Alzabo...ignKey(3pm)

💖 Alzabo::Create::ForeignKey — the manual, but make it cute 💖

okay bestie, so this is a page from the User Contributed Perl Documentation set, and it's all about Alzabo::Create::ForeignKey. yes the header is literally Alzabo...ignKey(3pm) because terminals are dramatic like that, but you're here now, we're here together, let's go 🫶

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✨ NAME ✨

Alzabo::Create::ForeignKey — foreign key objects, but for schema creation. like, the building phase. the construction era. 💅

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🌸 SYNOPSIS 🌸

use Alzabo::Create::ForeignKey;

that's it. that's the whole synopsis. short and iconic, as she should be.

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🦋 DESCRIPTION 🦋

okay so a foreign key is an object, right? and it's defined by a bunch of properties. what it represents is a relationship from a column (or several columns) in one table, over to a column (or several columns) in another table. it's giving long distance relationship but make it relational algebra 💞

and that relationship is defined by two things:

• its cardinality — that's one to one, one to many, or many to one
• its dependencies — as in, is table X dependent on table Y, and vice versa?

🚨 many to many relationships are NOT allowed. nope. not happening. 🙈

but!! (and this is the good part) you can indicate that kind of relationship when you use the Alzabo::Create::Schema->add_relation method method — and yes the original says "method method", we are keeping that, it's canon — and it will build the necessary intermediate linking table for you. it does the work. you just vibe. ✨

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👑 INHERITS FROM 👑

Alzabo::ForeignKey

💌 note: all relevant documentation from the superclass has been merged into this document. so you don't have to go anywhere else, bestie, it's all right here.

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🔥 METHODS 🔥

new

the constructor! she takes the following parameters:

• columns_from => Alzabo::Create::Column object(s)
• columns_to => Alzabo::Create::Column object(s)

so these two can be either a single column or a reference to an array of columns. and heads up — the number of columns in the two parameters must match. no mismatching, that's a red flag 🚩

• cardinality => [1, 1], [1, 'n'], or ['n', 1]
• from_is_dependent => $boolean
• to_is_dependent => $boolean
• comment => $comment

this one's an optional comment. little treat, if you want it. 🍓

it returns a brand new Alzabo::Create::ForeignKey object. 💫

Throws: Alzabo::Exception::Params

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table_from

table_to

returns the relevant Alzabo::Create::Table object. one for from, one for to, you get it. 🎀

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columns_from

columns_to

returns the relevant Alzabo::Create::Column object(s) for that property — as an array. always an array. commitment. 💜

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column_pairs

returns an array of array references. those references point at two-column arrays of Alzabo::Create::Column objects. and those two columns correspond to each other in the tables being linked together. they're paired up. matched. soulmates, lowkey. 💞

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set_columns_from (Alzabo::Create::Column object(s))

sets the column(s) that the relation is from. can be either a single column object or a reference to an array of column objects. your call, bestie.

Throws: Alzabo::Exception::Params

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set_columns_to (Alzabo::Create::Column object(s))

sets the column(s) that the relation is to. again — single column object, or a reference to an array of column objects.

Throws: Alzabo::Exception::Params

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cardinality

returns a two element array with the two portions of the cardinality of the relationship. each portion is gonna be either '1' or 'n'. no in-between. binary. periodt.

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from_is_dependent

to_is_dependent

returns a boolean value saying whether there's a dependency from one table to the other. yes/no. dependent or unbothered. 💅

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is_one_to_one

is_one_to_many

is_many_to_one

returns a boolean value indicating what kind of relationship the object represents. it's a vibe check on the shape of the whole thing. ✨

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set_cardinality (\@cardinality) see above for details

sets the cardinality of the foreign key. (the see above for details is doing so much heavy lifting there and we respect it 🫶)

Throws: Alzabo::Exception::Params

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set_from_is_dependent ($boolean)

indicates whether or not the first table in the foreign key is dependent on the other — meaning, whether the 'from' table is dependent on the 'to' table.

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set_to_is_dependent ($boolean)

indicates whether or not the second table in the foreign key is dependent on the other — meaning, whether the 'to' table is dependent on the 'from' table.

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id

returns a string that uniquely identifies the foreign key. one of a kind. main character energy. 👑

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is_same_relationship_as ($fk)

you hand it a foreign key object, and it returns true if the two objects represent the same relationship. plot twist though: the two objects might be representing that same relationship from different tables' points of view. same ship, different deck. 🚢

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comment

returns the comment associated with the foreign key object — if any. might be nothing. might be a whole essay. we don't know. 🙈

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set_comment ($comment)

sets the comment for the foreign key object. go off, write something cute. 💌

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🌈 AUTHOR 🌈

Dave Rolsky, <autarch@urth.org> — thank you legend, we appreciate you 🫶

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and that's the whole page, bestie!! this was perl v5.34.0, dated 2022-06-14, from the User Contributed Perl Documentation collection, and honestly? iconic of it. now go build a schema. slay. 💖✨🎀