NAME
    Catalyst::View::TT - Template View Class

SYNOPSIS
    # use the helper to create your View

        myapp_create.pl view Web TT

    # add custom configration in View/Web.pm

        __PACKAGE__->config(
            # any TT configuration items go here
            TEMPLATE_EXTENSION => '.tt',
            CATALYST_VAR => 'c',
            TIMER        => 0,
            ENCODING     => 'utf-8'
            # Not set by default
            PRE_PROCESS        => 'config/main',
            WRAPPER            => 'site/wrapper',
            render_die => 1, # Default for new apps, see render method docs
            expose_methods => [qw/method_in_view_class/],
        );

    # add include path configuration in MyApp.pm

        __PACKAGE__->config(
            'View::Web' => {
                INCLUDE_PATH => [
                    __PACKAGE__->path_to( 'root', 'src' ),
                    __PACKAGE__->path_to( 'root', 'lib' ),
                ],
            },
        );

    # render view from lib/MyApp.pm or
    lib/MyApp::Controller::SomeController.pm

        sub message : Global {
            my ( $self, $c ) = @_;
            $c->stash->{template} = 'message.tt2';
            $c->stash->{message}  = 'Hello World!';
            $c->forward( $c->view('Web') );
        }

    # access variables from template

        The message is: [% message %].

        # example when CATALYST_VAR is set to 'Catalyst'
        Context is [% Catalyst %]
        The base is [% Catalyst.req.base %]
        The name is [% Catalyst.config.name %]

        # example when CATALYST_VAR isn't set
        Context is [% c %]
        The base is [% base %]
        The name is [% name %]

DESCRIPTION
    This is the Catalyst view class for the Template Toolkit. Your
    application should defined a view class which is a subclass of this
    module. Throughout this manual it will be assumed that your application
    is named MyApp and you are creating a TT view named Web; these names are
    placeholders and should always be replaced with whatever name you've
    chosen for your application and your view. The easiest way to create a
    TT view class is through the myapp_create.pl script that is created
    along with the application:

        $ script/myapp_create.pl view Web TT

    This creates a MyApp::View::Web.pm module in the lib directory (again,
    replacing "MyApp" with the name of your application) which looks
    something like this:

        package FooBar::View::Web;
        use Moose;

        extends 'Catalyst::View::TT';

        __PACKAGE__->config(DEBUG => 'all');

    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 TT view class.

        # In MyApp or MyApp::Controller::SomeController

        sub end : Private {
            my( $self, $c ) = @_;
            $c->forward( $c->view('Web') );
        }

    But if you are using the standard auto-generated end action, you don't
    even need to do this!

        # in MyApp::Controller::Root
        sub end : ActionClass('RenderView') {} # no need to change this line

        # in MyApp.pm
        __PACKAGE__->config(
            ...
            default_view => 'Web',
        );

    This will Just Work. And it has the advantages that:

    *   If you want to use a different view for a given request, just set <<
        $c->stash->{current_view} >>. (See Catalyst's "$c->view" method for
        details.

    *   << $c->res->redirect >> is handled by default. If you just forward
        to "View::Web" in your "end" routine, you could break this by
        sending additional content.

    See Catalyst::Action::RenderView for more details.

  CONFIGURATION
    There are a three different ways to configure your view class. The first
    way is to call the "config()" method in the view subclass. This happens
    when the module is first loaded.

        package MyApp::View::Web;
        use Moose;
        extends 'Catalyst::View::TT';

        __PACKAGE__->config({
            PRE_PROCESS  => 'config/main',
            WRAPPER      => 'site/wrapper',
        });

    You may also override the configuration provided in the view class by
    adding a 'View::Web' section to your application config.

    This should generally be used to inject the include paths into the view
    to avoid the view trying to load the application to resolve paths.

        .. inside MyApp.pm ..
        __PACKAGE__->config(
            'View::Web' => {
                INCLUDE_PATH => [
                    __PACKAGE__->path_to( 'root', 'templates', 'lib' ),
                    __PACKAGE__->path_to( 'root', 'templates', 'src' ),
                ],
            },
        );

    You can also configure your view from within your config file if you're
    using Catalyst::Plugin::ConfigLoader. This should be reserved for
    deployment-specific concerns. For example:

        # MyApp_local.conf (Config::General format)

        <View Web>
          WRAPPER "custom_wrapper"
          INCLUDE_PATH __path_to('root/templates/custom_site')__
          INCLUDE_PATH __path_to('root/templates')__
        </View>

    might be used as part of a simple way to deploy different instances of
    the same application with different themes.

  DYNAMIC INCLUDE_PATH
    Sometimes it is desirable to modify INCLUDE_PATH for your templates at
    run time.

    Additional paths can be added to the start of INCLUDE_PATH via the stash
    as follows:

        $c->stash->{additional_template_paths} =
            [$c->config->{root} . '/test_include_path'];

    If you need to add paths to the end of INCLUDE_PATH, there is also an
    include_path() accessor available:

        push( @{ $c->view('Web')->include_path }, qw/path/ );

    Note that if you use include_path() to add extra paths to INCLUDE_PATH,
    you MUST check for duplicate paths. Without such checking, the above
    code will add "path" to INCLUDE_PATH at every request, causing a memory
    leak.

    A safer approach is to use include_path() to overwrite the array of
    paths rather than adding to it. This eliminates both the need to perform
    duplicate checking and the chance of a memory leak:

        @{ $c->view('Web')->include_path } = qw/path another_path/;

    If you are calling "render" directly then you can specify dynamic paths
    by having a "additional_template_paths" key with a value of additonal
    directories to search. See "CAPTURING TEMPLATE OUTPUT" for an example
    showing this.

  Unicode
    Be sure to set "ENCODING => 'utf-8'" and use
    Catalyst::Plugin::Unicode::Encoding if you want to use non-ascii
    characters (encoded as utf-8) in your templates.

  RENDERING VIEWS
    The view plugin renders the template specified in the "template" item in
    the stash.

        sub message : Global {
            my ( $self, $c ) = @_;
            $c->stash->{template} = 'message.tt2';
            $c->forward( $c->view('Web') );
        }

    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", but because the default is to append
    '.tt', it would load "root/message.tt".

    The items defined in the stash are passed to the Template Toolkit for
    use as template variables.

        sub default : Private {
            my ( $self, $c ) = @_;
            $c->stash->{template} = 'message.tt2';
            $c->stash->{message}  = 'Hello World!';
            $c->forward( $c->view('Web') );
        }

    A number of other template variables are also added:

        c      A reference to the context object, $c
        base   The URL base, from $c->req->base()
        name   The application name, from $c->config->{ name }

    These can be accessed from the template in the usual way:

    <message.tt2>:

        The message is: [% message %]
        The base is [% base %]
        The name is [% 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 other purpose than
    displaying in the response, e.g. for sending an email, this is possible
    using Catalyst::Plugin::Email and the render method:

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

        $c->email(
          header => [
            To      => 'me@localhost',
            Subject => 'A TT Email',
          ],
          body => $c->view('Web')->render($c, 'email.tt', {
            additional_template_paths => [ $c->config->{root} . '/email_templates'],
            email_tmpl_param1 => 'foo'
            }
          ),
        );
      # Redirect or display a message
      }

  TEMPLATE PROFILING
    See "TIMER" property of the config method.

  METHODS
  new
    The constructor for the TT view. Sets up the template provider, and
    reads the application config.

  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".

    It is possible to forward to the process method of a TT view from inside
    Catalyst like this:

        $c->forward('View::Web');

    N.B. This is usually done automatically by Catalyst::Action::RenderView.

  render($c, $template, \%args)
    Renders the given template and returns output. Throws a
    Template::Exception object upon error.

    The template variables are set to %$args if $args is a hashref, or
    "$c->stash" otherwise. In either case the variables are augmented with
    "base" set to "$c->req->base", "c" to $c, and "name" to
    "$c->config->{name}". Alternately, the "CATALYST_VAR" configuration item
    can be defined to specify the name of a template variable through which
    the context reference ($c) can be accessed. In this case, the "c",
    "base", and "name" variables are omitted.

    $template can be anything that Template::process understands how to
    process, including the name of a template file or a reference to a test
    string. See Template::process for a full list of supported formats.

    To use the render method outside of your Catalyst app, just pass a undef
    context. This can be useful for tests, for instance.

    It is possible to forward to the render method of a TT view from inside
    Catalyst to render page fragments like this:

        my $fragment = $c->forward("View::Web", "render", $template_name, $c->stash->{fragment_data});

   Backwards compatibility note
    The render method used to just return the Template::Exception object,
    rather than just throwing it. This is now deprecated and instead the
    render method will throw an exception for new applications.

    This behaviour can be activated (and is activated in the default
    skeleton configuration) by using "render_die => 1". If you rely on the
    legacy behaviour then a warning will be issued.

    To silence this warning, set "render_die => 0", but it is recommended
    you adjust your code so that it works with "render_die => 1".

    In a future release, "render_die => 1" will become the default if
    unspecified.

  template_vars
    Returns a list of keys/values to be used as the catalyst variables in
    the template.

  config
    This method allows your view subclass to pass additional settings to the
    TT configuration hash, or to set the options as below:

  paths
    The list of paths TT will look for templates in.

  expose_methods
    The list of methods in your View class which should be made available to
    the templates.

    For example:

      expose_methods => [qw/uri_for_css/],

      ...

      sub uri_for_css {
        my ($self, $c, $filename) = @_;

        # additional complexity like checking file exists here

        return $c->uri_for('/static/css/' . $filename);
      }

    Then in the template:

      [% uri_for_css('home.css') %]

  "CATALYST_VAR"
    Allows you to change the name of the Catalyst context object. If set, it
    will also remove the base and name aliases, so you will have access them
    through <context>.

    For example, if CATALYST_VAR has been set to "Catalyst", a template
    might contain:

        The base is [% Catalyst.req.base %]
        The name is [% Catalyst.config.name %]

  "TIMER"
    If you have configured Catalyst for debug output, and turned on the
    TIMER setting, "Catalyst::View::TT" will enable profiling of template
    processing (using Template::Timer). This will embed HTML comments in the
    output from your templates, such as:

        <!-- TIMER START: process mainmenu/mainmenu.ttml -->
        <!-- TIMER START: include mainmenu/cssindex.tt -->
        <!-- TIMER START: process mainmenu/cssindex.tt -->
        <!-- TIMER END: process mainmenu/cssindex.tt (0.017279 seconds) -->
        <!-- TIMER END: include mainmenu/cssindex.tt (0.017401 seconds) -->

        ....

        <!-- TIMER END: process mainmenu/footer.tt (0.003016 seconds) -->

  "TEMPLATE_EXTENSION"
    a sufix to add when looking for templates bases on the "match" method in
    Catalyst::Request.

    For example:

      package MyApp::Controller::Test;
      sub test : Local { .. }

    Would by default look for a template in <root>/test/test. If you set
    TEMPLATE_EXTENSION to '.tt', it will look for <root>/test/test.tt.

  "PROVIDERS"
    Allows you to specify the template providers that TT will use.

        MyApp->config(
            name     => 'MyApp',
            root     => MyApp->path_to('root'),
            'View::Web' => {
                PROVIDERS => [
                    {
                        name    => 'DBI',
                        args    => {
                            DBI_DSN => 'dbi:DB2:books',
                            DBI_USER=> 'foo'
                        }
                    }, {
                        name    => '_file_',
                        args    => {}
                    }
                ]
            },
        );

    The 'name' key should correspond to the class name of the provider you
    want to use. The _file_ name is a special case that represents the
    default TT file-based provider. By default the name is will be prefixed
    with 'Template::Provider::'. You can fully qualify the name by using a
    unary plus:

        name => '+MyApp::Provider::Foo'

    You can also specify the 'copy_config' key as an arrayref, to copy those
    keys from the general config, into the config for the provider:

        DEFAULT_ENCODING    => 'utf-8',
        PROVIDERS => [
            {
                name    => 'Encoding',
                copy_config => [qw(DEFAULT_ENCODING INCLUDE_PATH)]
            }
        ]

    This can prove useful when you want to use the additional_template_paths
    hack in your own provider, or if you need to use
    Template::Provider::Encoding

  "CLASS"
    Allows you to specify a custom class to use as the template class
    instead of Template.

        package MyApp::View::Web;
        use Moose;
        extends 'Catalyst::View::TT';

        use Template::AutoFilter;

        __PACKAGE__->config({
            CLASS => 'Template::AutoFilter',
        });

    This is useful if you want to use your own subclasses of Template, so
    you can, for example, prevent XSS by automatically filtering all output
    through "| html".

  HELPERS
    The Catalyst::Helper::View::TT and Catalyst::Helper::View::TTSite helper
    modules are provided to create your view module. There are invoked by
    the myapp_create.pl script:

        $ script/myapp_create.pl view Web TT

        $ script/myapp_create.pl view Web TTSite

    The Catalyst::Helper::View::TT module creates a basic TT view module.
    The Catalyst::Helper::View::TTSite module goes a little further. It also
    creates a default set of templates to get you started. It also
    configures the view module to locate the templates automatically.

NOTES
    If you are using the CGI module inside your templates, you will
    experience that the Catalyst server appears to hang while rendering the
    web page. This is due to the debug mode of CGI (which is waiting for
    input in the terminal window). Turning off the debug mode using the
    "-no_debug" option solves the problem, eg.:

        [% USE CGI('-no_debug') %]

SEE ALSO
    Catalyst, Catalyst::Helper::View::TT, Catalyst::Helper::View::TTSite,
    Template::Manual

AUTHORS
    Sebastian Riedel, "sri@cpan.org"

    Marcus Ramberg, "mramberg@cpan.org"

    Jesse Sheidlower, "jester@panix.com"

    Andy Wardley, "abw@cpan.org"

    Luke Saunders, "luke.saunders@gmail.com"

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