Name
Catalyst::View::TD - Catalyst Template::Declare View Class
Synopsis
Use the helper to create your view:
./script/myapp_create.pl view HTML TD
Create a template by editing lib/MyApp/Templates/HTML.pm:
template hello => sub {
my ($self, $vars) = @_;
html {
head { title { "Hello, $vars->{user}" } };
body { h1 { "Hello, $vars->{user}" } };
};
};
Render the view from MyApp::Controller::SomeController:
sub message : Global {
my ( $self, $c ) = @_;
$c->stash->{template} = 'hello';
$c->stash->{user} = 'Slim Shady';
$c->forward( $c->view('HTML') );
}
Description
This is the Catalyst view class for Template::Declare. Your application
should define a view class that subclasses this module. The easiest way
to achieve this is using the myapp_create.pl script (where myapp should
be replaced with whatever your application is called). This script is
created as part of the Catalyst setup.
./script/myapp_create.pl view HTML TD
This creates a "MyApp::View::HTML" module in the lib directory (again,
replacing "MyApp" with the name of your application) that looks
something like this:
package MyApp::View::HTML;
use strict;
use warnings;
use parent 'Catalyst::View::TD';
__PACKAGE__->config(
# dispatch_to => [qw(MyApp::Templates::HTML)],
# auto_alias => 1,
# strict => 1,
# postprocessor => sub { ... },
# around_template => sub { ... },
);
It also creates a "MyApp::Templates::HTML" template class that looks
something like this:
package MyApp::Templates::HTML;
use strict;
use warnings;
use parent 'Template::Declare::Catalyst';
use Template::Declare::Tags;
# template hello => sub {
# my ($self, $vars) = @_;
# html {
# head { title { "Hello, $vars->{user}" } };
# body { h1 { "Hello, $vars->{user}" } };
# };
# };
Now you can modify your action handlers in the main application and/or
controllers to forward to your view class. You might choose to do this
in the "end()" method, for example, to automatically forward all actions
to the TD view class.
# In MyApp::Controller::SomeController
sub end : Private {
my( $self, $c ) = @_;
$c->forward( $c->view('HTML') );
}
Configuration
There are a three different ways to configure your view class (see
config for an explanation of the configuration options). The first way
is to call the "config()" method in the view subclass. This happens when
the module is first loaded.
package MyApp::View::HTML;
use strict;
use parent 'Catalyst::View::TD';
__PACKAGE__->config({
dispatch_to => [ 'MyApp::Templates::HTML' ],
auto_alias => 1,
strict => 1,
postprocessor => sub { ... },
around_template => sub { ... },
});
The second way is to define a "new()" method in your view subclass. This
performs the configuration when the view object is created, shortly
after being loaded. Remember to delegate to the base class "new()"
method (via "$self->next::method()" in the example below) after
performing any configuration.
sub new {
my $self = shift;
$self->config({
dispatch_to => [ 'MyApp::Templates::HTML' ],
auto_alias => 1,
strict => 1,
postprocessor => sub { ... },
around_template => sub { ... },
});
return $self->next::method(@_);
}
The final, and perhaps most direct way, is to call the ubiquitous
"config()" method in your main application configuration. The items in
the class hash are added to those already defined by the above two
methods. This happens in the base class "new()" method (which is one
reason why you must remember to call it via "MRO::Compat" if you
redefine the "new()" method in a subclass).
package MyApp;
use strict;
use Catalyst;
MyApp->config({
name => 'MyApp',
'View::HTML' => {
dispatch_to => [ 'MyApp::Templates::HTML' ],
auto_alias => 1,
strict => 1,
postprocessor => sub { ... },
around_template => sub { ... },
},
});
Note that any configuration defined by one of the earlier methods will
be overwritten by items of the same name provided by the later methods.
Auto-Aliasing
In addition to the dispatch template class (as defined in the
"dispatch_to" configuration, or defaulting to
"MyApp::Templates::ViewName"), you can write templates in other classes
and they will automatically be aliased into the dispatch class. The
aliasing of templates is similar to how controller actions map to URLs.
For example, say that you have a dispatch template class for your
"MyApp::View::XHTML" view named "MyApp::Templates::XHTML":
package TestApp::Templates::XHTML;
use parent 'Template::Declare::Catalyst';
use Template::Declare::Tags;
template home => sub {
html {
head { title { 'Welcome home' } };
body { h1 { 'Welcome home' } };
};
};
This will handle a call to render the "/home" (or just "home"):
$c->stash->{template} = 'home';
$c->forward( $c->view('XHTML') );
But let's say that you have a controller, "MyApp::Controller::Users",
that has an action named "list". Ideally what you'd like to do is to
have it dispatch to a view named "/users/list". And sure enough, you can
define one right in the dispatch class if you like:
template 'users/list' => sub {
my ($self, $args) = @_;
ul {
li { $_ } for @{ $args->{users} };
};
};
But it can get to be a nightmare to manage *all* of your templates in
this one class. A better idea is to define them in multiple template
classes just as you have actions in multiple controllers. The
"auto_alias" feature of Catalyst::View::TD does just that. Rather than
define a template named "users/list" in the dispatch class
("MyApp::Templates::XHTML"), create a new template class,
"MyApp::Templates::XHTML::Users":
./script/myapp_create.pl TDClass XHTML::Users
Then create a "list" template there:
package TestApp::Templates::XHTML::Users;
use parent 'Template::Declare::Catalyst';
use Template::Declare::Tags;
template list => sub {
my ($self, $args) = @_;
ul { li { $_ } for @{ $args->{users} } };
};
Catalyst::View::TD will automatically import the templates found in all
classes defined below the dispatch class. Thus this template will be
imported as "users/list". The nice thing about this is it allows you to
create template classes with templates that correspond directly to
controller classes and their actions.
You can also use this approach to create utility templates. For example,
if you wanted to put the header and footer output into utility
templates, you could put them into a utility class:
package TestApp::Templates::XHTML::Util;
use parent 'Template::Declare::Catalyst';
use Template::Declare::Tags;
template header => sub {
my ($self, $args) = @_;
head { title { $args->{title} } };
};
template footer => sub {
div {
id is 'fineprint';
p { 'Site contents licensed under a Creative Commons License.' }
};
};
And then you can simply use these templates from the dispatch class or
any other aliased template class, including the dispatch class:
package TestApp::Templates::XHTML;
use parent 'Template::Declare::Catalyst';
use Template::Declare::Tags;
template home => sub {
html {
show '/util/header';
body {
h1 { 'Welcome home' };
show '/util/footer';
};
};
};
And the users class:
package TestApp::Templates::XHTML::Users;
use parent 'Template::Declare::Catalyst';
use Template::Declare::Tags;
template list => sub {
my ($self, $args) = @_;
html {
show '/util/header';
body {
ul { li { $_ } for @{ $args->{users} } };
show '/util/footer';
};
};
};
If you'd rather control the importing of templates yourself, you can
always set "auto_alias" to a false value. Then you'd just need to
explicitly inherit from "Template::Declare::Catayst" and do the mixing
yourself. The equivalent to the auto-aliasing in the above examples
would be:
package TestApp::Templates::XHTML;
use parent 'Template::Declare::Catalyst';
use Template::Declare::Tags;
use TestApp::Templates::XHTML::Users;
use TestApp::Templates::XHTML::Util;
alias TestApp::Templates::XHTML::Users under '/users';
alias TestApp::Templates::XHTML::Util under '/util';
This would be the way to go if you wanted finer control over
Template::Declare's composition features.
Dynamic "dispatch_to"
Sometimes it is desirable to modify "dispatch_to" for your templates at
runtime. Additional paths can be prepended or appended "dispatch_to" via
the stash as follows:
$c->stash->{prepend_template_classes} = [ 'MyApp::Other::Templates' ];
$c->stash->{append_template_classes} = [ 'MyApp::Fallback::Templates' ];
If you need to munge the list of dispatch classes in more complex ways,
there is also a "dispatch_to()" accessor:
my $view = $c->view('HTML')
splice @{ $view->dispatch_to }, 1, 0, 'My::Templates'
unless grep { $_ eq 'My::Templates' } $view->dispatch_to;
Note that if you use "dispatch_to()" to change template classes, they
are *permanently* changed. You therefore must check for duplicate paths
if you do this on a per-request basis, as in this example. Otherwise,
the class will continue to be added on every request, which would be a
rather ugly memory leak.
A safer approach is to use "dispatch_to()" to overwrite the array of
template classes rather than adding to it. This eliminates both the need
to perform duplicate checking and the chance of a memory leak:
$c->view('HTML')->dispatch_to( ['My::Templates', 'Your::Templates'] );
This is safe to do on a per-request basis. But you're really better off
using the stash approach. I suggest sticking to that when you can.
If you are calling "render" directly, then you can specify extra
template classes under the "prepend_template_classes" and
"append_template_classes" keys. See "Capturing Template Output" for an
example.
Rendering Views
The Catalyst "view()" method renders the template specified in the
"template" item in the stash.
sub message : Global {
my ( $self, $c ) = @_;
$c->stash->{template} = 'message';
$c->forward( $c->view('HTML') );
}
If a stash item isn't defined, then it instead uses the stringification
of the action dispatched to (as defined by "$c->action"). In the above
example, this would be "message".
The items defined in the stash are passed to the the Template::Declare
template as a hash reference. Thus, for this controller action:
sub default : Private {
my ( $self, $c ) = @_;
$c->stash->{template} = 'message';
$c->stash->{message} = 'Hello World!';
$c->forward( $c->view('TD') );
}
Your template can use access the "message" key like so:
template message => sub {
my ($self, $args) = @_;
h1 { $args->{message} };
};
Template classes are automatically subclasses of
Template::Declare::Catalyst, which is itself a subclass of
Template::Declare. Template::Declare::Catalyst provides a few extra
accessors for use in your templates (though note that they will return
"undef" if you call "render()" without a context object):
"context"
A reference to the context object, $c
"c" An alias for "context()"
These can be accessed from the template like so:
template message => sub {
my ($self, $args) = @_;
p { "The message is $args->{message}" };
p { "The base is " . $self->context->req->base };
p { "The name is " . $self->c->config->{name} };
};
The output generated by the template is stored in "$c->response->body".
Capturing Template Output
If you wish to use the output of a template for some purpose other than
displaying in the response, e.g. for sending an email, use
Catalyst::Plugin::Email and the render method:
sub send_email : Local {
my ($self, $c) = @_;
$c->email(
header => [
To => 'me@localhost',
Subject => 'A TD Email',
],
body => $c->view('TD')->render($c, 'email', {
prepend_template_classes => [ 'My::EmailTemplates' ],
email_tmpl_param1 => 'foo'
}),
);
# Redirect or display a message
}
Template Class Helper
In addition to the usual helper for creating TD views, you can also use
the "TDClass" helper to create new template classes:
./script/myapp_create.pl TDClass HTML::Users
This will create a new Template::Declare template class,
"MyApp::Templates::HTML::Users" in the lib directory. This is perhaps
best used in conjunction with creating a new controller for which you
expect to create views:
./script/myapp_create.pl controller Users
./script/myapp_create.pl TDClass HTML::Users
As explained in "Auto-Aliasing", if you already have the TD view
"MyApp::View::HTML", the templates in the
"MyApp::Templates::HTML::Users" class will be aliased under the "/users"
path. So if you defined a "list" action in the "Users" controller and a
corresponding "list" view in the "HTML::Users" view, both would resolve
to "/users/list".
Methods
Constructor
"new"
my $view = MyApp::View::HTML->new( $c, $args );
The constructor for the TD view. Sets up the template provider and reads
the application config. The $args hash reference, if present, overrides
the application config.
Class Methods
"config"
__PACKAGE__->config(
dispatch_to => [qw(MyApp::Templates::HTML)],
auto_alias => 1,
strict => 1,
postprocessor => sub { ... },
around_template => sub { ... },
);
Sets up the configuration your view subclass. All the settings are the
same as for Template::Declare's "init()" method except:
auto_alias
Additional option. Determines whether or not classes found under the
dispatch template's namespace are automatically aliased as described
in ""Auto-Aliasing".
strict
Set to true by default so that exceptional conditions are
appropriately fatal (it's false by default in Template::Declare).
Instance Methods
"process"
$view->process($c);
Renders the template specified in "$c->stash->{template}" or
"$c->action" (the private name of the matched action). Calls render() to
perform actual rendering. Output is stored in "$c->response->body".
"render"
my $output = $view->render( $c, $template_name, $args );
Renders the given template and returns output. Dies on error.
If $args is a hash reference, it will be passed to the template.
Otherwise, "$c->stash" will be passed if $c is defined.
SEE ALSO
Catalyst, Catalyst::View::TT, Catalyst::Helper::View::TD,
Catalyst::Helper::View::TDSite, Template::Manual
Author
David E. Wheeler <david@justatheory.com>
Copyright
This program is free software. You can redistribute it and/or modify it
under the same terms as Perl itself.