NAME

Catalyst::Manual::Cookbook - Cooking with Catalyst

DESCRIPTION

Yummy code like your mum used to bake!

RECIPES

Force debug screen

You can force Catalyst to display the debug screen at the end of the request by placing a die() call in the _end action.

__PACKAGE__->action(
    '!end' => sub {
        my ( $self, $c ) = @_;
        die "testing";
    }
);

If you're tired of removing and adding this all the time, you can easily add a condition. for example:

die "Testing" if $c->param->{dump_info};

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 { }

Scaffolding

Scaffolding is very simple with Catalyst. Just use Catalyst::Model::CDBI::CRUD as baseclass.

# lib/MyApp/Model/CDBI.pm
package MyApp::Model::CDBI;

use strict;
use base 'Catalyst::Model::CDBI::CRUD';

__PACKAGE__->config(
    dsn           => 'dbi:SQLite:/tmp/myapp.db',
    relationships => 1
);

1;

# lib/MyApp.pm
package MyApp;

use Catalyst 'FormValidator';

__PACKAGE__->config(
    name => 'My Application',
    root => '/home/joeuser/myapp/root'
);

__PACKAGE__->action(
    'table' => sub {
        my ( $self, $c ) = @_;
        $c->form( optional => [ MyApp::Model::CDBI::Table->columns ] );
        $c->forward('MyApp::Model::CDBI::Table');
    }
);

1;

Modify the $c->form() parameters to match your needs, and don't forget to copy the templates. ;)

Serving static files and CSS as text/css

If you want to serve static content (like images, txt or CSS) via Catalyst, then all you need is the plugin Catalyst::Plugin::Static as well as a small regex to set the MIME type for CSS to text/css.

    # lib/MyApp.pm
    package MyApp;

    use strict;
    use Catalyst qw/-Debug Static/;
    
    __PACKAGE__->action(

        '!default' => sub {
            my ( $self, $c ) = @_;
	    $c->serve_static;
	},
	    
        '/^.*\.css$/' => sub {
            my ( $self, $c ) = @_;
            $c->serve_static('text/css');
        },
    );

Uploads with Catalyst

To implement uploads in Catalyst you need to have a HTML form similiar 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 form, if it's not there, uploads just don't work.

Catalyst Controller module 'upload' action:

MyApp->action(

    'upload' => sub {
        my ($self, $c) = @_;
        if ($c->req->parameters->{form_submit} eq 'yes') {
            my $filename = $c->req->parameters->{my_file};
            if ($filename) {
                my $fh = $c->req->uploads->{$filename}->{fh};
                open(NEW_FILE, ">/tmp/$filename") or die
                    "Can't open file for writing: $!";
                while ($fh->read(my $buf, 32768)) {
                    print NEW_FILE $buf;
                }
                close(NEW_FILE);
            }
        }
        $c->stash->{template} = 'upload_form.tt';
        $c->forward('MyApp::V::View');
    },
);

If you want to upload bigger files than 1MB, then just add to your Controller module:

$CGI::Simple::POST_MAX = 1048576000;

Authentication with Catalyst::Plugin::Authentication::CDBI

There are (at least) two ways to implement authentication with this plugin: 1) only checking username and password 2) checking username, password and the roles the user has

For both variants you'll need the following code in your MyApp package:

use Catalyst qw/Session::FastMmap Static Authentication::CDBI/;

MyApp->config( authentication => { user_class => 'MyApp::M::MyApp::Users',
                                   user_field => 'email',
                                   password_field => 'password' });

'user_class' is a Class::DBI class for your users table. 'user_field' tells which field is used for username lookup (might be email, first name, surname etc). 'password_field' is, well, password field in your table and by default password is stored in plain text. Authentication::CDBI looks for 'user' and 'password' fields in table, if they're not defined in the config.

In PostgreSQL users table might be something like:

CREATE TABLE users ( user_id serial, name varchar(100), surname varchar(100), password varchar(100), email varchar(100), primary key(user_id) );

We'll discuss the first variant for now: 1. user:password login / auth without roles

To log in a user you might use a action like this:

    '?login' => sub {
        my ($self, $c) = @_;
        if ($c->req->params->{username}) {
            $c->session_login($c->req->params->{username}, 
	                      $c->req->params->{password} );
            if ($c->req->{user}) {
                $c->forward('?restricted_area');
            }
        }
    },

$c->req->params->{username} and $c->req->params->{password} are html form parameters from a login form. If login succeeds, then $c->req->{user} contains the username of the authenticated user.

If you want to remember the users login status inbetween further requests, then just use the $c->session_login method, Catalyst will create a session id, session cookie and automatically append session id to all urls. So all you have to do, is just check $c->req->{user} where needed.

To log out user, just call $c->session_logout.

Now lets take a look at the second variant: 2. user:password login / auth with roles

To use roles you need to add to MyApp->config in the 'authentication' section following parameters:

role_class      => 'MyApp::M::MyApp::Roles',
user_role_class => 'MyApp::M::MyApp::UserRoles',
user_role_user_field => 'user_id',
user_role_role_field => 'role_id',

Corresponding tables in PostgreSQL could look like this:

CREATE TABLE roles ( role_id serial, name varchar(100), primary key(role_id) );

CREATE TABLE user_roles ( user_role_id serial, user_id int, role_id int, primary key(user_role_id), foreign key(user_id) references users(user_id), foreign key(role_id) references roles(role_id) );

The 'roles' table is a list of role names and the 'user_role' table is used for the user -> role lookup.

Now if a logged in user wants to see a location which is allowed only for people with 'admin' role then in you controller you can check it with:

'?add' => sub {
    my ($self, $c) = @_;
    if ($c->roles(qw/admin/)) {
        $c->req->output("Your account has the role 'admin.'");
    } else {
        $c->req->output("You're not allowed to be here");
    }
},

One thing you might need is to forward non-authenticated users to login form, if they try to access restricted areas. If you want to do this controller-wide (if you have one controller for admin section) then it's best to add user check to '!begin' action:

'!begin' => sub {
    my ($self, $c) = @_;
    unless ($c->req->{user}) {
        $c->req->action(undef);  ## notice this!!
        $c->forward('?login');
    }
},

Pay attention to $c->req->action(undef). This is needed, because of the way $c->forward works - forward to login gets called, but after that Catalyst executes anyway the action defined in the uri (eg. if you tried to watch /add, then first '!begin' forwards to '?login', but after that anyway '?add' is executed). So $c->req->action(undef) undefines any actions that were to be called and forwards user where we want him/her to be.

And this is all you need to do, isn't Catalyst wonderful?

AUTHOR

Sebastian Riedel, sri@oook.de Danijel Milicevic me@danijel.de Viljo Marrandi vilts@yahoo.com

COPYRIGHT

This program is free software, you can redistribute it and/or modify it under the same terms as Perl itself.

cpanm Catalyst

perl -MCPAN -e shell
install Catalyst