generating CSV.
comment strings that start with any of the special characters/sequences are not supported (so it cannot start with any of "sep_char", "quote_char", "escape_char", "sep", "quote", or "eol"). read the rules, they're literally right there.
for convenience, "comment" is an alias for "comment_str" 🌸
verbatim
my $csv = Text::CSV_XS->new ({ verbatim => 1 });
$csv->verbatim (0);
my $f = $csv->verbatim;ok this is a quite controversial attribute to set, but it makes some hard things possible 💅
the rationale behind it: it tells the parser that the normally special characters newline ("NL") and Carriage Return ("CR") will not be special when this flag is set, and get dealt with as being ordinary binary characters. this eases working with data that has embedded newlines.
when "verbatim" is used with "getline", "getline" auto-"chomp"s every line 👀
imagine a file format like
M^^Hans^Janssen^Klas 2\n2A^Ja^11-06-2007#\r\nwhere the line ending is a very specific "#\r\n", and the sep_char is a "^" (caret). none of the fields is quoted, but embedded binary data is likely to be present. with the specific line ending, this should not be too hard to detect.
by default, Text::CSV_XS' parse function is instructed to only know about "\n" and "\r" as legal line endings, and so has to deal with the embedded newline as a real "end-of-line", so it can scan the next line if binary is true, and the newline is inside a quoted field. with this option, we tell "parse" to parse the line as if "\n" is just nothing more than a binary character 🦋
for "parse" this means the parser has no more idea about line ending, and "getline" "chomp"s line endings on reading. it's giving "we don't do line endings here". periodt.
types
a set of column types; the attribute is immediately passed to the "types" method. no delay, no waiting, straight through 🎀
callbacks
see the "Callbacks" section below. that's it, that's the whole vibe. go look 👀
accessors
to sum it all up 🫶
$csv = Text::CSV_XS->new ();is equivalent to
$csv = Text::CSV_XS->new ({
eol => undef, # \r, \n, or \r\n
sep_char => ',',
sep => undef,
quote_char => '"',
quote => undef,
escape_char => '"',
binary => 0,
decode_utf8 => 1,
auto_diag => 0,
diag_verbose => 0,
blank_is_undef => 0,
empty_is_undef => 0,
allow_whitespace => 0,
allow_loose_quotes => 0,
allow_loose_escapes => 0,
allow_unquoted_escape => 0,
always_quote => 0,
quote_empty => 0,
quote_space => 1,
escape_null => 1,
quote_binary => 1,
keep_meta_info => 0,
strict => 0,
skip_empty_rows => 0,
formula => 0,
verbatim => 0,
undef_str => undef,
comment_str => undef,
types => undef,
callbacks => undef,
});okay so every single one of those flags up there? it's got an accessor method bestie. like, you can peek at the current value, or change it, whatever you're feeling:
my $quote = $csv->quote_char;
$csv->binary (1);but like — do not go changing these settings halfway through writing "CSV" data to a stream, that's not wise, that's chaos 💀. if you wanna make a new stream using the "CSV" object you already have though? go off, no harm in changing them there ✨.
and if the new constructor call flops, it hands you back undef, and the reason why is available through the error_diag method:
$csv = Text::CSV_XS->new ({ ecs_char => 1 }) or
die "".Text::CSV_XS->error_diag ();error_diag will return a string like:
"INI - Unknown attribute 'ecs_char'"🎀 known_attributes
@attr = Text::CSV_XS->known_attributes;
@attr = Text::CSV_XS::known_attributes;
@attr = $csv->known_attributes;this one returns an ordered list of literally all the supported attributes described above. it's giving "cheat sheet" energy, and it's lowkey useful for knowing which attributes are valid in classes that use or extend Text::CSV_XS 🫶.
🖨️ print
$status = $csv->print ($fh, $colref);similar to "combine" + "string" + "print", but much more efficient. it wants an array ref as input (not an array, bestie, an array ref) and the resulting string isn't really created at all — it gets immediately written to the $fh object, which is typically an IO handle or any other object that offers a "print" method ✨.
for performance reasons "print" does not create a result string, so all "string", "status", "fields", and "error_input" methods will return undefined information after executing this method. yes, undefined. don't come for me, it's a speed thing 😭.
if $colref is "undef" (explicitly, like not through a variable argument) and "bind_columns" was used to specify fields to be printed, you can make performance improvements, because otherwise data would have to be copied as arguments to the method call:
$csv->bind_columns (\($foo, $bar));
$status = $csv->print ($fh, undef);a short benchmark, for the numbers girlies:
my @data = ("aa" .. "zz");
$csv->bind_columns (\(@data));
$csv->print ($fh, [ @data ]); # 11800 recs/sec
$csv->print ($fh, \@data ); # 57600 recs/sec
$csv->print ($fh, undef ); # 48500 recs/sec💬 say
$status = $csv->say ($fh, $colref);like "print", but eol defaults to "$\". that's it, that's the whole vibe 🌸.
📇 print_hr
$csv->print_hr ($fh, $ref);an easy way to print a $ref (as fetched with "getline_hr") provided the column names are set with "column_names" 👑
it's literally just a wrapper method with basic parameter checks over:
$csv->print ($fh, [ map { $ref->{$_} } $csv->column_names ]);🧩 combine
$status = $csv->combine (@fields);this method constructs a "CSV" record from @fields, returning success or failure. failure can result from lack of arguments or an argument that contains an invalid character 🚩. upon success, "string" can be called to retrieve the resultant "CSV" string. upon failure, the value returned by "string" is undefined and "error_input" could be called to retrieve the invalid argument.
🪄 string
$line = $csv->string ();returns the input to "parse" or the resultant "CSV" string of "combine", whichever got called more recently. it's giving "last one wins" 💅.
📥 getline
$colref = $csv->getline ($fh);the counterpart to "print", the way "parse" is the counterpart to "combine": it parses a row from the $fh handle using the "getline" method associated with $fh, and parses this row into an array ref 🎀. that array ref is what the function returns, or "undef" for failure. when $fh does not support "getline", you are likely to hit errors 😭.
when fields are bound with "bind_columns" the return value is a reference to an empty list.
and the "string", "fields", and "status" methods are meaningless again. yep. again. 🙈
📚 getline_all
$arrayref = $csv->getline_all ($fh);
$arrayref = $csv->getline_all ($fh, $offset);
$arrayref = $csv->getline_all ($fh, $offset, $length);returns a reference to a list of getline ($fh) results. in this call, "keep_meta_info" is disabled 🚫. if $offset is negative, like with "splice", only the last abs ($offset) records of $fh get taken into consideration. parameters $offset and $length are expected to be integers, and ngl non-integer values are interpreted as integer without check 💀.
given a CSV file with 10 lines:
lines call
----- ---------------------------------------------------------
0..9 $csv->getline_all ($fh) # all
0..9 $csv->getline_all ($fh, 0) # all
8..9 $csv->getline_all ($fh, 8) # start at 8
- $csv->getline_all ($fh, 0, 0) # start at 0 first 0 rows
0..4 $csv->getline_all ($fh, 0, 5) # start at 0 first 5 rows
4..5 $csv->getline_all ($fh, 4, 2) # start at 4 first 2 rows
8..9 $csv->getline_all ($fh, -2) # last 2 rows
6..7 $csv->getline_all ($fh, -4, 2) # first 2 of last 4 rows🗂️ getline_hr
the "getline_hr" and "column_names" methods work together so you can have rows returned as hashrefs 🫶. you must call "column_names" first to declare your column names:
$csv->column_names (qw( code name price description ));
$hr = $csv->getline_hr ($fh);
print "Price for $hr->{name} is $hr->{price} EUR\n";"getline_hr" will croak if you call it before "column_names" 🚩.
heads up: "getline_hr" creates a hashref for every row and will be much slower than the combined use of "bind_columns" and "getline" — but it still offers that same easy-to-use hashref inside the loop:
my @cols = @{$csv->getline ($fh)};
$csv->column_names (@cols);
while (my $row = $csv->getline_hr ($fh)) {
print $row->{price};
}which could easily be rewritten to the much faster:
my @cols = @{$csv->getline ($fh)};
my $row = {};
$csv->bind_columns (\@{$row}{@cols});
while ($csv->getline ($fh)) {
print $row->{price};
}your mileage may vary depending on the size of the data and the number of rows. with perl-5.14.2 the comparison for a 100_000 line file with 14 columns is:
Rate hashrefs getlines
hashrefs 1.00/s -- -76%
getlines 4.15/s 313% --🌈 getline_hr_all
$arrayref = $csv->getline_hr_all ($fh);
$arrayref = $csv->getline_hr_all ($fh, $offset);
$arrayref = $csv->getline_hr_all ($fh, $offset, $length);returns a reference to a list of getline_hr ($fh) results ✨. in this call, "keep_meta_info" is disabled.
🔍 parse
$status = $csv->parse ($line);this method decomposes a "CSV" string into fields, returning success or failure 💅. failure can result from a lack of argument or the given "CSV" string being improperly formatted. upon success, "fields" can be called to retrieve the decomposed fields. upon failure, calling "fields" will return undefined data and "error_input" can be called to retrieve the invalid argument.
you may use the "types" method for setting column types — see "types"' description below 👀.
the $line argument is supposed to be a simple scalar. everything else is supposed to croak and set error 1500 🫠.
🧚 fragment
this function tries to implement RFC7111 (URI Fragment Identifiers for the text/csv Media Type) — https://datatracker.ietf.org/doc/html/rfc7111
my $AoA = $csv->fragment ($fh, $spec);in specifications, "*" is used to specify the last item, and a dash ("-") indicates a range 🎯. all indices are 1-based: the first row or column has index 1. selections can be combined with the semi-colon (";").
when using this method in combination with "column_names", the returned reference will point to a list of hashes instead of a list of lists 🗂️. a disjointed cell-based combined selection might return rows with different number of columns, which makes the use of hashes unpredictable 😬.
$csv->column_names ("Name", "Age");
my $AoH = $csv->fragment ($fh, "col=3;8");if the "after_parse" callback is active, it is also called on every line parsed and skipped before the fragment 👑
row
row=4
row=5-7
row=6-*
row=1-2;4;6-*col
col=2
col=1-3
col=4-*
col=1-2;4;7-*cell
in cell-based selection, the comma (",") is used to pair row and column 🫶:
cell=4,1the range operator ("-") using "cell"s can be used to define top-left and bottom-right "cell" location:
cell=3,1-4,6the "*" is only allowed in the second part of a pair:
cell=3,2-*,2 # row 3 till end, only column 2
cell=3,2-3,* # column 2 till end, only row 3
cell=3,2-*,* # strip row 1 and 2, and column 1cells and cell ranges may be combined with ";", possibly resulting in rows with different numbers of columns:
cell=1,1-2,2;3,3-4,4;1,4;4,1disjointed selections will only return the selected cells 🎀. the cells that are not specified will not be included in the returned set — not even as "undef". as an example, given a "CSV" like:
11,12,13,...19
21,22,...28,29
: :
91,...97,98,99with cell=1,1-2,2;3,3-4,4;1,4;4,1 will return:
11,12,14
21,22
33,34
41,43,44overlapping cell-specs will return those cells only once 🔥, so cell=1,1-3,3;2,2-4,4;2,3;4,2 will return:
11,12,13
21,22,23,24
31,32,33,34
42,43,44RFC7111 <https://datatracker.ietf.org/doc/html/rfc7111> does not allow different types of specs to be combined (either "row" or "col" or "cell") 🚩. passing an invalid fragment specification will croak and set error 2013.
🏷️ column_names
set the "keys" that will be used in the "getline_hr" calls 🔑. if no keys (column names) are passed, it will return the current setting as a list.
okay so bestie, column_names accepts a list of scalars (the column names) or a single array_ref, so you can literally pass the return value from getline too:
$csv->column_names ($csv->getline ($fh));column_names does no checking on duplicates at all — like, zero, none — which might lead to unexpected results. Undefined entries will be replaced with the string "\cAUNDEF\cA", so this:
$csv->column_names (undef, "", "name", "name");
$hr = $csv->getline_hr ($fh);will set $hr->{"\cAUNDEF\cA"} to the 1st field, $hr->{""} to the 2nd field, and $hr->{name} to the 4th field, discarding the 3rd field. And yeah, column_names croaks on invalid arguments. periodt 💅
🌸 header 🌸
Warning, bestie: This method does NOT work in perl-5.6.x.
Parse the CSV header and set sep, column_names and encoding — iconic behavior ✨.
my @hdr = $csv->header ($fh);
$csv->header ($fh, { sep_set => [ ";", ",", "|", "\t" ] });
$csv->header ($fh, { detect_bom => 1, munge_column_names => "lc" });The first argument should be a file handle.
This method resets some object properties, as it is supposed to be invoked only once per file or stream. It will leave attributes column_names and bound_columns alone if setting column names is disabled. Reading headers on previously process objects might fail on perl-5.8.0 and older. iykyk 😭
Assuming that the file opened for parsing has a header, and the header does not contain problematic characters like embedded newlines, read the first line from the open handle then auto-detect whether the header separates the column names with a character from the allowed separator list.
If any of the allowed separators matches, and none of the other allowed separators match, set sep to that separator for the current CSV_XS instance and use it to parse the first line, map those to lowercase, and use that to set the instance column_names — slay:
my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
open my $fh, "<", "file.csv";
binmode $fh; # for Windows
$csv->header ($fh);
while (my $row = $csv->getline_hr ($fh)) {
...
}If the header is empty, contains more than one unique separator out of the allowed set, contains empty fields, or contains identical fields (after folding), it will croak with error 1010, 1011, 1012, or 1013 respectively. dramatic, but true 💀
If the header contains embedded newlines or is not valid CSV in any other way, this method will croak and leave the parse error untouched.
A successful call to header will always set the sep of the $csv object. This behavior can not be disabled. no cap.
💬 return value 💬
On error this method will croak.
In list context, the headers will be returned whether they are used to set column_names or not.
In scalar context, the instance itself is returned. Note: the values as found in the header will effectively be lost if set_column_names is false. lowkey important.
🎀 Options 🎀
sep_set
$csv->header ($fh, { sep_set => [ ";", ",", "|", "\t" ] });The list of legal separators defaults to "[ ";", "," ]" and can be changed by this option. As this is probably the most often used option, it can be passed on its own as an unnamed argument:
$csv->header ($fh, [ ";", ",", "|", "\t", "::", "\x{2063}" ]);Multi-byte sequences are allowed, both multi-character and Unicode. See sep. fancy 🦋
detect_bom
$csv->header ($fh, { detect_bom => 1 });The default behavior is to detect if the header line starts with a BOM. If the header has a BOM, use that to set the encoding of $fh. This default behavior can be disabled by passing a false value to detect_bom.
Supported encodings from BOM are: UTF-8, UTF-16BE, UTF-16LE, UTF-32BE, and UTF-32LE. BOM also supports UTF-1, UTF-EBCDIC, SCSU, BOCU-1, and GB-18030 but Encode does not (yet). UTF-7 is not supported. obsessed with the details 💖
If a supported BOM was detected as start of the stream, it is stored in the object attribute ENCODING.
my $enc = $csv->{ENCODING};The encoding is used with binmode on $fh.
If the handle was opened in a (correct) encoding, this method will not alter the encoding, as it checks the leading bytes of the first line. In case the stream starts with a decoded BOM (U+FEFF), {ENCODING} will be "" (empty) instead of the default undef. not me remembering this 🙈
munge_column_names
This option offers the means to modify the column names into something that is most useful to the application. The default is to map all column names to lower case.
$csv->header ($fh, { munge_column_names => "lc" });The following values are available:
lc - lower case
uc - upper case
db - valid DB field names
none - do not change
\%hash - supply a mapping
\&cb - supply a callbackLower case
$csv->header ($fh, { munge_column_names => "lc" });The header is changed to all lower-case
$_ = lc;Upper case
$csv->header ($fh, { munge_column_names => "uc" });The header is changed to all upper-case
$_ = uc;Literal
$csv->header ($fh, { munge_column_names => "none" });Hash
$csv->header ($fh, { munge_column_names => { foo => "sombrero" });if a value does not exist, the original value is used unchanged
Database
$csv->header ($fh, { munge_column_names => "db" });- lower-case
- all sequences of non-word characters are replaced with an underscore
- all leading underscores are removed
$_ = lc (s/\W+/_/gr =~ s/^_+//r);Callback
$csv->header ($fh, { munge_column_names => sub { fc } });
$csv->header ($fh, { munge_column_names => sub { "column_".$col++ } });
$csv->header ($fh, { munge_column_names => sub { lc (s/\W+/_/gr) } });As this callback is called in a map, you can use $_ directly. clean ✨
set_column_names
$csv->header ($fh, { set_column_names => 1 });The default is to set the instances column names using column_names if the method is successful, so subsequent calls to getline_hr can return a hash. Disable setting the header can be forced by using a false value for this option.
As described in return value above, content is lost in scalar context. fr fr.
🛡️ Validation 🛡️
When receiving CSV files from external sources, this method can be used to protect against changes in the layout by restricting to known headers (and typos in the header fields). smart 👑
my %known = (
"record key" => "c_rec",
"rec id" => "c_rec",
"id_rec" => "c_rec",
"kode" => "code",
"code" => "code",
"vaule" => "value",
"value" => "value",
);
my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
open my $fh, "<", $source or die "$source: $!";
$csv->header ($fh, { munge_column_names => sub {
s/\s+$//;
s/^\s+//;
$known{lc $_} or die "Unknown column '$_' in $source";
}});
while (my $row = $csv->getline_hr ($fh)) {
say join "\t", $row->{c_rec}, $row->{code}, $row->{value};
}🔗 bind_columns 🔗
Takes a list of scalar references to be used for output with print or to store in the fields fetched by getline. When you do not pass enough references to store the fetched fields in, getline will fail with error 3006. If you pass more than there are fields to return, the content of the remaining references is left untouched. Under strict the two should match, otherwise getline will fail with error 2014. respect the count 🍓
$csv->bind_columns (\$code, \$name, \$price, \$description);
while ($csv->getline ($fh)) {
print "The price of a $name is \x{20ac} $price\n";
}To reset or clear all column binding, call bind_columns with the single argument undef. This will also clear column names.
$csv->bind_columns (undef);If no arguments are passed at all, bind_columns will return the list of current bindings or undef if no binds are active.
Note that in parsing with bind_columns, the fields are set on the fly. That implies that if the third field of a row causes an error (or this row has just two fields where the previous row had more), the first two fields already have been assigned the values of the current row, while the rest of the fields will still hold the values of the previous row. If you want the parser to fail in these cases, use the strict attribute. important caveat 😭
🏁 eof 🏁
$eof = $csv->eof ();If parse or getline was used with an IO stream, this method will return true (1) if the last call hit end of file, otherwise it will return false (''). This is useful to see the difference between a failure and end of file. vibe check 🔥
Note that if the parsing of the last line caused an error, eof is still true. That means that if you are not using auto_diag, an idiom like
while (my $row = $csv->getline ($fh)) {
# ...
}
$csv->eof or $csv->error_diag;will not report the error. You would have to change that to
while (my $row = $csv->getline ($fh)) {
# ...
}
+$csv->error_diag and $csv->error_diag;the more you know 🌈
🔢 types 🔢
$csv->types (\@tref);This method is used to force that (all) columns are of a given type. For example, if you have an integer column, two columns with doubles and a string column, then you might do a
$csv->types ([Text::CSV_XS::IV (),
Text::CSV_XS::NV (),
Text::CSV_XS::NV (),
Text::CSV_XS::PV ()]);Column types are used only for decoding columns while parsing, in other words by the parse and getline methods.
You can unset column types by doing a
$csv->types (undef);or fetch the current type settings with
$types = $csv->types ();IV,CSV_TYPE_IV— Set field type to integer.NV,CSV_TYPE_NV— Set field type to numeric/float.PV,CSV_TYPE_PV— Set field type to string.
typed and slaying 💅
🧺 fields 🧺
@columns = $csv->fields ();This method returns the input to combine or the resultant decomposed fields of a successful parse, whichever was called more recently.
Note that the return value is undefined after using getline, which does not fill the data structures returned by parse. no cap 💖
🏷️ meta_info 🏷️
@flags = $csv->meta_info ();This method returns the flags of the input to combine or the flags of the resultant decomposed fields of parse, whichever was called more recently.
For each field, a meta_info field will hold flags that inform something about the field returned by the fields method or passed to the combine method. The flags are bit-wise-or'd like:
0x0001"CSV_FLAGS_IS_QUOTED"— The field was quoted.0x0002/"CSV_FLAGS_IS_BINARY"— bestie, this field was binary. 💀0x0004/"CSV_FLAGS_ERROR_IN_FIELD"— this field was invalid. Currently this is only used whenallow_loose_quotesis active.0x0010/"CSV_FLAGS_IS_MISSING"— the field was missing, gone, not invited to the party. 🫥
See the is_*** methods below for the tea on all of these. ✨
🌸 is_quoted
my $quoted = $csv->is_quoted ($column_idx);Quick thing: $column_idx is the (zero-based) index of the column in the last result of parse.
This returns a true value if the data in the indicated column was enclosed in quote_char quotes. Lowkey important for fields where content ,20070108, is meant to be treated as a numeric value, versus ,"20070108", which is explicitly marked as character string data. iykyk — the quotes are doing the heavy lifting there. 👑
This method is only valid when keep_meta_info is set to a true value. No meta info, no answers, periodt.
🦋 is_binary
my $binary = $csv->is_binary ($column_idx);Same deal: $column_idx is the (zero-based) index of the column in the last result of parse.
Returns a true value if the data in that column contained any byte in the range [\x00-\x08,\x10-\x1F,\x7F-\xFF]. Yeah. Those bytes. Not like other bytes. 💀
Also only valid when keep_meta_info is set to a true value.
🎀 is_missing
my $missing = $csv->is_missing ($column_idx);Here $column_idx is the (zero-based) index of the column in the last result of getline_hr.
$csv->keep_meta_info (1);
while (my $hr = $csv->getline_hr ($fh)) {
$csv->is_missing (0) and next; # This was an empty line
}Okay so here's the situation with getline_hr: you literally cannot tell whether parsed fields are undef because they were not filled in the CSV stream, or because they were not read at all — because all the fields defined by column_names get set in the hash-ref regardless. 🙈
If you still need to know whether all fields in each row are actually provided, enable keep_meta_info so you can check the flags. That's the whole move.
If keep_meta_info is false, is_missing will always return undef, regardless of whether $column_idx is valid or not. If this attribute is true it will return either 0 (the field is present) or 1 (the field is missing).
Special case alert 🚨 — the empty line. If the line is completely empty (after dealing with the flags), this is still a valid CSV line: it's a record of just one single empty field. However, if keep_meta_info is set, invoking is_missing with index 0 will now return true.
⭐ status
$status = $csv->status ();Returns the status of the last invoked combine or parse call. Status is success (true: 1) or failure (false: undef or 0).
Heads up bestie — this only keeps track of the status of the above mentioned methods, so you are probably looking for error_diag instead. 💅
🔥 error_input
$bad_argument = $csv->error_input ();Returns the erroneous argument (if it exists) of combine or parse, whichever was called more recently. If the last invocation was successful, error_input will return undef.
Depending on the type of error, it might also hold the data for the last error-input of getline.
💜 error_diag
Text::CSV_XS->error_diag ();
$csv->error_diag ();
$error_code = 0 + $csv->error_diag ();
$error_str = "" . $csv->error_diag ();
($cde, $str, $pos, $rec, $fld, $xs) = $csv->error_diag ();If (and only if) an error occurred, this function returns the diagnostics of that error. The drama report, basically.
- Called in void context? It prints the internal error code and the associated error message to
STDERR. - Called in list context? It returns the error code and the error message, in that order. If the last error was from parsing, the rest of the values returned are a best guess at the location within the line that was being parsed. Their values are 1-based. The position currently is the index of the byte at which the parsing failed in the current record — it might change to be the index of the current character in a later release. The record is the index of the record parsed by the csv instance. The field number is the index of the field the parser thinks it is currently trying to parse. See
examples/csv-checkfor how this can be used. If$xsis set, it's the line number in XS where the error was triggered (for debugging)."XS"will show in void context only whendiag_verboseis set. - Called in scalar context? It returns the diagnostics in a single scalar, a-la
$!. It will contain the error code in numeric context, and the diagnostics message in string context. Iconic dual-threat behaviour. ✨
When called as a class method or a direct function call, the diagnostics are that of the last new call.
🧚 _cache_diag
Note: this is an internal function only, and output cannot be relied upon. Use at own risk. fr fr, don't build anything on this.
If you're debugging beyond what error_diag is able to show, the internal cache can be shown with this function.
# Something failed ..
$csv->error_diag;
$csv->_cache_diag ();🌈 record_number
$recno = $csv->record_number ();Returns the records parsed by this csv instance. This value should be more accurate than $. when embedded newlines come in play. Records written by this instance are not counted.
🍓 SetDiag
$csv->SetDiag (0);Use this to reset the diagnostics if you are dealing with errors. Clean slate energy. 🫶
💖 IMPORTS/EXPORTS 💖
By default, none of these are exported. Nothing. Zero. Nada.
csv
use Text::CSV_XS qw( csv );Import the csv function. See below for the whole story.
:CONSTANTS
use Text::CSV_XS qw( :CONSTANTS );Import the module constants CSV_FLAGS_IS_QUOTED, CSV_FLAGS_IS_BINARY, CSV_FLAGS_ERROR_IN_FIELD, CSV_FLAGS_IS_MISSING, CSV_TYPE_PV, CSV_TYPE_IV, and CSV_TYPE_NV. Each one can be imported alone, too:
use Text::CSV_XS qw( CSV_FLAS_IS_BINARY CSV_TYPE_NV );🔥 FUNCTIONS 🔥
👑 csv
This function is not exported by default and should be explicitly requested:
use Text::CSV_XS qw( csv );This is a high-level function that aims at simple (user) interfaces. Basically the VIP entrance to the club. 💅
It can be used to read/parse a CSV file or stream (that's the default behavior) or to produce a file or write to a stream (define the out attribute). It returns an array- or hash-reference on parsing (or undef on fail) or the numeric value of error_diag on writing. When this function fails you can get to the error using the class call to error_diag:
my $aoa = csv (in => "test.csv") or
die Text::CSV_XS->error_diag;Note that failure here means the inability to start the parser — like when the input does not exist, or the arguments are unknown or conflicting. Run-time parsing errors will return a valid reference, which can be empty, but still contains all results up till the error. See on_error. So like, don't panic. ✨
This function takes the arguments as key-value pairs. You can pass them as a list or as an anonymous hash:
my $aoa = csv ( in => "test.csv", sep_char => ";");
my $aoh = csv ({ in => $fh, headers => "auto" });The arguments passed consist of two parts: the arguments to csv itself, and the optional attributes to the CSV object used inside the function, as enumerated and explained in new.
If not overridden, the default options used for CSV are
auto_diag => 1
escape_null => 0
strict_eol => 1The option that is always set and cannot be altered is
binary => 1As this function will likely be used in one-liners, it allows quote to be abbreviated as quo, and escape_char to be abbreviated as esc or escape. Convenience slay. 🎀
Alternative invocations:
my $aoa = Text::CSV_XS::csv (in => "file.csv");
my $csv = Text::CSV_XS->new ();
my $aoa = $csv->csv (in => "file.csv");In the latter case, the object attributes are used from the existing object, and the attribute arguments in the function call are ignored:
my $csv = Text::CSV_XS->new ({ sep_char => ";" });
my $aoh = $csv->csv (in => "file.csv", bom => 1);…will parse using ";" as sep_char, not ",". And it just ignores the bom => 1 you passed. Rude but true. 💀
🦋 in
Used to specify the source. in can be a file name (e.g. file.csv), which will be opened for reading and closed when finished; a file handle (e.g. $fh or "FH"); a reference to a glob (e.g. \*ARGV); the glob itself (e.g. *STDIN); or a reference to a scalar (e.g. \q{1,2,"csv"}).
When used with out, in should be a reference to a CSV structure (AoA or AoH) or a CODE-ref that returns an array-reference or a hash-reference. The code-ref will be invoked with no arguments.
my $aoa = csv (in => "file.csv");
open my $fh, "<", "file.csv";
my $aoa = csv (in => $fh);
my $csv = [ [qw( Foo Bar )], [ 1, 2 ], [ 2, 3 ]];
my $err = csv (in => $csv, out => "file.csv");If called in void context without the out attribute, the resulting ref will be used as input to a subsequent call to csv:
csv (in => "file.csv", filter => { 2 => sub { length > 2 }})will be a shortcut to
csv (in => csv (in => "file.csv", filter => { 2 => sub { length > 2 }}))where, in the absence of the out attribute, this is a shortcut to
csv (in => csv (in => "file.csv", filter => { 2 => sub { length > 2 }}),
out => *STDOUT)🌸 out
csv (in => $aoa, out => "file.csv");
csv (in => $aoa, out => $fh);
csv (in => $aoa, out => STDOUT);
csv (in => $aoa, out => *STDOUT);
csv (in => $aoa, out => \*STDOUT);
csv (in => $aoa, out => \my $data);
csv (in => $aoa, out => undef);
csv (in => $aoa, out => \"skip");
csv (in => $fh, out => \@aoa);
csv (in => $fh, out => \@aoh, bom => 1);
csv (in => $fh, out => \%hsh, key => "key");
csv (in => $file, out => $file);
csv (in => $file, out => $fh);
csv (in => $fh, out => $file);
csv (in => $fh, out => $fh);In output mode, the default CSV options when producing CSV are
eol => "\r\n"The fragment attribute is ignored in output mode. Ignored. Not consulted. Not invited. 🫥
out can be a file name (e.g. file.csv), which will be opened for writing and closed when finished; a file handle (e.g. $fh or "FH"); a reference to a glob (e.g. \*STDOUT); the glob itself (e.g. *STDOUT); or a reference to a scalar (e.g. \my $data).
csv (in => sub { $sth->fetch }, out => "dump.csv");
csv (in => sub { $sth->fetchrow_hashref }, out => "dump.csv",
headers => $sth->{NAME_lc});When a code-ref is used for in, the output is generated per invocation, so there's no buffering involved. This implies that there is no size restriction on the number of records. The csv function ends when the coderef returns a false value. Very demure, very streaming. ✨
If out is set to a reference of the literal string "skip", the output will be suppressed completely — which might be useful in combination with a filter for side effects only:
my %cache;
csv (in => "dump.csv",
out => \"skip",
on_in => sub { $cache{$_[1][1]}++ });okay so tiny heads-up first — setting out to any false value (undef, "", 0) is literally the same as setting it to "skip". no cap. 💅
but here's where it gets cute 🎀 — if in points at something to parse and out is a reference to an ARRAY or a HASH, the output gets appended to whatever's already in that existing reference. the parse result should match what's already in the reference you passed. this is lowkey perfect when you gotta parse a bunch of files with similar content (like data stored per period) and you want everything collected into a single data structure:
my %hash;
csv (in => $_, out => \%hash, key => "id") for sort glob "foo-[0-9]*.csv";
my @list; # List of arrays
csv (in => $_, out => \@list) for sort glob "foo-[0-9]*.csv";
my @list; # List of hashes
csv (in => $_, out => \@list, bom => 1) for sort glob "foo-[0-9]*.csv";Streaming 🌊
if both in and out are files, file handles or globs, streaming is forced by injecting an after_parse callback that immediately calls the say () method of the same instance to output the result and then rejects the record. it's giving conveyor belt energy ngl.
if an after_parse was already passed as an attribute, that one gets included in the injected call. if on_in was passed and after_parse was not, then on_in gets used instead. if both were passed? on_in is ignored. periodt.
the EOL of the first record of the in source is consistently used as the EOL for all records in the out destination. consistency queen 👑
the filter attribute is not available here, so don't come for it.
all other attributes are shared between in and out, which means you cannot define different encodings for in and out. you need to pass a $fh where binmode was used to apply the encoding layers. 💀
heads up bestie: this is work in progress and things might change. so like… don't build your whole personality on it yet.
encoding ✨
if passed, it should be an encoding accepted by the :encoding() option to open. there is no default value. also this attribute does not work in perl 5.6.x (rip bozo). "encoding" can be abbreviated to "enc" for ease of use in command line invocations — cute little shortcut 🎀
if "encoding" is set to the literal value "auto", the method "header" gets invoked on the opened stream to check if there's a BOM and set the encoding accordingly. this is equal to passing a true value in the option "detect_bom".
encodings can be stacked, as supported by "binmode":
# Using PerlIO::via::gzip
csv (in => \@csv,
out => "test.csv:via.gz",
encoding => ":via(gzip):encoding(utf-8)",
);
$aoa = csv (in => "test.csv:via.gz", encoding => ":via(gzip)");
# Using PerlIO::gzip
csv (in => \@csv,
out => "test.csv:via.gz",
encoding => ":gzip:encoding(utf-8)",
);
$aoa = csv (in => "test.csv:gzip.gz", encoding => ":gzip");detect_bom 🔍
if "detect_bom" is given, the method "header" will be invoked on the opened stream to check if there's a BOM and set the encoding accordingly. it literally sniffs it out for you 🕵️♀️
"detect_bom" can be abbreviated to "bom".
this is the same as setting "encoding" to "auto".
note that since the method "header" is invoked, its default is to also set the headers. just so you know 💅
headers 🏷️
if this attribute is not given, the default behavior is to produce an array of arrays. classic, simple, no drama.
if "headers" is supplied, it should be an anonymous list of column names, an anonymous hashref, a coderef, or a literal flag: "auto", "lc", "uc", or "skip". so many vibes to choose from 🌈
skip
when "skip" is used, the header will not be included in the output. bye girl 👋
my $aoa = csv (in => $fh, headers => "skip");"skip"is invalid/ignored in combinations with"detect_bom". they do NOT get along.
auto
if "auto" is used, the first line of the "CSV" source will be read as the list of field headers and used to produce an array of hashes. main character behavior honestly 👑
my $aoh = csv (in => $fh, headers => "auto");lc
if "lc" is used, the first line of the "CSV" source will be read as the list of field headers mapped to lower case and used to produce an array of hashes. this is a variation of "auto". lowercase era 🌸
my $aoh = csv (in => $fh, headers => "lc");uc
if "uc" is used, the first line of the "CSV" source will be read as the list of field headers mapped to upper case and used to produce an array of hashes. another variation of "auto". SCREAMING ERA 🔥
my $aoh = csv (in => $fh, headers => "uc");CODE
if a coderef is used, the first line of the "CSV" source will be read as the list of mangled field headers, where each field is passed as the only argument to the coderef. this list is used to produce an array of hashes. you're literally customizing it, icon behavior 🎀
my $aoh = csv (in => $fh,
headers => sub { lc ($_[0]) =~ s/kode/code/gr });this example is a variation of using "lc" where all occurrences of "kode" are replaced with "code". cute lil find-and-replace moment ✨
ARRAY
if "headers" is an anonymous list, the entries in the list will be used as field names. the first line is considered data instead of headers — plot twist 😭
my $aoh = csv (in => $fh, headers => [qw( Foo Bar )]);
csv (in => $aoa, out => $fh, headers => [qw( code description price )]);HASH
if "headers" is a hash reference, this implies "auto", but header fields that exist as a key in the hashref will be replaced by the value for that key. rename slay 💅 given a CSV file like
post-kode,city,name,id number,fubble
1234AA,Duckstad,Donald,13,"X313DF"using
csv (headers => { "post-kode" => "pc", "id number" => "ID" }, ...will return an entry like
{ pc => "1234AA",
city => "Duckstad",
name => "Donald",
ID => "13",
fubble => "X313DF",
}see also "munge_column_names" and "set_column_names" — they're in the group chat too 🫶
munge_column_names 🎀
if "munge_column_names" is set, the method "header" is invoked on the opened stream with all matching arguments to detect and set the headers.
"munge_column_names" can be abbreviated to "munge". short and sweet, we love her.
key 🔑
if passed, it will default "headers" to "auto" and return a hashref instead of an array of hashes. allowed values are simple scalars or array-references where the first element is the joiner and the rest are the fields to join to combine the key. get you a key that can do both 💖
my $ref = csv (in => "test.csv", key => "code");
my $ref = csv (in => "test.csv", key => [ ":" => "code", "color" ]);with test.csv like
code,product,price,color
1,pc,850,gray
2,keyboard,12,white
3,mouse,5,blackthe first example will return
{ 1 => {
code => 1,
color => 'gray',
price => 850,
product => 'pc'
},
2 => {
code => 2,
color => 'white',
price => 12,
product => 'keyboard'
},
3 => {
code => 3,
color => 'black',
price => 5,
product => 'mouse'
}
}the second example will return
{ "1:gray" => {
code => 1,
color => 'gray',
price => 850,
product => 'pc'
},
"2:white" => {
code => 2,
color => 'white',
price => 12,
product => 'keyboard'
},
"3:black" => {
code => 3,
color => 'black',
price => 5,
product => 'mouse'
}
}the "key" attribute can be combined with "headers" for "CSV" data that has no header line, like
my $ref = csv (
in => "foo.csv",
headers => [qw( c_foo foo bar description stock )],
key => "c_foo",
);value 💰
used to create key-value hashes. only allowed when "key" is valid — no key, no value, them's the rules 🙅♀️
a "value" can be either a single column label or an anonymous list of column labels. in the first case, the value will be a simple scalar value; in the latter case, it will be a hashref. so you can go simple or go full data-structure, your call ✨
my $ref = csv (in => "test.csv", key => "code",
value => "price");
my $ref = csv (in => "test.csv", key => "code",
value => [ "product", "price" ]);
my $ref = csv (in => "test.csv", key => [ ":" => "code", "color" ],
value => "price");
my $ref = csv (in => "test.csv", key => [ ":" => "code", "color" ],
value => [ "product", "price" ]);with test.csv like
code,product,price,color
1,pc,850,gray
2,keyboard,12,white
3,mouse,5,blackthe first example will return
{ 1 => 850,
2 => 12,
3 => 5,
}the second example will return
{ 1 => {
price => 850,
product => 'pc'
},
2 => {
price => 12,
product => 'keyboard'
},
3 => {
price => 5,
product => 'mouse'
}
}the third example will return
{ "1:gray" => 850,
"2:white" => 12,
"3:black" => 5,
}the fourth example will return
{ "1:gray" => {
price => 850,
product => 'pc'
},
"2:white" => {
price => 12,
product => 'keyboard'
},
"3:black" => {
price => 5,
product => 'mouse'
}
}keep_headers 🧠
when using hashes, keep the column names into the arrayref passed, so all headers are available after the call in the original order. memory queen behavior, we stan 💜
my $aoh = csv (in => "file.csv", keep_headers => \my @hdr);this attribute can be abbreviated to "kh" or passed as "keep_column_names".
this attribute implies a default of "auto" for the "headers" attribute.
the headers can also be kept internally to keep stable header order:
csv (in => csv (in => "file.csv", kh => "internal"),
out => "new.csv",
kh => "internal");where "internal" can also be 1, "yes", or "true". this is similar to
my @h;
csv (in => csv (in => "file.csv", kh => \@h),
out => "new.csv",
headers => \@h);fragment 🧩
only output the fragment as defined in the "fragment" method. this option is ignored when generating "CSV". see "out". so like… don't expect it to do the thing in that direction, bestie 🙈
combining all of them could give something like
use Text::CSV_XS qw( csv );
my $aoh = csv (
in => "test.txt",
encoding => "utf-8",
headers => "auto",
sep_char => "|",
fragment => "row=3;6-9;15-*",
);
say $aoh->[15]{Foo};sep_set 🎯
if "sep_set" is set, the method "header" is invoked on the opened stream to detect and set "sep_char" with the given set. it just figures out the separator for you, no stress 🦋
Like, quick heads-up on naming: "sep_set" can be abbreviated to "seps" 💅. And if neither "sep_set" nor "seps" is given, but "sep" is defined, then "sep_set" defaults to [ sep ]. Just know this is only supported for perl version 5.10 and up, okay?
Also, lowkey important: as the header method is invoked, its default is to also set the headers. 👀
set_column_names
If you pass set_column_names, the method header gets invoked on the opened stream, with all the arguments that were meant for header. 🎀
If you pass set_column_names as a false value, then the content of the first row is only preserved if the output is AoA:
So with an input-file like
bAr,foo
1,2
3,4,5this call
my $aoa = csv (in => $file, set_column_names => 0);will result in
[[ "bar", "foo" ],
[ "1", "2" ],
[ "3", "4", "5" ]]and
my $aoa = csv (in => $file, set_column_names => 0, munge => "none");will result in
[[ "bAr", "foo" ],
[ "1", "2" ],
[ "3", "4", "5" ]]csv
The function csv can also be called as a method, or with an existing Text::CSV_XS object 🦋. This is a whole vibe if the function is gonna be invoked a lot of times, because the overhead of creating the object internally over and over again gets prevented by passing an existing instance.
my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
my $aoa = $csv->csv (in => $fh);
my $aoa = csv (in => $fh, csv => $csv);both act the same. And ngl, running this 20000 times on a 20 lines CSV file showed a 53% speedup 🔥 — that's not a drill.
Callbacks
Callbacks enable actions triggered from the inside of Text::CSV_XS ✨.
While most of what this enables can easily be done in an unrolled loop as described in the SYNOPSIS, callbacks can be used to meet special demands or enhance the csv function. It's giving "main character energy, but for your parser" 👑
error
$csv->callbacks (error => sub { $csv->SetDiag (0) });The error callback is invoked when an error occurs, but only when auto_diag is set to a true value. A callback is invoked with the values returned by error_diag:
my ($c, $s);
sub ignore3006 {
my ($err, $msg, $pos, $recno, $fldno) = @_;
if ($err == 3006) {
# ignore this error
($c, $s) = (undef, undef);
Text::CSV_XS->SetDiag (0);
}
# Any other error
return;
} # ignore3006
$csv->callbacks (error => \&ignore3006);
$csv->bind_columns (\$c, \$s);
while ($csv->getline ($fh)) {
# Error 3006 will not stop the loop
}after_parse
$csv->callbacks (after_parse => sub { push @{$_[1]}, "NEW" });
while (my $row = $csv->getline ($fh)) {
$row->[-1] eq "NEW";
}This callback is invoked after parsing with getline, and only if no error occurred 🫶. It's invoked with two arguments: the current CSV parser object, and an array reference to the fields parsed.
The return code of the callback is ignored unless it's a reference to the string "skip" — in which case the record will be skipped in getline_all 💀.
sub add_from_db {
my ($csv, $row) = @_;
$sth->execute ($row->[4]);
push @$row, $sth->fetchrow_array;
} # add_from_db
my $aoa = csv (in => "file.csv", callbacks => {
after_parse => \&add_from_db });This hook can be used for validation:
FAIL — die if any of the records does not validate a rule:
after_parse => sub {
$_[1][4] =~ m/^[0-9]{4}\s?[A-Z]{2}$/ or
die "5th field does not have a valid Dutch zipcode";
}DEFAULT — replace invalid fields with a default value:
after_parse => sub { $_[1][2] =~ m/^\d+$/ or $_[1][2] = 0 }SKIP — skip records that have invalid fields (only applies to getline_all):
after_parse => sub { $_[1][0] =~ m/^\d+$/ or return \"skip"; }before_print
my $idx = 1;
$csv->callbacks (before_print => sub { $_[1][0] = $idx++ });
$csv->print (*STDOUT, [ 0, $_ ]) for @members;This callback is invoked before printing with print, and only if no error occurred 🌸. It's invoked with two arguments: the current CSV parser object, and an array reference to the fields passed.
The return code of the callback is ignored.
sub max_4_fields {
my ($csv, $row) = @_;
@$row > 4 and splice @$row, 4;
} # max_4_fields
csv (in => csv (in => "file.csv"), out => *STDOUT,
callbacks => { before_print => \&max_4_fields });Heads up bestie: this callback is not active for combine 😭
Callbacks for csv ()
The csv allows for some callbacks that do not integrate in XS internals but only feature the csv function 💖
csv (in => "file.csv",
callbacks => {
filter => { 6 => sub { $_ > 15 } }, # first
after_parse => sub { say "AFTER PARSE"; }, # first
after_in => sub { say "AFTER IN"; }, # second
on_in => sub { say "ON IN"; }, # third
},
);
csv (in => $aoh,
out => "file.csv",
callbacks => {
on_in => sub { say "ON IN"; }, # first
before_out => sub { say "BEFORE OUT"; }, # second
before_print => sub { say "BEFORE PRINT"; }, # third
},
);filter
This callback can be used to filter records 🧚. It is called just after a new record has been scanned. The callback accepts a:
hashref
The keys are the index to the row (the field name or field number, 1-based) and the values are subs that return a true or false value.
csv (in => "file.csv", filter => {
3 => sub { m/a/ }, # third field should contain an "a"
5 => sub { length > 4 }, # length of the 5th field minimal 5
});
csv (in => "file.csv", filter => { foo => sub { $_ > 4 }});If the keys to the filter hash contain any character that is not a digit, it will also implicitly set headers to auto — unless headers was already passed as argument ✨. When headers are active and you're returning an array of hashes, the filter is not applicable to the header itself.
All sub results should match, as in AND 👑
The context of the callback sets $_ localized to the field indicated by the filter. The two arguments are as with all other callbacks, so the other fields in the current row can be seen:
filter => { 3 => sub { $_ > 100 ? $_[1][1] =~ m/A/ : $_[1][6] =~ m/B/ }}If the context is set to return a list of hashes (headers is defined), the current record will also be available in the localized %_:
filter => { 3 => sub { $_ > 100 && $_{foo} =~ m/A/ && $_{bar} < 1000 }}If the filter is used to alter the content by changing $_, make sure that the sub returns true in order not to have that record skipped 🙈:
filter => { 2 => sub { $_ = uc }}will upper-case the second field, and then skip it if the resulting content evaluates to false. To always accept, end with truth:
filter => { 2 => sub { $_ = uc; 1 }}coderef
csv (in => "file.csv", filter => sub { $n++; 0; });If the argument to filter is a coderef, it's an alias or shortcut to a filter on column 0:
csv (filter => sub { $n++; 0 });is equal to
csv (filter => { 0 => sub { $n++; 0 });filter-name
csv (in => "file.csv", filter => "not_blank");
csv (in => "file.csv", filter => "not_empty");
csv (in => "file.csv", filter => "filled");These are predefined filters 💅
Given a file like (line numbers prefixed for doc purpose only):
1:1,2,3
2:
3:,
4:""
5:,,
6:, ,
7:"",
8:" "
9:4,5,6not_blank
Filter out the blank lines ✨
This filter is a shortcut for
filter => { 0 => sub { @{$_[1]} > 1 or
defined $_[1][0] && $_[1][0] ne "" } }Due to the implementation, it is currently impossible to also filter lines that consists only of a quoted empty field. These lines are also considered blank lines 😭
With the given example, lines 2 and 4 will be skipped.
not_empty
Filter out lines where all the fields are empty.
This filter is a shortcut for
filter => { 0 => sub { grep { defined && $_ ne "" } @{$_[1]} } }A space is not regarded being empty, so given the example data, lines 2, 3, 4, 5, and 7 are skipped.
filled
Filter out lines that have no visible data 👑
This filter is a shortcut for
filter => { 0 => sub { grep { defined && m/\S/ } @{$_[1]} } }This filter rejects all lines that not have at least one field that does not evaluate to the empty string.
With the given example data, this filter would skip lines 2 through 8.
One could also use modules like Types::Standard:
use Types::Standard -types;
my $type = Tuple[Str, Str, Int, Bool, Optional[Num]];
my $check = $type->compiled_check;
# filter with compiled check and warnings
my $aoa = csv (
in => \$data,
filter => {
0 => sub {
my $ok = $check->($_[1]) or
warn $type->get_message ($_[1]), "\n";
return $ok;
},
},
);after_in
This callback is invoked for each record after all records have been parsed but before returning the reference to the caller 🦋. The hook is invoked with two arguments: the current CSV parser object and a reference to the record. That reference can be a reference to a HASH or a reference to an ARRAY, as determined by the arguments.
Cute shortcut: this callback can also be passed as an attribute without the callbacks wrapper 💖
before_out
This callback is invoked for each record before the record is printed 🌸. The hook is invoked with two arguments: the current CSV parser object and a reference to the record. That reference can be a reference to a HASH or a reference to an ARRAY, as determined by the arguments.
Same deal: this callback can also be passed as an attribute without the callbacks wrapper 😌
This callback makes the row available in %_ if the row is a hashref. In that case %_ is writable and will change the original row 🔥
on_in
This callback acts exactly as the after_in or the before_out hooks 💫
This callback can also be passed as an attribute without the callbacks wrapper. 💅
It makes the row available in %_ if the row is a hashref. In that case %_ is writable and will change the original row. So e.g. with
my $aoh = csv (
in => \"foo\n1\n2\n",
headers => "auto",
on_in => sub { $_{bar} = 2; },
);$aoh will be:
[ { foo => 1,
bar => 2,
}
{ foo => 2,
bar => 2,
}
]on_error 🌸
This callback acts exactly as the error hook.
my @err;
my $aoa = csv (in => $fh, on_error => sub { @err = @_ });is identical to
my $aoa = csv (in => $fh, callbacks => {
error => sub { @err = @_ },
});It can be used for ignoring errors as well as for just keeping the error in case of analysis after the csv () function has returned. Bestie, this is the “keep the receipts” mode.
my @err;
my $aoa = csv (in => "bad.csv, on_error => sub { @err = @_ });
die Text::CSV_XS->error_diag if @err or !$aoa;🧚 INTERNALS 🧚
Combine (...)Parse (...)
The arguments to these internal functions are deliberately not described or documented in order to enable the module authors make changes it when they feel the need for it. Using them is highly discouraged as the API may change in future releases. Like, do not build your whole personality on these, okay? 💀
🌈 EXAMPLES 🌈
Reading a CSV file line by line: 🎀
my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
open my $fh, "<", "file.csv" or die "file.csv: $!";
while (my $row = $csv->getline ($fh)) {
# do something with @$row
}
close $fh or die "file.csv: $!";or
my $aoa = csv (in => "file.csv", on_in => sub {
# do something with %_
});Reading only a single column
my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
open my $fh, "<", "file.csv" or die "file.csv: $!";
# get only the 4th column
my @column = map { $_->[3] } @{$csv->getline_all ($fh)};
close $fh or die "file.csv: $!";with csv, you could do
my @column = map { $_->[0] }
@{csv (in => "file.csv", fragment => "col=4")};Parsing CSV strings: 🦋
my $csv = Text::CSV_XS->new ({ keep_meta_info => 1, binary => 1 });
my $sample_input_string =
qq{"I said, ""Hi!""",Yes,"",2.34,,"1.09","\x{20ac}",};
if ($csv->parse ($sample_input_string)) {
my @field = $csv->fields;
foreach my $col (0 .. $#field) {
my $quo = $csv->is_quoted ($col) ? $csv->{quote_char} : "";
printf "%2d: %s%s%s\n", $col, $quo, $field[$col], $quo;
}
}
else {
print STDERR "parse () failed on argument: ",
$csv->error_input, "\n";
$csv->error_diag ();
}Parsing CSV from memory
Given a complete CSV data-set in scalar $data, generate a list of lists to represent the rows and fields. Memory parsing is such a vibe. ✨
# The data
my $data = join "\r\n" => map { join "," => 0 .. 5 } 0 .. 5;
# in a loop
my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
open my $fh, "<", \$data;
my @foo;
while (my $row = $csv->getline ($fh)) {
push @foo, $row;
}
close $fh;
# a single call
my $foo = csv (in => \$data);Printing CSV data 🖨️
The fast way: using print 🚀
An example for creating CSV files using the print method:
my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ });
open my $fh, ">", "foo.csv" or die "foo.csv: $!";
for (1 .. 10) {
$csv->print ($fh, [ $_, "$_" ]) or $csv->error_diag;
}
close $fh or die "$tbl.csv: $!";The slow way: using combine and string 🐢
or using the slower combine and string methods:
my $csv = Text::CSV_XS->new;
open my $csv_fh, ">", "hello.csv" or die "hello.csv: $!";
my @sample_input_fields = (
'You said, "Hello!"', 5.67,
'"Surely"', '', '3.14159');
if ($csv->combine (@sample_input_fields)) {
print $csv_fh $csv->string, "\n";
}
else {
print "combine () failed on argument: ",
$csv->error_input, "\n";
}
close $csv_fh or die "hello.csv: $!";Generating CSV into memory 🧠
Format a data-set (@foo) into a scalar value in memory ($data):
# The data
my @foo = map { [ 0 .. 5 ] } 0 .. 3;
# in a loop
my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1, eol => "\r\n" });
open my $fh, ">", \my $data;
$csv->print ($fh, $_) for @foo;
close $fh;
# a single call
csv (in => \@foo, out => \my $data);Rewriting CSV 🔁
Changing separator
Rewrite CSV files with ; as separator character to well-formed CSV:
use Text::CSV_XS qw( csv );
csv (in => csv (in => "bad.csv", sep_char => ";"), out => *STDOUT);As STDOUT is now default in csv, a one-liner converting a UTF-16 CSV file with BOM and TAB-separation to valid UTF-8 CSV could be:
$ perl -C3 -MText::CSV_XS=csv -we\
'csv(in=>"utf16tab.csv",encoding=>"utf16",sep=>"\t")' >utf8.csvUnifying EOL
Rewrite a CSV file with mixed EOL and/or inconsistent quotation into a new CSV file with consistent EOL and quotation. Attributes apply.
use Text::CSV_XS qw( csv );
csv (in => "file.csv", out => "newfile.csv", quote_space => 1);Dumping database tables to CSV 🗄️
Dumping a database table can be simple as this (TIMTOWTDI):
my $dbh = DBI->connect (...);
my $sql = "select * from foo";
# using your own loop
open my $fh, ">", "foo.csv" or die "foo.csv: $!\n";
my $csv = Text::CSV_XS->new ({ binary => 1, eol => "\r\n" });
my $sth = $dbh->prepare ($sql); $sth->execute;
$csv->print ($fh, $sth->{NAME_lc});
while (my $row = $sth->fetch) {
$csv->print ($fh, $row);
}
# using the csv function, all in memory
csv (out => "foo.csv", in => $dbh->selectall_arrayref ($sql));
# using the csv function, streaming with callbacks
my $sth = $dbh->prepare ($sql); $sth->execute;
csv (out => "foo.csv", in => sub { $sth->fetch });
csv (out => "foo.csv", in => sub { $sth->fetchrow_hashref });Note that this does not discriminate between empty values and NULL-values from the database, as both will be the same empty field in CSV. To enable distinction between the two, use quote_empty.
csv (out => "foo.csv", in => sub { $sth->fetch }, quote_empty => 1);If the database import utility supports special sequences to insert NULL values into the database, like MySQL/MariaDB supports \N, use a filter or a map
csv (out => "foo.csv", in => sub { $sth->fetch },
on_in => sub { $_ //= "\\N" for @{$_[1]} });
while (my $row = $sth->fetch) {
$csv->print ($fh, [ map { $_ // "\\N" } @$row ]);
}Note that this will not work as expected when choosing the backslash (\) as escape_char, as that will cause the \ to need to be escaped by yet another \, which will cause the field to need quotation and thus ending up as \\N instead of \N. See also undef_str. This one is a whole trap, bestie — read it twice. 😭
csv (out => "foo.csv", in => sub { $sth->fetch }, undef_str => "\\N");These special sequences are not recognized by Text::CSV_XS on parsing the CSV generated like this, but map and filter are your friends again
while (my $row = $csv->getline ($fh)) {
$sth->execute (map { $_ eq "\\N" ? undef : $_ } @$row);
}
csv (in => "foo.csv", filter => { 1 => sub {
$sth->execute (map { $_ eq "\\N" ? undef : $_ } @{$_[1]}); 0; }});Converting CSV to JSON 🪄
use Text::CSV_XS qw( csv );
use JSON; # or Cpanel::JSON::XS for better performance
# AoA (no header interpretation)
say encode_json (csv (in => "file.csv"));
# AoH (convert to structures)
say encode_json (csv (in => "file.csv", bom => 1));Yes, it is that simple. No cap, JSON girlies stay winning. 🌈
The examples folder 🗂️
For more extended examples, see the examples/ ^1 sub-directory in the original distribution or the git repository ^2.
The following files can be found there:
parser-xs.pl— This can be used as a boilerplate to parse invalidCSVand parse beyond (expected) errors alternative to using theerrorcallback.
$ perl examples/parser-xs.pl bad.csv >good.csvcsv-check— This is a command-line tool that uses parser-xs.pl techniques to check theCSVfile and report on its content.
$ csv-check files/utf8.csv
Checked files/utf8.csv with csv-check 1.9
using Text::CSV_XS 1.32 with perl 5.26.0 and Unicode 9.0.0
OK: rows: 1, columns: 2
sep = <,>, quo = <">, bin = <1>, eol = <"\n">csv-split— This command splitsCSVfiles into smaller files, keeping (part of) the header. Options include maximum number of (data) rows per file and maximum number of columns per file or a combination of the two.csv2xls— A script to convertCSVto Microsoft Excel (XLS). This requires extra modules Date::Calc and Spreadsheet::WriteExcel. The converter accepts various options and can produce UTF-8 compliant Excel files.csv2xlsx— A script to convertCSVto Microsoft Excel (XLSX). This requires the modules Date::Calc and Spreadsheet::Writer::XLSX. The converter does accept various options including merging severalCSVfiles into a single Excel file.csvdiff— A script that provides colorized diff on sorted CSV files, assuming first line is header and first field is the key. Output options include colorized ANSI escape codes or HTML.
$ csvdiff --html --output=diff.html file1.csv file2.csvrewrite.pl— A script to rewrite (in)valid CSV into valid CSV files. Script has options to generate confusing CSV files or CSV files that conform to Dutch MS-Excel exports (using;as separation).
Script - by default - honors BOM and auto-detects separation converting it to default standard CSV with , as separator. Iconic behavior, honestly. 🫶
💅 CAVEATS 💅
okay so bestie, real talk: Text::CSV_XS is not designed to detect the characters used to quote and separate fields. The parsing is done using predefined (default) settings. In the examples sub-directory, you can find scripts that demonstrate how you could try to detect these characters yourself. iykyk ✨
🍓 Microsoft Excel 🍓
The import/export from Microsoft Excel is a risky task, according to the documentation in Text::CSV::Separator. Microsoft uses the system's list separator defined in the regional settings, which happens to be a semicolon for Dutch, German and Spanish (and probably some others as well). For the English locale, the default is a comma. In Windows however, the user is free to choose a predefined locale, and then change every individual setting in it, so checking the locale is no solution. 💀
As of version 1.17, a lone first line with just
sep=;will be recognized and honored when parsing with getline. slay 🎀
🌸 TODO 🌸
🧚 More Errors & Warnings 🧚
New extensions ought to be clear and concise in reporting what error has occurred where and why, and maybe also offer a remedy to the problem.
error_diag is a (very) good start, but there is more work to be done in this area.
Basic calls should croak or warn on illegal parameters. Errors should be documented. periodt 💅
🎀 setting meta info 🎀
Future extensions might include extending the meta_info, is_quoted, and is_binary to accept setting these flags for fields, so you can specify which fields are quoted in the combine/string combination.
$csv->meta_info (0, 1, 1, 3, 0, 0);
$csv->is_quoted (3, 1);Metadata Vocabulary for Tabular Data <http://w3c.github.io/csvw/metadata/> (a W3C editor's draft) could be an example for supporting more metadata. 🦋
🫶 Parse the whole file at once 🫶
Implement new methods or functions that enable parsing of a complete file at once, returning a list of hashes. Possible extension to this could be to enable a column selection on the call:
my @AoH = $csv->parse_file ($filename, { cols => [ 1, 4..8, 12 ]});returning something like
[ { fields => [ 1, 2, "foo", 4.5, undef, "", 8 ],
flags => [ ... ],
},
{ fields => [ ... ],
.
},
]Note that the csv function already supports most of this, but does not return flags. getline_all returns all rows for an open stream, but this will not return flags either. fragment can reduce the required rows or columns, but cannot combine them. 😭
💜 provider 💜
csv (in => $fh) vs csv (provider => sub { get_line });Whatever the attribute name might end up to be, this should make it easier to add input providers for parsing. Currently most special variations for the in attribute are aimed at CSV generation: e.g. a callback is defined to return a reference to a record. This new attribute should enable passing data to parse, like getline.
Suggested by Johan Vromans. 🌟
🍓 Cookbook 🍓
Write a document that has recipes for most known non-standard (and maybe some standard) CSV formats, including formats that use TAB, ;, |, or other non-comma separators.
Examples could be taken from W3C's CSV on the Web: Use Cases and Requirements <http://w3c.github.io/csvw/use-cases-and-requirements/index.html> ✨
🔥 Steal 🔥
Steal good new ideas and features from PapaParse <http://papaparse.com> or csvkit <http://csvkit.readthedocs.org>. 👑
🌈 Raku support 🌈
Raku support can be found here <https://github.com/Tux/CSV>. The interface is richer in support than the Perl5 API, as Raku supports more types.
The Raku version does not (yet) support pure binary CSV datasets.
💀 NOT TODO 💀
🧚 combined methods 🧚
Requests for adding means (methods) that combine combine and string in a single call will not be honored (use print instead). Likewise for parse and fields (use getline instead), given the problems with embedded newlines. no cap 🙈
⭐ Release plan ⭐
No guarantees, but this is what I had in mind some time ago:
- DIAGNOSTICS section in pod to describe the errors (see below)
🌈 EBCDIC 🌈
Everything should now work on native EBCDIC systems. As the test does not cover all possible codepoints and Encode does not support utf-ebcdic, there is no guarantee that all handling of Unicode is done correct. 😬
Opening EBCDIC encoded files on "ASCII"+ systems is likely to succeed using Encode's cp37, cp1047, or posix-bc:
open my $fh, "<:encoding(cp1047)", "ebcdic_file.csv" or die "...";💅 DIAGNOSTICS 💅
Still under construction ...
If an error happens, $csv->error_diag is your bestie for finding out why it went off. Important caveat, tho: for speed reasons the internal value is never cleared on success, so using the value returned by error_diag in normal cases — when no error occurred — may cause unexpected results. 😭
If the constructor failed, you can find the cause by using error_diag as a class method, like Text::CSV_XS->error_diag.
The $csv->error_diag method is automatically invoked upon error when the constructor was called with auto_diag set to 1 or 2, or when autodie is in effect. When set to 1, this will cause a warn with the error message; when set to 2, it will die. 2012 - EOF is excluded from auto_diag reports.
Errors can be (individually) caught using the error callback.
The errors described below are available. The original author tried to make each error explanatory enough, but more descriptions will be added. For most of these errors, the first three capitals describe the error category:
INI— Initialization error or option conflict.ECR— Carriage-Return related parse error.EOF— End-Of-File related parse error.EIQ— Parse error inside quotation.EIF— Parse error inside field.ECB— Combine error.EHR— HashRef parse related error.
And below should be the complete list of error codes that can be returned:
🚨 The full error-code menu 🚨
1001—"INI - sep_char is equal to quote_char or escape_char"— The separation character cannot be equal to the quotation character or to the escape character, because that would invalidate all parsing rules. 💀1002—"INI - allow_whitespace with escape_char or quote_char SP or TAB"— Using theallow_whitespaceattribute when eitherquote_charorescape_charis equal toSPACEorTABis too ambiguous to allow.1003—"INI - \r or \n in main attr not allowed"— Using defaulteolcharacters in eithersep_char,quote_char, orescape_charis not allowed.1004—"INI - callbacks should be undef or a hashref"— Thecallbacksattribute only allows one to beundefor a hash reference.1005—"INI - EOL too long"— The value passed for EOL is exceeding its maximum length (16).1006—"INI - SEP too long"— The value passed for SEP is exceeding its maximum length (16).1007—"INI - QUOTE too long"— The value passed for QUOTE is exceeding its maximum length (16).1008—"INI - SEP undefined"— The value passed for SEP should be defined and not empty.1010—"INI - the header is empty"— The header line parsed in theheaderis empty.1011—"INI - the header contains more than one valid separator"— The header line parsed in theheadercontains more than one (unique) separator character out of the allowed set of separators.1012—"INI - the header contains an empty field"— The header line parsed in theheadercontains an empty field.1013—"INI - the header contains nun-unique fields"— The header line parsed in theheadercontains at least two identical fields. (yes, it says “nun-unique” in the original — we keep the exact string 💅)1014—"INI - header called on undefined stream"— The header line cannot be parsed from an undefined source.1500—"PRM - Invalid/unsupported argument(s)"— Function or method called with invalid argument(s) or parameter(s).1501—"PRM - The key attribute is passed as an unsupported type"— Thekeyattribute is of an unsupported type.1502—"PRM - The value attribute is passed without the key attribute"— Thevalueattribute is only allowed when a valid key is given.1503—"PRM - The value attribute is passed as an unsupported type"— Thevalueattribute is of an unsupported type.2010—"ECR - QUO char inside quotes followed by CR not part of EOL"— Wheneolhas been set to anything but the default, like\r\t\n, and the\ris following the second (closing)quote_char, where the characters following the\rdo not make up theeolsequence, this is an error.2011—"ECR - Characters after end of quoted field"— Sequences like1,foo,"bar"baz,22,1are not allowed."bar"is a quoted field, and after the closing double-quote, there should be either a new-line sequence or a separation character.2012—"EOF - End of data in parsing input stream"— Self-explaining. End-of-file while inside parsing a stream. Can happen only when reading from streams withgetline, as usingparseis done on strings that are not required to have a trailingeol.2013—"INI - Specification error for fragments RFC7111"— Invalid specification for URIfragmentspecification.2014—"ENF - Inconsistent number of fields"— Inconsistent number of fields under strict parsing.2015—"ERW - Empty row"— An empty row was not allowed.2016—"EOL - Inconsistent EOL"— Inconsistent End-Of-Line detected under strict_eol parsing.2021—"EIQ - NL char inside quotes, binary off"— Sequences like1,"foo\nbar",22,1are allowed only when the binary option has been selected with the constructor.2022—"EIQ - CR char inside quotes, binary off"— Sequences like1,"foo\rbar",22,1are allowed only when the binary option has been selected with the constructor.2023—"EIQ - QUO character not allowed"— Sequences like"foo "bar" baz",qu"and2023,",2008-04-05,"Foo, Bar",\nwill cause this error.2024—"EIQ - EOF cannot be escaped, not even inside quotes"— The escape character is not allowed as last character in an input stream.2025—"EIQ - Loose unescaped escape"— An escape character should escape only characters that need escaping. Allowing the escape for other characters is possible with the attributeallow_loose_escapes.2026—"EIQ - Binary character inside quoted field, binary off"— Binary characters are not allowed by default. Exceptions are fields that contain valid UTF-8, that will automatically be upgraded if the content is valid UTF-8. Setbinaryto1to accept binary data.2027—"EIQ - Quoted field not terminated"— When parsing a field that started with a quotation character, the field is expected to be closed with a quotation character. When the parsed line is exhausted before the quote is found, that field is not terminated.2030—"EIF - NL char inside unquoted verbatim, binary off"2031—"EIF - CR char is first char of field, not part of EOL"2032—"EIF - CR char inside unquoted, not part of EOL"2034—"EIF - Loose unescaped quote"2035—"EIF - Escaped EOF in unquoted field"2036—"EIF - ESC error"2037—"EIF - Binary character in unquoted field, binary off"2110—"ECB - Binary character in Combine, binary off"2200—"EIO - print to IO failed. See errno"3001—"EHR - Unsupported syntax for column_names ()"3002—"EHR - getline_hr () called before column_names ()"3003—"EHR - bind_columns () and column_names () fields count mismatch"3004—"EHR - bind_columns () only accepts refs to scalars"3006—"EHR - bind_columns () did not pass enough refs for parsed fields"3007—"EHR - bind_columns needs refs to writable scalars"3008—"EHR - unexpected error in bound fields"3009—"EHR - print_hr () called before column_names ()"3010—"EHR - print_hr () called with invalid arguments"
🌈 SEE ALSO 🌈
IO::File, IO::Handle, IO::Wrap, Text::CSV, Text::CSV_PP, Text::CSV::Encoded, Text::CSV::Separator, Text::CSV::Slurp, Spreadsheet::CSV and Spreadsheet::Read, and of course perl.
If you are using Raku, have a look at Text::CSV in the Raku ecosystem, offering the same features.
🌍 non-perl 🌍
A CSV parser in JavaScript, also used by W3C (http://www.w3.org), is the multi-threaded in-browser PapaParse (http://papaparse.com/).
csvkit (http://csvkit.readthedocs.org) is a python CSV parsing toolkit.
👑 AUTHOR 👑
Alan Citterman (alan@mfgrtl.com) wrote the original Perl module. Please don't send mail concerning Text::CSV_XS to Alan, who is not involved in the C/XS part that is now the main part of the module. 🙈
Jochen Wiedmann (joe@ispsoft.de) rewrote the en- and decoding in C by implementing a simple finite-state machine. He added variable quote, escape and separator characters, the binary mode and the print and getline methods. See ChangeLog releases 0.10 through 0.23.
H.Merijn Brand (hmbrand@cpan.org) cleaned up the code, added the field flags methods, wrote the major part of the test suite, completed the documentation, fixed most RT bugs, added all the allow flags and the csv function. See ChangeLog releases 0.25 and on.
🎀 COPYRIGHT AND LICENSE 🎀
Copyright (C) 2007-2025 H.Merijn Brand. All rights reserved.
Copyright (C) 1998-2001 Jochen Wiedmann. All rights reserved.
Copyright (C) 1997 Alan Citterman. All rights reserved.This library is free software; you can redistribute and/or modify it under the same terms as Perl itself.
okay bestie, that’s the whole page! Footer vibes check: this is from perl v5.42.0, dated 2026-04-30, and the page is CSV_XS(3). Go forth and parse iconically 💅✨🦋
📦 where this page comes from
- opensuse-leap 16.0: perl-Text-CSV_XS 1.600.0-160000.3.1 · Artistic-1.0 OR GPL-1.0-or-later
- opensuse-leap 16.0: perl-Text-CSV_XS 1.600.0-160000.3.1 · Artistic-1.0 OR GPL-1.0-or-later
- opensuse-leap 16.0: perl-Text-CSV_XS 1.600.0-160000.3.1 · Artistic-1.0 OR GPL-1.0-or-later
- opensuse-leap 16.0: perl-Text-CSV_XS 1.600.0-160000.3.1 · Artistic-1.0 OR GPL-1.0-or-later
- 💖 girlified by deepseek-ai/DeepSeek-V4.1-Flash-1017 on : a language model's rewrite of the original, under its terms