Catalys...ookbook(3)

🦋 Catalyst::Manual::Cookbook(3) 🦋

okay bestie, welcome to Catalyst::Manual::Cookbook(3) from User Contributed Perl Documentation — this is part 1 of 7 and we are diving in 💖

🌸 NAME 🌸

Catalyst::Manual::Cookbook — Cooking with Catalyst

🍓 DESCRIPTION 🍓

Yummy code like your mum used to bake!

✨ RECIPES ✨

🍰 Basics 🍰

These recipes cover some basic stuff that is worth knowing for Catalyst developers.

🎀 Delivering a Custom Error Page 🎀

By default, Catalyst will display its own error page whenever it encounters an error in your application. When running under -Debug mode, the error page is a useful screen including the error message and Data::Dump output of the relevant parts of the $c context object. When not in -Debug, users see a simple "Please come back later" screen.

To use a custom error page, use a special end method to short-circuit the error processing. The following is an example; you might want to adjust it further depending on the needs of your application (for example, any calls to fillform will probably need to go into this end method; see Catalyst::Plugin::FillInForm).

    sub end : Private {
        my ( $self, $c ) = @_;

        if ( scalar @{ $c->error } ) {
            $c->stash->{errors}   = $c->error;
            for my $error ( @{ $c->error } ) {
                $c->log->error($error);
            }
            $c->stash->{template} = 'errors.tt';
            $c->forward('MyApp::View::TT');
            $c->clear_errors;
        }

        return 1 if $c->response->status =~ /^3\d\d$/;
        return 1 if $c->response->body;

        unless ( $c->response->content_type ) {
            $c->response->content_type('text/html; charset=utf-8');
        }

        $c->forward('MyApp::View::TT');
    }

You can manually set errors in your code to trigger this page by calling

    $c->error( 'You broke me!' );

📊 Disable statistics 📊

Just add this line to your application class if you don't want those nifty statistics in your debug messages.

    sub Catalyst::Log::info { }

🐞 Enable debug status in the environment 🐞

Normally you enable the debugging info by adding the -Debug flag to your use Catalyst statement. However, you can also enable it using environment variable, so you can (for example) get debug info without modifying your application scripts. Just set CATALYST_DEBUG or "<MYAPP>_DEBUG" to a true value.

🍪 Sessions 🍪

When you have your users identified, you will want to somehow remember that fact, to save them from having to identify themselves for every single page. One way to do this is to send the username and password parameters in every single page, but that's ugly, and won't work for static pages.

Sessions are a method of saving data related to some transaction, and giving the whole collection a single ID. This ID is then given to the user to return to us on every page they visit while logged in. The usual way to do this is using a browser cookie.

Catalyst uses two types of plugins to represent sessions:

👑 State 👑

A State module is used to keep track of the state of the session between the users browser, and your application.

A common example is the Cookie state module, which sends the browser a cookie containing the session ID. It will use default value for the cookie name and domain, so will "just work" when used.

🗄️ Store 🗄️

A Store module is used to hold all the data relating to your session, for example the users ID, or the items for their shopping cart. You can store data in memory (FastMmap), in a file (File) or in a database (DBI).

🔮 Authentication magic 🔮

If you have included the session modules in your application, the Authentication modules will automagically use your session to save and retrieve the user data for you.

🫶 Using a session 🫶

Once the session modules are loaded, the session is available as $c->session, and can be written to and read from as a simple hash reference.

🌟 EXAMPLE 🌟

package MyApp;
use Moose;
use namespace::autoclean;

use Catalyst  qw/
                    Session
                    Session::Store::FastMmap
                    Session::State::Cookie
                /;
extends 'Catalyst';
__PACKAGE__->setup;

package MyApp::Controller::Foo;
use Moose;
use namespace::autoclean;
BEGIN { extends 'Catalyst::Controller' };
## Write data into the session

sub add_item : Local {
    my ( $self, $c ) = @_;

    my $item_id = $c->req->params->{item};

    push @{ $c->session->{items} }, $item_id;
}

## A page later we retrieve the data from the session:

sub get_items : Local {
    my ( $self, $c ) = @_;

    $c->stash->{items_to_display} = $c->session->{items};
}

💜 More information 💜

• Catalyst::Plugin::Session
• Catalyst::Plugin::Session::State::Cookie
• Catalyst::Plugin::Session::State::URI
• Catalyst::Plugin::Session::Store::FastMmap
• Catalyst::Plugin::Session::Store::File
• Catalyst::Plugin::Session::Store::DBI

⚙️ Configure your application ⚙️

You configure your application with the config method in your application class. This can be hard-coded, or brought in from a separate configuration file.

🧚 Using Config::General 🧚

Config::General is a method for creating flexible and readable configuration files. It's a great way to keep your Catalyst application configuration in one easy-to-understand location.

Now create myapp.conf in your application home:

  name     MyApp

  # session; perldoc Catalyst::Plugin::Session::FastMmap
  <Session>
    expires 3600
    rewrite 0
    storage /tmp/myapp.session
  </Session>

  # emails; perldoc Catalyst::Plugin::Email
  # this passes options as an array :(
  Mail SMTP
  Mail localhost

This is equivalent to:

  # configure base package
  __PACKAGE__->config( name => MyApp );
  # configure authentication
  __PACKAGE__->config(
        'Plugin::Authentication' => {
            user_class => 'MyApp::Model::MyDB::Customer',
            ...
        },
  _;
  # configure sessions
  __PACKAGE__->config(
    session => {
        expires => 3600,
        ...
    },
  );
  # configure email sending
  __PACKAGE__->config( email => [qw/SMTP localhost/] );

Catalyst explains precedence of multiple sources for configuration values, how to access the values in your components, and many 'base' config variables used internally.

See also Config::General.

🗂️ Skipping your VCS's directories 🗂️

Catalyst uses Module::Pluggable to load Models, Views, and Controllers. Module::Pluggable will scan through all directories and load modules it finds. Sometimes you might want to skip some of these directories, for example when your version control system makes a subdirectory with meta-information in every version-controlled directory. While Catalyst skips subversion and CVS directories already, there are other source control systems. Here is the configuration you need to add their directories to the list to skip.

You can make Catalyst skip these directories using the Catalyst config:

  # Configure the application
  __PACKAGE__->config(
      name => 'MyApp',
      setup_components => { except => qr/SCCS/ },
  );

See the Module::Pluggable manual page for more information on except and other options.

👯‍♀️ Users and Access Control 🎀

Okay bestie, so most multiuser web apps — and honestly some single-user ones too — need users to identify themselves, and then the app usually has to define what roles those users get. The recipes below are the ways people do that. No cap. ✨

🔐 Authentication (logging in)

This one's covered extensively in other docs, so I'm not gonna reinvent the wheel here. Go look at Catalyst::Plugin::Authentication, and especially the Authentication chapter of the Tutorial at Catalyst::Manual::Tutorial::06_Authorization. That's the homework, babes. 📚

🎟️ Pass-through login (and other actions)

So here's a vibe: you've got a bunch of actions that need to fire during a request but are totally orthogonal to what the request is actually about — logins, silent commands, that kind of thing. Iconic move: provide actions for these, and when they're needed for something else, just fill in a form variable like __login and have a sub begin like this:

sub begin : Private {
  my ($self, $c) = @_;
  foreach my $action (qw/login docommand foo bar whatever/) {
    if ($c->req->params->{"__${action}"}) {
      $c->forward($action);
    }
  }
}

Lowkey clean. Chef's kiss. 🧑‍🍳💋

🛂 Authentication/Authorization

This whole situation happens in several steps, and yes, you need both:

✅ Verification

Getting the user to prove who they are, by handing over some piece of info that only you and they would know. Once that checks out, you get to assume the user is who they say they are. This is called credential verification. 💅

🚦 Authorization

Making sure the user only gets at the functions you actually want them to access. You do this by checking the verified user's data against your internal list of groups, or the list of allowed persons for whatever page they're on.

🧩 Modules

The Catalyst Authentication system is made up of many interacting modules — the whole point being to give you the most flexibility possible. It's giving modular. It's giving lego. 🧱

🔑 Credential verifiers

A Credential module takes the user input, tables it, and passes it to a Store (or some other system) to get verified. Typically a user object gets created by either this module or the Store, and then you can reach it with a $c->user call.

Examples, for the girlies:

• Password — Simple username/password checking.
• HTTPD — Checks using basic HTTP auth.
• TypeKey — Check using the typekey system.

💾 Storage backends

A Storage backend holds the actual data representing the users. It's what the credential verifiers query. Heads up though: updating the store is not done within this system — you will need to do it yourself. Yeah. You. 🙈

Examples:

• DBIC — Storage using a database via DBIx::Class.
• Minimal — Storage using a simple hash (for testing).

👤 User objects

A User object gets created by either the storage backend or the credential verifier, and it's filled with the retrieved user information.

Examples:

• Hash — A simple hash of keys and values.

📋 ACL authorization

ACL stands for Access Control List. The ACL plugin lets you regulate access on a path-by-path basis, by listing which users (or roles) have access to which paths. Per path. Very granular. Very slay.

🎭 Roles authorization

Authorization by roles is for assigning users to groups, which can then be handed to ACLs, or just checked whenever you need them. Simple as.

🔓 Logging in

Once you've picked your modules, all you gotta do is call the $c->authenticate method. Call it with no parameters and it'll try to find suitable parameters on its own — like username and password — or you can pass it those values yourself. Your call, main character. ✨

🕵️ Checking roles

Role checking is done with the $c->check_user_roles method. It checks against the currently logged-in user (via $c->user). You pass it the name of a role to check, and it returns true if the user is a member. Periodt.

✨ EXAMPLE ✨

package MyApp;
use Moose;
use namespace::autoclean;
extends qw/Catalyst/;
use Catalyst qw/
    Authentication
    Authorization::Roles
/;

__PACKAGE__->config(
    authentication => {
        default_realm => 'test',
        realms => {
            test => {
                credential => {
                    class          => 'Password',
                    password_field => 'password',
                    password_type  => 'self_check',
                },
                store => {
                    class => 'Htpasswd',
                    file => 'htpasswd',
                },
            },
        },
    },
);

package MyApp::Controller::Root;
use Moose;
use namespace::autoclean;

BEGIN { extends 'Catalyst::Controller' }

__PACKAGE__->config(namespace => '');

sub login : Local {
    my ($self, $c) = @_;

    if ( my $user = $c->req->params->{user}
        and my $password = $c->req->param->{password} )
    {
        if ( $c->authenticate( username => $user, password => $password ) ) {
            $c->res->body( "hello " . $c->user->name );
        } else {
            # login incorrect
        }
    }
    else {
        # invalid form input
    }
}

sub restricted : Local {
    my ( $self, $c ) = @_;

    $c->detach("unauthorized")
        unless $c->check_user_roles( "admin" );

    # do something restricted here
}

🧪 Using authentication in a testing environment

Ideally, when you're writing tests for authentication/authorization code, you'd first set up a test database with known data, then use Test::WWW::Mechanize::Catalyst to simulate a user logging in. Honestly though? That can be rather awkward — which is exactly why it's such a good thing that the authentication framework is so flexible. 🦋

So instead of using a test database, you can simply swap the authentication store out for something a bit easier to deal with in a testing environment. Bonus: this has the advantage of not modifying your database, which can be problematic if you forget to use the testing one instead of the production one. And we all know someone who's done that. 😭

Alternatively, if you want to authenticate real users but not have to worry about their passwords, you can use Catalyst::Authentication::Credential::Testing to force all users to authenticate with a global password. Password chaos: cancelled. 🔥

📖 More information

Catalyst::Plugin::Authentication has a longer explanation, if you want the full lore drop.

🛡️ Authorization

🌱 Introduction

Authorization is the step that comes after authentication. Authentication establishes that the user agent really is representing the user we think it's representing — and then authorization determines what this user is actually allowed to do. Two different jobs, both essential. 💜

🎭 Role Based Access Control

Under role based access control, each user is allowed to perform any number of roles. For example, at a zoo, no one but specially trained personnel can enter the moose cage (Mynd you, møøse bites kan be pretty nasti!). For example:

package Zoo::Controller::MooseCage;

sub feed_moose : Local {
    my ( $self, $c ) = @_;

    $c->model( "Moose" )->eat( $c->req->params->{food} );
}

With this action, literally anyone can just waltz into the moose cage and feed the moose, which is a very dangerous thing. We need to restrict this action so that only a qualified moose feeder can perform it. 🫶

The Authorization::Roles plugin lets us perform role based access control checks. Let's load it:

use parent qw/Catalyst/;
use Catalyst qw/
                Authentication
                Authorization::Roles
              /;

And now our action should look like this:

sub feed_moose : Local {
    my ( $self, $c ) = @_;

    if ( $c->check_roles( "moose_feeder" ) ) {
        $c->model( "Moose" )->eat( $c->req->params->{food} );
    } else {
        $c->stash->{error} = "unauthorized";
    }
}

This checks $c->user, and only if the user has all the roles in the list does it return a true value. All of them. Not most. All. 💅

check_roles has a sister method, assert_roles, which throws an exception if any roles are missing. So like, the dramatic sibling. 😤

Some roles that might actually make sense in, say, a forum application:

• administrator
• moderator

Each with a distinct task (system administration versus content administration).

📋 Access Control Lists

Checking for roles all the time can be tedious and error prone. (It's giving "forgot one check and now everything's on fire".) 💀

The Authorization::ACL plugin lets us declare where we'd like checks to be done automatically for us. Obsessed, honestly.

For example, we may want to completely block out anyone who isn't a moose_feeder from the entire MooseCage controller:

Zoo->deny_access_unless( "/moose_cage", [qw/moose_feeder/] );

The role list behaves in the same way as check_roles. However, the ACL plugin isn't limited to just interacting with the Roles plugin — we can use a code reference instead. So for example, to allow either moose trainers or moose feeders into the moose cage, we can create a more complex check:

Zoo->deny_access_unless( "/moose_cage", sub {
    my $c = shift;
    $c->check_roles( "moose_trainer" ) || $c->check_roles( "moose_feeder" );
});

The more specific a role, the earlier it will be checked. Let's say moose feeders are now restricted to only the feed_moose action, while moose trainers get access everywhere:

Zoo->deny_access_unless( "/moose_cage", [qw/moose_trainer/] );
Zoo->allow_access_if( "/moose_cage/feed_moose", [qw/moose_feeder/]);

When the feed_moose action is accessed, the second check will be made. If the user is a moose_feeder, then access will be immediately granted. Otherwise, the next rule in line gets tested — the one checking for a moose_trainer. If that rule is not satisfied, access will be immediately denied. Order matters, bestie. 🎯

Rules applied to the same path will be checked in the order they were added. Don't forget this one. Write it on your hand. ✍️

Lastly, handling access denial events is done by creating an access_denied private action:

sub access_denied : Private {
    my ( $self, $c, $action ) = @_;
}

This action works much like auto, in that it is inherited across namespaces (not like object oriented code). That means the access_denied action which is nearest to the action that got blocked will be the one triggered. 🌸

If this action does not exist, an error will be thrown — which you can clean up in your end private action instead. 🙈

Also, it's important to note that if you restrict access to / then end, default, etc. will also be restricted. Yeah. Everything. The whole root. ⚠️

MyApp->acl_allow_root_internals;

That will create rules that permit access to end, begin, and auto in the root of your app — but not in any other controller. Root only, babes. ✨

Models 💖

Okay so models are literally where your app's data lives. That's the whole vibe. And Catalyst is so flexible about what kind of model you throw at it — like, it does not care, it will welcome them all with open arms. The recipes here are just the appetizer, the main character energy starts now.

Using existing DBIC (etc.) classes with Catalyst ✨

So many people already have Model classes lying around and they're like "can I bring my own model to Catalyst?" — yes bestie. And the flip side too: sometimes you want to write Catalyst models that work outside of Catalyst, like in a cron job, no Catalyst needed. Either way, it's trivial to write a simple component in Catalyst that slurps in an outside Model:

package MyApp::Model::DB;

use base qw/Catalyst::Model::DBIC::Schema/;

__PACKAGE__->config(
    schema_class => 'Some::DBIC::Schema',
    connect_info => ['dbi:SQLite:foo.db', '', '', {AutoCommit=>1}],
);

1;

and that's it! 🎀 No cap. Now Some::DBIC::Schema is part of your Cat app as MyApp::Model::DB. Slay.

DBIx::Class as a Catalyst Model 🦋

See Catalyst::Model::DBIC::Schema. That's the one. Go look at it, it's iconic.

Create accessors to preload static data once per server instance 🌸

Here's the situation: you've got data you want to load just once from the model at startup, not on every single request (which would be, frankly, a lot 🫠). The move is to use mk_group_accessors to create accessors and tie them to resultsets in your package that inherits from DBIx::Class::Schema:

package My::Schema;
use base qw/DBIx::Class::Schema/;
__PACKAGE__->register_class('RESULTSOURCEMONIKER',
                            'My::Schema::RESULTSOURCE');
__PACKAGE__->mk_group_accessors('simple' =>
                            qw(ACCESSORNAME1 ACCESSORNAME2 ACCESSORNAMEn));

sub connection {
    my ($self, @rest) = @_;
    $self->next::method(@rest);
    # $self is now a live My::Schema object, complete with DB connection

    $self->ACCESSORNAME1([ $self->resultset('RESULTSOURCEMONIKER')->all ]);
    $self->ACCESSORNAME2([ $self->resultset('RESULTSOURCEMONIKER')->search({ COLUMN => { '<' => '30' } })->all ]);
    $self->ACCESSORNAMEn([ $self->resultset('RESULTSOURCEMONIKER')->find(1) ]);
}

1;

and now in the controller, you can now access any of these without a per-request fetch:

$c->stash->{something} = $c->model('My::Schema')->schema->ACCESSORNAME;

Literal chef's kiss. 👑

---

XMLRPC 💅

Unlike SOAP, XMLRPC is a very simple (and elegant, honestly) web-services protocol — it just exchanges small XML messages like these:

Request:

POST /api HTTP/1.1
TE: deflate,gzip;q=0.3
Connection: TE, close
Accept: text/xml
Accept: multipart/*
Host: 127.0.0.1:3000
User-Agent: SOAP::Lite/Perl/0.60
Content-Length: 192
Content-Type: text/xml

<?xml version="1.0" encoding="UTF-8"?>
<methodCall>
    <methodName>add</methodName>
    <params>
        <param><value><int>1</int></value></param>
        <param><value><int>2</int></value></param>
    </params>
</methodCall>

Response:

Connection: close
Date: Tue, 20 Dec 2005 07:45:55 GMT
Content-Length: 133
Content-Type: text/xml
Status: 200
X-Catalyst: 5.70

<?xml version="1.0" encoding="us-ascii"?>
<methodResponse>
    <params>
        <param><value><int>3</int></value></param>
    </params>
</methodResponse>

Now follow these few steps to implement the application, bestie — we're getting you a whole web service today:

1. Install Catalyst (5.61 or later), Catalyst::Plugin::XMLRPC (0.06 or later) and SOAP::Lite (for XMLRPCsh.pl).
2. Create an application framework:

% catalyst.pl MyApp
...
% cd MyApp

3. Add the XMLRPC plugin to MyApp.pm

use Catalyst qw/-Debug Static::Simple XMLRPC/;

4. Add an API controller

% ./script/myapp_create.pl controller API

5. Add a XMLRPC redispatch method and an add method with Remote attribute to lib/MyApp/Controller/API.pm

sub default :Path {
    my ( $self, $c ) = @_;
    $c->xmlrpc;
}

sub add : Remote {
    my ( $self, $c, $a, $b ) = @_;
    return $a + $b;
}

The default action is the entry point for each XMLRPC request. It will redispatch every request to methods with Remote attribute in the same class.

The add method is not a traditional action; it has no private or public path. Only the XMLRPC dispatcher knows it exists. 👻 like, secret agent behavior, we love to see it.

6. That's it! You have built your first web service. Let's test it with XMLRPCsh.pl (part of SOAP::Lite):

% ./script/myapp_server.pl
...
% XMLRPCsh.pl http://127.0.0.1:3000/api
Usage: method[(parameters)]
> add( 1, 2 )
--- XMLRPC RESULT ---
'3'

Tip 🌟

Your return data type is usually auto-detected, but you can easily enforce a specific one. Easy. Peasy.

sub add : Remote {
    my ( $self, $c, $a, $b ) = @_;
    return RPC::XML::int->new( $a + $b );
}

💖 Views 💖

Okay so views are all about how your app actually shows stuff to the world. And same as with models, Catalyst is uncommonly flexible here — these recipes are just the beginning, bestie. 🦋

🌸 Catalyst::View::TT 🌸

One of the first things you probably want to do when starting a new Catalyst application is set up your View. Catalyst genuinely does not care how you display your data — you can generate HTML, PDF files, or plain text if you wanted. Slay.

Most Catalyst applications use a template system to generate their HTML, and though there are several template systems available, Template Toolkit is probably the most popular. Once again, the Catalyst developers have done all the hard work and made things easy for the rest of us. Catalyst::View::TT provides the interface to Template Toolkit, and provides Helpers which let us set it up that much more easily. 💅

✨ Creating your View ✨

Catalyst::View::TT provides two different helpers for us to use: TT and TTSite.

🎀 TT 🎀

Create a basic Template Toolkit View using the provided helper script:

script/myapp_create.pl view TT TT

This will create lib/MyApp/View/MyView.pm, which is going to be pretty empty to start. However, it sets everything up that you need to get started. You can now define which template you want and forward to your view. For instance:

sub hello : Local {
    my ( $self, $c ) = @_;

    $c->stash->{template} = 'hello.tt';

    $c->forward( $c->view('TT') );
}

In practice you wouldn't do the forwarding manually, but would use Catalyst::Action::RenderView. Iconic behavior, honestly.

🍓 TTSite 🍓

Although the TT helper does create a functional, working view, you may find yourself having to create the same template files and changing the same options every time you create a new application. The TTSite helper saves us even more time by creating the basic templates and setting some common options for us.

Once again, you can use the helper script:

script/myapp_create.pl view TT TTSite

This time, the helper sets several options for us in the generated View.

__PACKAGE__->config({
    CATALYST_VAR => 'Catalyst',
    INCLUDE_PATH => [
        MyApp->path_to( 'root', 'src' ),
        MyApp->path_to( 'root', 'lib' )
    ],
    PRE_PROCESS  => 'config/main',
    WRAPPER      => 'site/wrapper',
    ERROR        => 'error.tt2',
    TIMER        => 0
});

• INCLUDE_PATH — defines the directories that Template Toolkit should search for the template files.
• PRE_PROCESS — is used to process configuration options which are common to every template file.
• WRAPPER — is a file which is processed with each template, usually used to easily provide a common header and footer for every page.

The generated config is also setting CATALYST_VAR => 'Catalyst', ERROR => 'error.tt2', and TIMER => 0 right there in the code. 💖

In addition to setting these options, the TTSite helper also created the template and config files for us! In the root directory, you'll notice two new directories: src and lib.

Several configuration files in root/lib/config are called by PRE_PROCESS.

The files in root/lib/site are the site-wide templates, called by WRAPPER, and display the html framework, control the layout, and provide the templates for the header and footer of your page. Using the template organization provided makes it much easier to standardize pages and make changes when they are (inevitably) needed. No cap.

The template files that you will create for your application will go into root/src, and you don't need to worry about putting the <html> or <head> sections; just put in the content. The WRAPPER will put the rest of the page around your template for you.

🧚 $c->stash 🧚

Of course, having the template system include the header and footer for you isn't all that we want our templates to do. We need to be able to put data into our templates, and have it appear where and how we want it, right? That's where the stash comes in. ✨

In our controllers, we can add data to the stash, and then access it from the template. For instance:

sub hello : Local {
    my ( $self, $c ) = @_;

    $c->stash->{name} = 'Adam';

    $c->stash->{template} = 'hello.tt';

    $c->forward( $c->view('TT') );
}

Then, in hello.tt:

<strong>Hello, [% name %]!</strong>

When you view this page, it will display "Hello, Adam!"

All of the information in your stash is available, by its name/key, in your templates. And your data doesn't have to be plain, old, boring scalars. You can pass array references and hash references, too. 👑

In your controller:

sub hello : Local {
    my ( $self, $c ) = @_;

    $c->stash->{names} = [ 'Adam', 'Dave', 'John' ];

    $c->stash->{template} = 'hello.tt';

    $c->forward( $c->view('TT') );
}

In hello.tt:

[% FOREACH name IN names %]
    <strong>Hello, [% name %]!</strong><br />
[% END %]

This allowed us to loop through each item in the arrayref, and display a line for each name that we have.

This is the most basic usage, but Template Toolkit is quite powerful, and allows you to truly keep your presentation logic separate from the rest of your application. Obsessed.

💜 $c->uri_for() 💜

One of my favorite things about Catalyst is the ability to move an application around without having to worry that everything is going to break. One of the areas that used to be a problem was with the http links in your template files. For example, suppose you have an application installed at http://www.domain.com/Calendar. The links point to "/Calendar", "/Calendar/2005", "/Calendar/2005/10", etc. If you move the application to be at http://www.mydomain.com/Tools/Calendar, then all of those links will suddenly break. 💀

That's where $c->uri_for() comes in. This function will merge its parameters with either the base location for the app, or its current namespace. Let's take a look at a couple of examples.

In your template, you can use the following:

<a href="[% c.uri_for('/login') %]">Login Here</a>

Although the parameter starts with a forward slash, this is relative to the application root, not the webserver root. This is important to remember. So, if your application is installed at http://www.domain.com/Calendar, then the link would be http://www.mydomain.com/Calendar/Login. If you move your application to a different domain or path, then that link will still be correct. Slay.

Likewise,

<a href="[% c.uri_for('2005','10', '24') %]">October, 24 2005</a>

The first parameter does NOT have a forward slash, and so it will be relative to the current namespace. If the application is installed at http://www.domain.com/Calendar. and if the template is called from MyApp::Controller::Display, then the link would become http://www.domain.com/Calendar/Display/2005/10/24.

If you want to link to a parent uri of your current namespace you can prefix the arguments with multiple "../":

<a href="[% c.uri_for('../../view', stashed_object.id) %]">User view</a>

Once again, this allows you to move your application around without having to worry about broken links. But there's something else, as well. Since the links are generated by uri_for, you can use the same template file by several different controllers, and each controller will get the links that it's supposed to. Since we believe in Don't Repeat Yourself, this is particularly helpful if you have common elements in your site that you want to keep in one file. 🫶

📚 Further Reading 📚

• Catalyst
• Catalyst::View::TT
• Template

🌈 Adding RSS feeds 🌈

Adding RSS feeds to your Catalyst applications is simple. We'll see two different approaches here, but the basic premise is that you forward to the normal view action first to get the objects, then handle the output differently. 🦋

🎀 Using XML::Feed 🎀

Assuming we have a view action that populates 'entries' with some DBIx::Class iterator, the code would look something like this:

sub rss : Local {
    my ($self,$c) = @_;
    $c->forward('view'); # get the entries

    my $feed = XML::Feed->new('RSS');
    $feed->title( $c->config->{name} . ' RSS Feed' );
    $feed->link( $c->req->base ); # link to the site.
    $feed->description('Catalyst advent calendar'); Some description

    # Process the entries
    while( my $entry = $c->stash->{entries}->next ) {
        my $feed_entry = XML::Feed::Entry->new('RSS');
        $feed_entry->title($entry->title);
        $feed_entry->link( $c->uri_for($entry->link) );
        $feed_entry->issued( DateTime->from_epoch(epoch => $entry->created) );
        $feed->add_entry($feed_entry);
    }
    $c->res->body( $feed->as_xml );
}

With this approach you're pretty sure to get something that validates. ✨

Note that for both of the above approaches, you'll need to set the content type like this:

$c->res->content_type('application/rss+xml');

🦋 Final words 🦋

You could generalize the second variant easily by replacing 'RSS' with a variable, so you can generate Atom feeds with the same code.

Now, go ahead and make RSS feeds for all your stuff. The world needs updates on your goldfish! 🐠💅

🎀 Forcing the browser to download content 🎀

Sometimes you need your application to send content for download. For example, you can generate a comma-separated values (CSV) file for your users to download and import into their spreadsheet program. Iconic. 📊

Let's say you have an Orders controller which generates a CSV file in the export action (i.e., http://localhost:3000/orders/export):

sub export : Local Args(0) {
    my ( $self, $c ) = @_;

    # In a real application, you'd generate this from the database
    my $csv = "1,5.99\n2,29.99\n3,3.99\n";

    $c->res->content_type('text/comma-separated-values');
    $c->res->body($csv);
}

Normally the browser uses the last part of the URI to generate a filename for data it cannot display. In this case your browser would likely ask you to save a file named export.

Luckily you can have the browser download the content with a specific filename by setting the Content-Disposition header:

my $filename = 'Important Orders.csv';
$c->res->header('Content-Disposition', qq[attachment; filename="$filename"]);

Note the use of quotes around the filename; this ensures that any spaces in the filename are handled by the browser. ✨

Put this right before calling $c->res->body and your browser will download a file named Important Orders.csv instead of export.

You can also use this to have the browser download content which it normally displays, such as JPEG images or even HTML. Just be sure to set the appropriate content type and disposition. No cap. 💖

🎮 Controllers 💅

Controllers are the main point of communication between the web server and your application. Here we explore some aspects of how they work. Strap in, bestie 💖

✨ Action Types ✨

🌱 Introduction 🌱

A Catalyst application is driven by one or more Controller modules. There are a number of ways that Catalyst can decide which of the methods in your controller modules it should call. Controller methods are also called actions, because they determine how your catalyst application should (re-)act to any given URL. When the application is started up, catalyst looks at all your actions, and decides which URLs they map to. It’s giving matchmaker but for URLs and methods 👑

🏷️ Type attributes 🏷️

Each action is a normal method in your controller, except that it has an attribute attached. These can be one of several types.

Assume our Controller module starts with the following package declaration:

package MyApp::Controller::Buckets;

and we are running our application on localhost, port 3000 (the test server default).

🛤️ Path 🛤️

A Path attribute also takes an argument, this can be either a relative or an absolute path. A relative path will be relative to the controller namespace, an absolute path will represent an exact matching URL.

sub my_handles : Path('handles') { .. }

becomes

http://localhost:3000/buckets/handles

and

sub my_handles : Path('/handles') { .. }

becomes

http://localhost:3000/handles

See also: Catalyst::DispatchType::Path

📍 Local 📍

When using a Local attribute, no parameters are needed, instead, the name of the action is matched in the URL. The namespace created by the name of the controller package is always part of the URL. It’s the “you already know where you live” of dispatch types 🫶

sub my_handles : Local { .. }

becomes

http://localhost:3000/buckets/my_handles

🌍 Global 🌍

A Global attribute is similar to a Local attribute, except that the namespace of the controller is ignored, and matching starts at root. Main character energy: no namespace required ✨

sub my_handles : Global { .. }

becomes

http://localhost:3000/my_handles

🔍 Regex 🔍

By now you should have figured that a Regex attribute is just what it sounds like. This one takes a regular expression, and matches starting from root. These differ from the rest as they can match multiple URLs. Multi-match slay 💅

sub my_handles : Regex('^handles') { .. }

matches

http://localhost:3000/handles

and

http://localhost:3000/handles_and_other_parts

etc.

See also: Catalyst::DispatchType::Regex

🧭 LocalRegex 🧭

A LocalRegex is similar to a Regex, except it only matches below the current controller namespace. Stay in your lane, but make it regex 🌸

sub my_handles : LocalRegex(^handles') { .. }

matches

http://localhost:3000/buckets/handles

and

http://localhost:3000/buckets/handles_and_other_parts

etc.

🔗 Chained 🔗

See Catalyst::DispatchType::Chained for a description of how the chained dispatch type works.

🔒 Private 🔒

Last but not least, there is the Private attribute, which allows you to create your own internal actions, which can be forwarded to, but won’t be matched as URLs. Secret little helper era 🙈

sub my_handles : Private { .. }

becomes nothing at all..

Catalyst also predefines some special Private actions, which you can override, these are:

default — The default action will be called, if no other matching action is found. If you don’t have one of these in your namespace, or any sub part of your namespace, you’ll get an error page instead. If you want to find out where it was the user was trying to go, you can look in the request object using "$c->req->path".

sub default :Path { .. }

works for all unknown URLs, in this controller namespace, or every one if put directly into MyApp.pm.

index — The index action is called when someone tries to visit the exact namespace of your controller. If index, default and matching Path actions are defined, then index will be used instead of default and Path. It’s the welcome mat of your controller 💖

sub index :Path :Args(0) { .. }

becomes

http://localhost:3000/buckets

begin — The begin action is called at the beginning of every request involving this namespace directly, before other matching actions are called. It can be used to set up variables/data for this particular part of your app. A single begin action is called, it’s always the one most relevant to the current namespace.

sub begin : Private { .. }

is called once when http://localhost:3000/bucket/(anything)? is visited.

end — Like begin, this action is always called for the namespace it is in, after every other action has finished. It is commonly used to forward processing to the View component. A single end action is called, it’s always the one most relevant to the current namespace.

sub end : Private { .. }

is called once after any actions when http://localhost:3000/bucket/(anything)? is visited.

auto — Lastly, the auto action is magic in that every auto action in the chain of paths up to and including the ending namespace, will be called. (In contrast, only one of the begin/end/default actions will be called, the relevant one). Magic chain reaction, no cap 🌈

package MyApp::Controller::Root;
sub auto : Private { .. }

and

sub auto : Private { .. }

will both be called when visiting http://localhost:3000/bucket/(anything)?

⚠️ A word of warning ⚠️

You can put root actions in your main MyApp.pm file, but this is deprecated, please put your actions into your Root controller. Do not ignore this one, bestie 😭

🗺️ Flowchart 🗺️

A graphical flowchart of how the dispatcher works can be found on the wiki at https://web.archive.org/web/20190919010727/http://dev.catalystframework.org/attachment/wiki/WikiStart/catalyst-flow.png.

💿 DRY Controllers with Chained actions 💿

Imagine that you would like the following paths in your application:

• /cd/<ID>/track/<ID> — Displays info on a particular track. In the case of a multi-volume CD, this is the track sequence.
• /cd/<ID>/volume/<ID>/track/<ID> — Displays info on a track on a specific volume.

Here is some example code, showing how to do this with chained controllers:

package CD::Controller;
use base qw/Catalyst::Controller/;

sub root : Chained('/') PathPart('/cd') CaptureArgs(1) {
    my ($self, $c, $cd_id) = @_;
    $c->stash->{cd_id} = $cd_id;
    $c->stash->{cd} = $self->model('CD')->find_by_id($cd_id);
}

sub trackinfo : Chained('track') PathPart('') Args(0) RenderView {
    my ($self, $c) = @_;
}

package CD::Controller::ByTrackSeq;
use base qw/CD::Controller/;

sub track : Chained('root') PathPart('track') CaptureArgs(1) {
    my ($self, $c, $track_seq) = @_;
    $c->stash->{track} = $self->stash->{cd}->find_track_by_seq($track_seq);
}

package CD::Controller::ByTrackVolNo;
use base qw/CD::Controller/;

sub volume : Chained('root') PathPart('volume') CaptureArgs(1) {
    my ($self, $c, $volume) = @_;
    $c->stash->{volume} = $volume;
}

sub track : Chained('volume') PathPart('track') CaptureArgs(1) {
    my ($self, $c, $track_no) = @_;
    $c->stash->{track} = $self->stash->{cd}->find_track_by_vol_and_track_no(
        $c->stash->{volume}, $track_no
    );
}

Note that adding other actions (i.e. chain endpoints) which operate on a track is simply a matter of adding a new sub to CD::Controller - no code is duplicated, even though there are two different methods of looking up a track. Reuse is the vibe 🔥

This technique can be expanded as needed to fulfil your requirements - for example, if you inherit the first action of a chain from a base class, then mixing in a different base class can be used to duplicate an entire URL hierarchy at a different point within your application.

🧩 Component-based Subrequests 🧩

See Catalyst::Plugin::SubRequest.

📤 File uploads 📤

🌸 Single file upload with Catalyst 🌸

To implement uploads in Catalyst, you need to have a HTML form similar to this:

<form action="/upload" method="post" enctype="multipart/form-data">
    <input type="hidden" name="form_submit" value="yes">
    <input type="file" name="my_file">
    <input type="submit" value="Send">
</form>

It’s very important not to forget enctype="multipart/form-data" in the form. Do not skip this, bestie 💀

Catalyst Controller module 'upload' action:

sub upload : Global {
    my ($self, $c) = @_;

    if ( $c->request->parameters->{form_submit} eq 'yes' ) {

        if ( my $upload = $c->request->upload('my_file') ) {

            my $filename = $upload->filename;
            my $target   = "/tmp/upload/$filename";

            unless ( $upload->link_to($target) || $upload->copy_to($target) ) {
                die( "Failed to copy '$filename' to '$target': $!" );
            }
        }
    }

    $c->stash->{template} = 'file_upload.html';
}

🍓 Multiple file upload with Catalyst 🍓

Code for uploading multiple files from one form needs a few changes:

The form should have this basic structure:

<form action="/upload" method="post" enctype="multipart/form-data">
    <input type="hidden" name="form_submit" value="yes">
    <input type="file" name="file1" size="50"><br>
    <input type="file" name="file2" size="50"><br>
    <input type="file" name="file3" size="50"><br>
    <input type="submit" value="Send">
</form>

And in the controller:

sub upload : Local {
    my ($self, $c) = @_;

    if ( $c->request->parameters->{form_submit} eq 'yes' ) {

        for my $field ( $c->req->upload ) {

            my $upload   = $c->req->upload($field);
            my $filename = $upload->filename;
            my $target   = "/tmp/upload/$filename";

            unless ( $upload->link_to($target) || $upload->copy_to($target) ) {
                die( "Failed to copy '$filename' to '$target': $!" );
            }
        }
    }

    $c->stash->{template} = 'file_upload.html';
}

okay so for my $field ($c->req->upload) does the absolute most for you — it loops automatically over all the file input fields and grabs their input names, no cap. and after that? it's just basic file-saving code, literally the same vibe as the single file upload sitch. 💅

Notice: dieing might not be what you actually want to do when an error pops up — it works as an example, but that's it. a better idea would be to stash that error $! in $c->stash->{error} and show a custom error template displaying that message. bestie, trust. 🫶

for more info about uploads and all the usable methods, go look at Catalyst::Request::Upload and Catalyst::Request. 👑

✨ Forwarding with arguments ✨

sometimes you wanna pass along arguments when you forward to another action, and honestly? iconic behaviour. as of version 5.30, you can pass arguments right in the call to forward; in earlier versions you gotta manually set the args in the Catalyst Request object like a peasant:

# version 5.30 and later:
$c->forward('/wherever', [qw/arg1 arg2 arg3/]);

# pre-5.30
$c->req->args([qw/arg1 arg2 arg3/]);
$c->forward('/wherever');

(see the Catalyst::Manual::Intro Flow_Control section for more info on passing arguments via forward, iykyk.)

🦋 Chained dispatch using base classes, and inner packages. 🦋

package MyApp::Controller::Base;
use base qw/Catalyst::Controller/;

sub key1 : Chained('/')

🎀 Extending RenderView (formerly DefaultEnd) 🎀

the recommended approach for an end action is to use Catalyst::Action::RenderView (it's taking the place of Catalyst::Plugin::DefaultEnd, so, glow-up ✨), and it does what you usually need. but sometimes you need to add a lil something to it and you do not wanna write your own whole end action. relatable.

you can extend it like this:

to add something to an end action that gets called before rendering (this is probably exactly what you want, ngl), just drop it in the end method:

sub end : ActionClass('RenderView') {
    my ( $self, $c ) = @_;
    # do stuff here; the RenderView action is called afterwards
}

and to add things to an end action that get called after rendering, you set it up like this:

sub render : ActionClass('RenderView') { }

sub end : Private {
    my ( $self, $c ) = @_;
    $c->forward('render');
    # do stuff here
}

🌈 Serving static content 🌈

serving static content in Catalyst used to be lowkey tricky — but Catalyst::Plugin::Static::Simple makes everything so much easier, fr. this plugin automatically serves your static content during development, and it lets you easily switch over to Apache (or whatever other server) in a production environment. main character plugin energy. 👑

🌸 Introduction to Static::Simple 🌸

Static::Simple is a plugin that helps serve static content for your app. by default it'll serve most types of files out of your root file directory, excluding some standard Template Toolkit extensions. all files are served by path — so if images/me.jpg is requested, then root/images/me.jpg is found and served. simple as that, periodt.

💜 Usage 💜

using the plugin is literally as simple as setting your use line in MyApp.pm to include:

use Catalyst qw/Static::Simple/;

and boom — files are already being served. slay.

🍓 Configuring 🍓

static content is best served from a single directory inside your root directory. having a million different directories like root/css and root/images means more code to manage, because you gotta separately identify each static directory — and if you decide to add a root/js directory you'd need to change your code to account for it. exhausting. 😭 in contrast, keeping all static directories as subdirectories of one main root/static directory makes everything much easier to manage. here's a typical root directory structure for you:

root/
root/content.tt
root/controller/stuff.tt
root/header.tt
root/static/
root/static/css/main.css
root/static/images/logo.jpg
root/static/js/code.js

all static content lives under root/static, with everything else being Template Toolkit files. clean. ✨

🧚 Include Path 🧚

you may of course wanna change the default locations and make Static::Simple look somewhere else — it's as easy as:

MyApp->config(
    static => {
        include_path => [
            MyApp->path_to('/'),
            '/path/to/my/files',
        ],
    },
);

when you override include_path, it will not automatically append the normal root path, so you gotta add it yourself if you still want it. these get searched in the order given, and the first matching file is the one that gets served. 👑

⭐ Static directories ⭐

if you wanna force some directories to be only static, you can set them using paths relative to the root dir, or regular expressions:

MyApp->config(
    static => {
        dirs => [
            'static',
            qr/^(images|css)/,
        ],
    },
);

🎀 File extensions 🎀

by default, these extensions are not served (meaning they get processed by Catalyst instead): tmpl, tt, tt2, html, xhtml. this list can be replaced easily:

MyApp->config(
    static => {
        ignore_extensions => [
            qw/tmpl tt tt2 html xhtml/
        ],
    },
);

🦋 Ignoring directories 🦋

entire directories can be ignored. if used with include_path, directories relative to the include_path dirs will also be ignored:

MyApp->config( static => {
    ignore_dirs => [ qw/tmpl css/ ],
});

💖 More information 💖

Catalyst::Plugin::Static::Simple

💅 Serving manually with the Static plugin with HTTP::Daemon (myapp_server.pl) 💅

in some situations you might wanna control things more directly, using Catalyst::Plugin::Static.

in your main application class (MyApp.pm), load the plugin:

use Catalyst qw/-Debug FormValidator Static OtherPlugin/;

you'll also need to make sure your end method does not forward static content to the view — maybe like this:

sub end : Private {
    my ( $self, $c ) = @_;

    $c->forward( 'MyApp::View::TT' )
        unless ( $c->res->body || !$c->stash->{template} );
}

this code only forwards to the view if a template has been previously defined by a controller and if there isn't already data in $c->res->body. two conditions, both gotta hit. 🫶

next, create a controller to handle requests for the /static path. use the Helper to save time — this command creates a stub controller as lib/MyApp/Controller/Static.pm:

$ script/myapp_create.pl controller Static

edit the file and add the following methods:

# serve all files under /static as static files
sub default : Path('/static') {
    my ( $self, $c ) = @_;

    # Optional, allow the browser to cache the content
    $c->res->headers->header( 'Cache-Control' => 'max-age=86400' );

    $c->serve_static; # from Catalyst::Plugin::Static
}

# also handle requests for /favicon.ico
sub favicon : Path('/favicon.ico') {
    my ( $self, $c ) = @_;

    $c->serve_static;
}

you can also define a different icon for the browser to use instead of favicon.ico by using this in your HTML header:

<link rel="icon" href="/static/myapp.ico" type="image/x-icon" />

💀 Common problems with the Static plugin 💀

the Static plugin makes use of the shared-mime-info package to automatically determine MIME types. this package is notoriously difficult to install, especially on win32 and OS X — like, genuinely a struggle. 😭 for OS X the easiest path might be to install Fink, then use apt-get install shared-mime-info. restart the server, and everything should be fine.

make sure you're using the latest version (>= 0.16) for best results. if you're having errors serving CSS files, or if they get served as text/plain instead of text/css, you may have an outdated shared-mime-info version. you may also wish to simply use the following code in your Static controller:

if ($c->req->path =~ /css$/i) {
    $c->serve_static( "text/css" );
} else {
    $c->serve_static;
}

🔥 Serving Static Files with Apache 🔥

when using Apache, you can bypass Catalyst and any Static plugins/controllers by intercepting requests for the root/static path at the server level. all that's required is to define a DocumentRoot and add a separate Location block for your static content. here's a complete config for this application under mod_perl 1.x:

<Perl>
    use lib qw(/var/www/MyApp/lib);
</Perl>
PerlModule MyApp

<VirtualHost *>
    ServerName myapp.example.com
    DocumentRoot /var/www/MyApp/root
    <Location />
        SetHandler perl-script
        PerlHandler MyApp
    </Location>
    <LocationMatch "/(static|favicon.ico)">
        SetHandler default-handler
    </LocationMatch>
</VirtualHost>

and here's a simpler example that'll get you started:

Alias /static/ "/my/static/files/"
<Location "/static">
    SetHandler none
</Location>

💜 Caching 💜

Catalyst makes it easy to employ several different types of caching to speed up your applications. we love a fast app. ⚡

🔥 Cache Plugins 🔥

there are three wrapper plugins around common CPAN cache modules: Cache::FastMmap, Cache::FileCache, and Cache::Memcached. these can be used to cache the result of slow operations. obsessed.

the Catalyst Advent Calendar uses the FileCache plugin to cache the rendered XHTML version of the source POD document. this is an ideal application for a cache because the source document changes infrequently but may be viewed many times. perfect match, honestly. 💖

use Catalyst qw/Cache::FileCache/;

...

use File::stat;
sub render_pod : Local {
    my ( self, $c ) = @_;

    # the cache is keyed on the filename and the modification time
    # to check for updates to the file.
    my $file  = $c->path_to( 'root', '2005', '11.pod' );
    my $mtime = ( stat $file )->mtime;

    my $cached_pod = $c->cache->get("$file $mtime");
    if ( !$cached_pod ) {
        $cached_pod = do_slow_pod_rendering();
        # cache the result for 12 hours
        $c->cache->set( "$file $mtime", $cached_pod, '12h' );
    }
    $c->stash->{pod} = $cached_pod;
}

we could actually cache the result forever, but using a value such as 12 hours lets old entries automatically expire when they're no longer needed. very demure, very mindful. ✨

🎀 Page Caching 🎀

Another caching glow-up is to cache the entire HTML page fr — like, the whole thing. Traditionally that's a frontend proxy server's job (hi Squid 👋), but the Catalyst::PageCache plugin makes it stupid easy to cache the whole output of actions that are either super popular or super slow.

Lots of sites have a busy, content-packed front page that looks kinda like this. It probably takes a hot minute to process, and it does the exact same thing for every single user who rolls through. 💀

sub front_page : Path('/') {
    my ( $self, $c ) = @_;

    $c->forward( 'get_news_articles' );
    $c->forward( 'build_lots_of_boxes' );
    $c->forward( 'more_slow_stuff' );

    $c->stash->{template} = 'index.tt';
}

So we add the PageCache plugin and boom, speed. ⚡

use Catalyst qw/Cache::FileCache PageCache/;

sub front_page : Path ('/') {
    my ( $self, $c ) = @_;

    $c->cache_page( 300 );

    # same processing as above
}

Now the entire output of the front page, from <html> all the way to </html>, gets cached for 5 minutes. After those 5 minutes, the next request rebuilds the page and it gets re-cached. Fresh-ish and fast, the dream combo. ✨

Heads up bestie: the page cache is keyed on the page URI plus all parameters, so requests for / and /?foo=bar will land in different cache items. Also, only GET requests get cached by the plugin. No cap.

And you can even get that frontend Squid proxy in on the action by turning on HTTP headers for the cached page:

MyApp->config(
    page_cache => {
        set_http_headers => 1,
    },
);

This would then set the following headers so proxies and browsers can cache the content themselves:

Cache-Control: max-age=($expire_time - time)
Expires: $expire_time
Last-Modified: $cache_created_time

---

🎀 Template Caching 🎀

Template Toolkit literally supports caching compiled versions of your templates. To enable it in Catalyst, use this config. TT keys the compiled templates on the file mtime, so changes still get detected automatically — iconic behaviour, honestly. 💅

package MyApp::View::TT;

use strict;
use warnings;
use base 'Catalyst::View::TT';

__PACKAGE__->config(
    COMPILE_DIR => '/tmp/template_cache',
);

1;

🌈 More Info 🌈

Peep the docs for each cache plugin for more deets and other config options you can play with:

• Catalyst::Plugin::Cache::FastMmap
• Catalyst::Plugin::Cache::FileCache
• Catalyst::Plugin::Cache::Memcached
• Catalyst::Plugin::PageCache
• "Caching and Compiling Options" in Template::Manual::Config

---

🧪 TESTING 🧪

Testing is an absolutely integral part of the web app dev process, fr fr. Tests make multi-developer teams way easier to coordinate, and they help make sure there are no nasty surprises after upgrades or alterations. No surprises is the whole vibe.

Testing

Catalyst gives you a convenient way to test your app during development and before deployment in a real environment.

Catalyst::Test makes it possible to run the same tests both locally (no external daemon needed, cute) and against a remote server via HTTP.

🦋 Tests 🦋

Let's examine a skeleton application's t/ directory:

mundus:~/MyApp chansen$ ls -l t/
total 24
-rw-r--r--  1 chansen  chansen   95 18 Dec 20:50 01app.t
-rw-r--r--  1 chansen  chansen  190 18 Dec 20:50 02pod.t
-rw-r--r--  1 chansen  chansen  213 18 Dec 20:50 03podcoverage.t

• 01app.t — verifies that the application loads, compiles, and returns a successful response.
• 02pod.t — verifies that all POD is free from errors. Only executed if the TEST_POD environment variable is true.
• 03podcoverage.t — verifies that all methods/functions have POD coverage. Only executed if the TEST_POD environment variable is true.

🌸 Creating tests 🌸

mundus:~/MyApp chansen$ cat t/01app.t | perl -ne 'printf( "%2d  %s", $., $_ )'
1  use Test::More tests => 2;
2  BEGIN { use_ok( Catalyst::Test, 'MyApp' ) }
3
4  ok( request('/')->is_success );

Line one declares how many tests we're running — in this case, two. Line two tests and loads our app in test mode. Line four verifies that our app returns a successful response. Slay. ✅

Catalyst::Test exports two functions, request and get. Each one can take three different arguments:

• A string which is a relative or absolute URI.

request('/my/path');
request('http://www.host.com/my/path');

• An instance of URI.

request( URI->new('http://www.host.com/my/path') );

• An instance of HTTP::Request.

request( HTTP::Request->new( GET => 'http://www.host.com/my/path') );

request returns an instance of HTTP::Response, and get returns the content (body) of the response. Two different flavours of the same energy. 🫶

💜 Running tests locally 💜

mundus:~/MyApp chansen$ CATALYST_DEBUG=0 TEST_POD=1 prove --lib lib/ t/
t/01app............ok
t/02pod............ok
t/03podcoverage....ok
All tests successful.
Files=3, Tests=4,  2 wallclock secs ( 1.60 cusr +  0.36 csys =  1.96 CPU)

• CATALYST_DEBUG=0 makes sure debugging is off; if it's enabled you'll see debug logs wedged between your tests (messy, not cute).
• TEST_POD=1 enables POD checking and coverage.
• prove — a command-line tool that makes running tests easy. You can find out more about it from the links below.

🧚 Running tests remotely 🧚

mundus:~/MyApp chansen$ CATALYST_SERVER=http://localhost:3000/ prove --lib lib/ t/01app.t
t/01app....ok
All tests successful.
Files=1, Tests=2,  0 wallclock secs ( 0.40 cusr +  0.01 csys =  0.41 CPU)

CATALYST_SERVER=http://localhost:3000/ is the absolute deployment URI of your app. In CGI or FastCGI it should be the host and path to the script.

🍓 Test::WWW::Mechanize and Catalyst 🍓

Definitely go check out Test::WWW::Mechanize::Catalyst. It makes testing HTML, forms and links genuinely easy. Short lil example of usage:

use Test::More tests => 6;
BEGIN { use_ok( Test::WWW::Mechanize::Catalyst, 'MyApp' ) }

my $mech = Test::WWW::Mechanize::Catalyst->new;
$mech->get_ok("http://localhost/", 'Got index page');
$mech->title_like( qr/^MyApp on Catalyst/, 'Got right index title' );
ok( $mech->find_link( text_regex => qr/^Wiki/i ), 'Found link to Wiki' );
ok( $mech->find_link( text_regex => qr/^Mailing-List/i ), 'Found link to Mailing-List' );
ok( $mech->find_link( text_regex => qr/^IRC channel/i ), 'Found link to IRC channel' );

⭐ Further Reading ⭐

• Catalyst::Test
• Test::WWW::Mechanize::Catalyst
• Test::WWW::Mechanize
• WWW::Mechanize
• LWP::UserAgent
• HTML::Form
• HTTP::Message
• HTTP::Request
• HTTP::Request::Common
• HTTP::Response
• HTTP::Status
• URI
• Test::More
• Test::Pod
• Test::Pod::Coverage
• prove (Test::Harness)

👑 More Information 👑

• Catalyst::Plugin::Authorization::Roles
• Catalyst::Plugin::Authorization::ACL

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💖 AUTHORS 💖

Catalyst Contributors, see Catalyst.pm. Shoutout to the whole crew, absolute legends, iykyk.

📜 COPYRIGHT 📜

This library is free software. You can redistribute it and/or modify it under the same terms as Perl itself. Free software bestie, go wild (within the terms 💅).

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That's a wrap on the whole cookbook, bestie!! 🎀✨ This edition is perl v5.42.0, dated 2024-03-23 — canonically the Catalys...ookbook(3) manpage, and now it lives rent-free in your brain. Go build something iconic. 🦋💜