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[catagits/Catalyst-Runtime.git] / lib / Catalyst / Manual / Cookbook.pod

=head1 NAME

Catalyst::Manual::Cookbook - Cooking with Catalyst

=head1 DESCRIPTION

Yummy code like your mum used to bake!

=head1 RECIPES

=head2 Force debug screen

You can force Catalyst to display the debug screen at the end of the request by
placing a C<die()> call in the C<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 C<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 C<"&dump_info=1">, or the like, to
force debug output.


=head2 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 { }

=head2 Scaffolding

Scaffolding is very simple with Catalyst.
Just use Catalyst::Model::CDBI::CRUD as your base class.

    # 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'
    );

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

    1;

Modify the C<$c-E<gt>form()> parameters to match your needs, and don't
forget to copy the templates into the template root. Can't find the
templates?  They were in the CRUD model distribution, so you can do
B<look Catalyst::Model::CDBI::CRUD> from the CPAN shell to find them.

Other Scaffolding modules are in development at the time of writing.

=head2 File uploads

=head3 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 C<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';
    }

=head3 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';
    }

C<for my $field ($c-E<gt>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: C<die>ing 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 C<$!> in $c->stash->{error} and show a custom error template
displaying this message.

For more information about uploads and usable methods look at
L<Catalyst::Request::Upload> and L<Catalyst::Request>.

=head2 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, the 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 an action like this:

    sub login : Local {
        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');
            }
        }
    }

This action should not go in your MyApp class...if it does, it will
conflict with the built-in method of the same name.  Instead, put it
in a Controller class.

$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 user's login status in between further 
requests, then just use the C<$c-E<gt>session_login> method. Catalyst will 
create a session id and 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 a user, just call $c->session_logout.

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

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

    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 an 'admin' role, in your controller you can check it 
with:

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

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

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

Pay attention to $c->req->action(undef). This is needed because of the
way $c->forward works - C<forward> to C<login> gets called, but after
that Catalyst will still execute the action defined in the URI (e.g. if
you tried to go to C</add>, then first 'begin' will forward to 'login',
but after that 'add' will nonetheless be executed). So
$c->req->action(undef) undefines any actions that were to be called and
forwards the user where we want him/her to be.

And this is all you need to do. 

=head2 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);
        }
      }
    }

=head2 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.

=head3 Using FastCGI

To quote from L<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 C<mod_fastcgi> and there is Perl
support in the C<FCGI> module.  To convert a CGI Catalyst application 
to FastCGI one needs to initialize an C<FCGI::Request> object and loop 
while the C<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 C<MyApp-E<gt>run> outputs a
complete HTTP response including the status line (e.g.: 
"C<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 C<mod_fastcgi> module is provided by a number of Linux 
distros 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>

C<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 C<FCGI> module 
and L<http://www.fastcgi.com/>.
 
=head2 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 C<root/css> and
C<root/images> requires more code to manage, because you must separately
identify each static directory--if you decide to add a C<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
C<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.js


All static content lives under C<root/static> with everything else being
Template Toolkit files. Now you can identify the static content by
matching C<static> from within Catalyst.

=head3 Serving with HTTP::Daemon (myapp_server.pl)

To serve these files under the standalone server, we first must load the
Static plugin. Install L<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 I<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<$c-E<gt>res-E<gt>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
C<lib/MyApp/C/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" />

=head3 Common problems

The Static plugin makes use of the C<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 C<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;
    }

=head3 Serving with Apache

When using Apache, you can completely bypass Catalyst and the Static
controller by intercepting requests for the C<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>

=head2 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
C<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 L<Catalyst::Manual::Intro#Flow_Control> for more information on
passing arguments via C<forward>.)

=head2 Configure your application

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

=head3 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. C<lib/MyApp.pm>):

  use YAML;
  # application setup
  __PACKAGE__->config( YAML::LoadFile(__PACKAGE__->config->{'home'} . '/myapp.yml') );
  __PACKAGE__->setup;

Now create C<myapp.yml> in your application home:

  --- #YAML:1.0
  # DO NOT USE TABS FOR INDENTATION OR label/value SEPARATION!!!
  name:     MyApp

  # authentication; perldoc Catalyst::Plugin::Authentication::CDBI
  authentication:
    user_class:           'MyApp::M::MyDB::Customer'
    user_field:           'username'
    password_field:       'password'
    password_hash:        'md5'
    role_class:           'MyApp::M::MyDB::Role'
    user_role_class:      'MyApp::M::MyDB::PersonRole'
    user_role_user_field: 'person'

  # 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
    - localhost

This 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 L<YAML>.

=head2 Using existing CDBI (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::M::Catalog;
    use base qw/Catalyst::Base Some::Other::CDBI::Module::Catalog/;
    1;

and that's it! Now C<Some::Other::CDBI::Module::Catalog> is part of your
Cat app as C<MyApp::M::Catalog>.

=head2 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 C<-Debug>
mode, the error page is a useful screen including the error message and
a full Data::Dumper output of the C<$c> context object. When not in
C<-Debug>, users see a simple "Please come back later" screen.

To use a custom error page, use a special C<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 C<fillform> will probably need to go into this
C<end> method; see L<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} = [];
        }
    
        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!' );

=head1 AUTHOR

Sebastian Riedel, C<sri@oook.de>
Danijel Milicevic, C<me@danijel.de>
Viljo Marrandi, C<vilts@yahoo.com>  
Marcus Ramberg, C<mramberg@cpan.org>
Jesse Sheidlower, C<jester@panix.com>
Andy Grundman, C<andy@hybridized.org> 
Chisel Wright, C<pause@herlpacker.co.uk>

=head1 COPYRIGHT

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