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.
sub end : Private {
my ( $self, $c ) = @_;
die "forced debug";
}If you're tired of removing and adding this all the time, you can add a condition in the end action. For example:
sub end : Private {
my ( $self, $c ) = @_;
die "forced debug" if $c->req->params->{dump_info};
} Then just add to your query string "&dump_info=1", or the like, to force debug output.
Disable statistics
Just add this line to your application class if you don't want those nifty statistics in your debug messages.
sub Catalyst::Log::info { }Scaffolding
Scaffolding is very simple with Catalyst.
The recommended way is to use Catalyst::Helper::Controller::Scaffold.
Just install this module, and to scaffold a Class::DBI Model class, do the following:
./script/myapp_create controller <name> Scaffold <CDBI::Class>Scaffolding
File uploads
Single file upload with Catalyst
To implement uploads in Catalyst, you need to have a HTML form similar to this:
<form action="/upload" method="post" enctype="multipart/form-data">
<input type="hidden" name="form_submit" value="yes">
<input type="file" name="my_file">
<input type="submit" value="Send">
</form>It's very important not to forget enctype="multipart/form-data" in the form.
Catalyst Controller module 'upload' action:
sub upload : Global {
my ($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';
}for my $field ($c->req-upload)> loops automatically over all file input fields and gets input names. After that is basic file saving code, just like in single file upload.
Notice: dieing might not be what you want to do, when an error occurs, but it works as an example. A better idea would be to store error $! in $c->stash->{error} and show a custom error template displaying this message.
For more information about uploads and usable methods look at Catalyst::Request::Upload and Catalyst::Request.
Authentication with Catalyst::Plugin::Authentication
In this example, we'll use the Catalyst::Plugin::Authentication::Store::DBIC store and the Catalyst::Plugin::Authentication::Credential::Password credentials.
In the lib/MyApp.pm package, we'll need to change the use Catalyst; line to include the following modules:
use Catalyst qw/
ConfigLoader
Authentication
Authentication::Store::DBIC
Authentication::Credential::Password
Session
Session::Store::FastMmap
Session::State::Cookie
HTML::Widget
Static::Simple
/;The Session, Session::Store::* and Session::State::* modules listed above ensure that we stay logged-in across multiple page-views.
In our MyApp.yml configuration file, we'll need to add:
authentication:
dbic:
user_class: MyApp::Model::DBIC::User
user_field: username
password_field: password
password_type: hashed
password_hash_type: SHA-1'user_class' is a DBIx::Class package for your users table. 'user_field' tells which field (column) is used for username lookup. 'password_field' is the password field in your table. The above settings for 'password_type' and 'password_hash_type' ensure that the password won't be stored in the database in clear text.
In SQLite, the users table might be something like:
CREATE TABLE user (
id INTEGER PRIMARY KEY,
username VARCHAR(100),
password VARCHAR(100)
);Now we need to create a DBIC::SchemaLoader component for this database (changing "myapp.db" to wherever your SQLite database is).
script/myapp_create.pl model DBIC DBIC::SchemaLoader 'dbi:SQLite:myapp.db'Now we can start creating our page controllers and templates. For our homepage, we create the file "root/index.tt" containing:
<html>
<body>
[% IF c.user %]
<p>hello [% c.user.username %]</p>
<p><a href="[% c.uri_for( '/logout' ) %]">logout</a></p>
[% ELSE %]
<p><a href="[% c.uri_for( '/login' ) %]">login</a></p>
[% END %]
</body>
</html>If the user is logged in, they will be shown their name, and a logout link. Otherwise, they will be shown a login link.
To display the homepage, we can uncomment the default and end subroutines in lib/MyApp/Controller/Root.pm and populate them as so:
sub default : Private {
my ( $self, $c ) = @_;
$c->stash->{template} = 'index.tt';
}
sub end : Private {
my ( $self, $c ) = @_;
$c->forward( $c->view('TT') )
unless $c->response->body || $c->response->redirect;
}The login template is very simple, as HTML::Widget will handle the HTML form creation for use. This is saved as "root/login.tt".
<html>
<head>
<link href="[% c.uri_for('/static/simple.css') %]" rel="stylesheet" type="text/css">
</head>
<body>
[% result %]
</body>
</html>For the HTML form to look correct, we also copy the simple.css file from the HTML::Widget distribution into our "root/static" folder. This file is automatically server by the Catalyst::Plugin::Static::Simple module which we loaded in our lib/MyApp.pm package.
To handle login requests, we first create a controller, like so:
script/myapp_create.pl controller LoginIn the lib/MyApp/Controller/Login.pm package, we can then uncomment the default subroutine, and populate it, as below.
First the widget is created, it needs the 'action' set, and 'username' and 'password' fields and a submit button added.
Then, if we've received a username and password in the request, we attempt to login. If successful, we redirect to the homepage; if not the login form will be displayed again.
sub default : Private {
my ( $self, $c ) = @_;
$c->widget->method('POST')->action( $c->uri_for('/login') );
$c->widget->element( 'Textfield', 'username' )->label( 'Username' );
$c->widget->element( 'Password', 'password' )->label( 'Password' );
$c->widget->element( 'Submit' )->value( 'Login' );
my $result = $c->widget->process( $c->req );
if ( my $user = $result->param('username')
and my $pass = $result->param('password') )
{
if ( $c->login( $user, $pass ) ) {
$c->response->redirect( $c->uri_for( "/" ) );
return;
}
}
$c->stash->{template} = 'login.tt';
$c->stash->{result} = $result;
}To handle logout's, we create a new controller:
script/myapp_create.pl controller LogoutThen in the lib/MyApp/Controller/Logout.pm package, we change the default subroutine, to logout and then redirect back to the homepage.
sub default : Private {
my ( $self, $c ) = @_;
$c->logout;
$c->response->redirect( $c->uri_for( "/" ) );
}Remember that to test this, we would first need to add a user to the database, ensuring that the password field is saved as the SHA1 hash of our desired password.
Pass-through login (and other actions)
An easy way of having assorted actions that occur during the processing of a request that are orthogonal to its actual purpose - logins, silent commands etc. Provide actions for these, but when they're required for something else fill e.g. a form variable __login and have a sub begin like so:
sub begin : Private {
my ($self, $c) = @_;
foreach my $action (qw/login docommand foo bar whatever/) {
if ($c->req->params->{"__${action}"}) {
$c->forward($action);
}
}
}How to use Catalyst without mod_perl
Catalyst applications give optimum performance when run under mod_perl. However sometimes mod_perl is not an option, and running under CGI is just too slow. There's also an alternative to mod_perl that gives reasonable performance named FastCGI.
Using FastCGI
To quote from http://www.fastcgi.com/: "FastCGI is a language independent, scalable, extension to CGI that provides high performance without the limitations of specific server APIs." Web server support is provided for Apache in the form of mod_fastcgi and there is Perl support in the FCGI module. To convert a CGI Catalyst application to FastCGI one needs to initialize an FCGI::Request object and loop while the Accept method returns zero. The following code shows how it is done - and it also works as a normal, single-shot CGI script.
#!/usr/bin/perl
use strict;
use FCGI;
use MyApp;
my $request = FCGI::Request();
while ($request->Accept() >= 0) {
MyApp->run;
}Any initialization code should be included outside the request-accept loop.
There is one little complication, which is that MyApp->run outputs a complete HTTP response including the status line (e.g.: "HTTP/1.1 200"). FastCGI just wants a set of headers, so the sample code captures the output and drops the first line if it is an HTTP status line (note: this may change).
The Apache mod_fastcgi module is provided by a number of Linux distro's and is straightforward to compile for most Unix-like systems. The module provides a FastCGI Process Manager, which manages FastCGI scripts. You configure your script as a FastCGI script with the following Apache configuration directives:
<Location /fcgi-bin>
AddHandler fastcgi-script fcgi
</Location>or:
<Location /fcgi-bin>
SetHandler fastcgi-script
Action fastcgi-script /path/to/fcgi-bin/fcgi-script
</Location>mod_fastcgi provides a number of options for controlling the FastCGI scripts spawned; it also allows scripts to be run to handle the authentication, authorization, and access check phases.
For more information see the FastCGI documentation, the FCGI module and http://www.fastcgi.com/.
Serving static content
Serving static content in Catalyst can be somewhat tricky; this recipe shows one possible solution. Using this recipe will serve all static content through Catalyst when developing with the built-in HTTP::Daemon server, and will make it easy to use Apache to serve the content when your app goes into production.
Static content is best served from a single directory within your root directory. Having many different directories such as root/css and root/images requires more code to manage, because you must separately identify each static directory--if you decide to add a root/js directory, you'll need to change your code to account for it. In contrast, keeping all static directories as subdirectories of a main root/static directory makes things much easier to manager. Here's an example of a typical root directory structure:
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.jsAll static content lives under root/static with everything else being Template Toolkit files. Now you can identify the static content by matching static from within Catalyst.
Serving with HTTP::Daemon (myapp_server.pl)
To serve these files under the standalone server, we first must load the Static plugin. Install Catalyst::Plugin::Static if it's not already installed.
In your main application class (MyApp.pm), load the plugin:
use Catalyst qw/-Debug FormValidator Static OtherPlugin/;You will also need to make sure your end method does not forward static content to the view, perhaps like this:
sub end : Private {
my ( $self, $c ) = @_;
$c->forward( 'MyApp::V::TT' )
unless ( $c->res->body || !$c->stash->{template} );
}This code will only forward to the view if a template has been previously defined by a controller and if there is not already data in $c->res->body.
Next, create a controller to handle requests for the /static path. Use the Helper to save time. This command will create a stub controller as lib/MyApp/C/Static.pm.
$ script/myapp_create.pl controller StaticEdit 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 ) = @_;
$c->serve_static;
}You can also define a different icon for the browser to use instead of favicon.ico by using this in your HTML header:
<link rel="icon" href="/static/myapp.ico" type="image/x-icon" />Common problems
The Static plugin makes use of the shared-mime-info package to automatically determine MIME types. This package is notoriously difficult to install, especially on win32 and OS X. For OS X the easiest path might be to install Fink, then use apt-get install shared-mime-info. Restart the server, and everything should be fine.
Make sure you are using the latest version (>= 0.16) for best results. If you are having errors serving CSS files, or if they get served as text/plain instead of text/css, you may have an outdated shared-mime-info version. You may also wish to simply use the following code in your Static controller:
if ($c->req->path =~ /css$/i) {
$c->serve_static( "text/css" );
} else {
$c->serve_static;
}Serving with Apache
When using Apache, you can completely bypass Catalyst and the Static controller by intercepting requests for the root/static path at the server level. All that is required is to define a DocumentRoot and add a separate Location block for your static content. Here is 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>Forwarding with arguments
Sometimes you want to pass along arguments when forwarding to another action. As of version 5.30, arguments can be passed in the call to forward; in earlier versions, you can manually set the arguments in the Catalyst Request object:
# 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 information on passing arguments via forward.)
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 YAML
YAML 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.
In your application class (e.g. lib/MyApp.pm):
use YAML;
# application setup
__PACKAGE__->config( YAML::LoadFile(__PACKAGE__->config->{'home'} . '/myapp.yml') );
__PACKAGE__->setup;Now create myapp.yml in your application home:
--- #YAML:1.0
# DO NOT USE TABS FOR INDENTATION OR label/value SEPARATION!!!
name: MyApp
# session; perldoc Catalyst::Plugin::Session::FastMmap
session:
expires: '3600'
rewrite: '0'
storage: '/tmp/myapp.session'
# emails; perldoc Catalyst::Plugin::Email
# this passes options as an array :(
email:
- SMTP
- localhostThis is equivalent to:
# configure base package
__PACKAGE__->config( name => MyApp );
# configure authentication
__PACKAGE__->config->{authentication} = {
user_class => 'MyApp::M::MyDB::Customer',
...
};
# configure sessions
__PACKAGE__->config->{session} = {
expires => 3600,
...
};
# configure email sending
__PACKAGE__->config->{email} = [qw/SMTP localhost/];See also YAML.
Using existing DBIC (etc.) classes with Catalyst
Many people have existing Model classes that they would like to use with Catalyst (or, conversely, they want to write Catalyst models that can be used outside of Catalyst, e.g. in a cron job). 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! Now Some::DBIC::Schema is part of your Cat app as MyApp::Model::DB.
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 a full Data::Dumper output 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;
$c->stash->{template} = 'errors.tt';
$c->forward('MyApp::View::TT');
$c->error(0);
}
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
$c->error( 'You broke me!' );Require user logins
It's often useful to restrict access to your application to a set of registered users, forcing everyone else to the login page until they're signed in.
To implement this in your application make sure you have a customer table with username and password fields and a corresponding Model class in your Catalyst application, then make the following changes:
lib/MyApp.pm
use Catalyst qw/
Authentication
Authentication::Store::DBIC
Authentication::Credential::Password
/;
__PACKAGE__->config->{authentication}->{dbic} = {
'user_class' => 'My::Model::DBIC::User',
'user_field' => 'username',
'password_field' => 'password'
'password_type' => 'hashed',
'password_hash_type'=> 'SHA-1'
};
sub auto : Private {
my ($self, $c) = @_;
my $login_path = 'user/login';
# allow people to actually reach the login page!
if ($c->request->path eq $login_path) {
return 1;
}
# if a user doesn't exist, force login
if ( !$c->user_exists ) {
# force the login screen to be shown
$c->response->redirect($c->request->base . $login_path);
}
# otherwise, we have a user - continue with the processing chain
return 1;
}lib/MyApp/C/User.pm
sub login : Path('/user/login') {
my ($self, $c) = @_;
# default template
$c->stash->{'template'} = "user/login.tt";
# default form message
$c->stash->{'message'} = 'Please enter your username and password';
if ( $c->request->param('username') ) {
# try to log the user in
# login() is provided by ::Authentication::Credential::Password
if( $c->login(
$c->request->param('username'),
$c->request->param('password'),
);
# if login() returns 1, user is now logged in
$c->response->redirect('/some/page');
}
# otherwise we failed to login, try again!
$c->stash->{'message'} =
'Unable to authenticate the login details supplied';
}
}
sub logout : Path('/user/logout') {
my ($self, $c) = @_;
# log the user out
$c->logout;
# do the 'default' action
$c->response->redirect($c->request->base);
}root/base/user/login.tt
[% INCLUDE header.tt %]
<form action="/user/login" method="POST" name="login_form">
[% message %]<br />
<label for="username">username:</label><br />
<input type="text" id="username" name="username" /><br />
<label for="password">password:</label><br />
<input type="password" id="password" name="password" /><br />
<input type="submit" value="log in" name="form_submit" />
</form>
[% INCLUDE footer.tt %]Role-based Authorization
For more advanced access control, you may want to consider using role-based authorization. This means you can assign different roles to each user, e.g. "user", "admin", etc.
The login and logout methods and view template are exactly the same as in the previous example.
The Catalyst::Plugin::Authorization::Roles plugin is required when implementing roles:
use Catalyst qw/
Authentication
Authentication::Credential::Password
Authentication::Store::Htpasswd
Authorization::Roles
/;Roles are implemented automatically when using Catalyst::Authentication::Store::Htpasswd:
# no additional role configuration required
__PACKAGE__->config->{authentication}{htpasswd} = "passwdfile";Or can be set up manually when using Catalyst::Authentication::Store::DBIC:
# Authorization using a many-to-many role relationship
__PACKAGE__->config->{authorization}{dbic} = {
'role_class' => 'My::Model::DBIC::Role',
'role_field' => 'name',
'user_role_user_field' => 'user',
# DBIx::Class only (omit if using Class::DBI)
'role_rel' => 'user_role',
# Class::DBI only, (omit if using DBIx::Class)
'user_role_class' => 'My::Model::CDBI::UserRole'
'user_role_role_field' => 'role',
};To restrict access to any action, you can use the check_user_roles method:
sub restricted : Local {
my ( $self, $c ) = @_;
$c->detach("unauthorized")
unless $c->check_user_roles( "admin" );
# do something restricted here
}You can also use the assert_user_roles method. This just gives an error if the current user does not have one of the required roles:
sub also_restricted : Global {
my ( $self, $c ) = @_;
$c->assert_user_roles( qw/ user admin / );
}AUTHOR
Sebastian Riedel, sri@oook.de Danijel Milicevic, me@danijel.de Viljo Marrandi, vilts@yahoo.com Marcus Ramberg, mramberg@cpan.org Jesse Sheidlower, jester@panix.com Andy Grundman, andy@hybridized.org Chisel Wright, pause@herlpacker.co.uk Will Hawes, info@whawes.co.uk Gavin Henry, ghenry@cpan.org (Spell checking)
COPYRIGHT
This program is free software, you can redistribute it and/or modify it under the same terms as Perl itself.