NAME
CGI::Application::Plugin::HTDot - Enable "magic dot" notation in
CGI::Application-derived applications that use HTML::Template for their
templating mechanism.
VERSION
Version 0.07
SYNOPSIS
# In your CGI::Application-derived base class. . .
use base ("CGI::Application::Plugin::HTDot", "CGI::Application");
# Later, in a run mode far, far away. . .
sub view {
my $self = shift;
my $username = $self->query->param( 'user' );
my $user = My::Users->retrieve( $username );
my $tmpl_view = $self->load_tmpl( 'view_user.tmpl' );
# The magic happens here! Pass our Class::DBI object
# to the template and display it
$tmpl_view->param( user => $user );
return $tmpl_view->output;
}
DESCRIPTION
Imagine this: you've written a lot of code based upon CGI::Application,
and also with HTML::Template because the two have always had such a high
level of integration. You reach a situation (many times, perhaps) where
you could really use the power and convenience of being able to pass
objects to your templates and call methods of those objects from within
your template (ala Template Toolkit), but your development schedule
doesn't give you the time to learn (much less migrate to!) Template
Toolkit or AnyTemplate. Well, you need fret no more!
"CGI::Application::Plugin::HTDot" helps you bring the power of the magic
dot to your HTML::Template-based templates from within your
CGI::Application-derived webapps.
CGI::Application::Plugin::HTDot provides the glue between
CGI::Application, HTML::Template::Pluggable and
HTML::Template::Plugin::Dot. It overrides the "load_tmpl()" method
provided with CGI::Application and replaces it with one that turns on
the magic dot in HTML::Template. The "load_tmpl()" method provided here
is 100% compatible with the one found in a stock CGI::Application app,
so using this plugin does not require refactoring of any code. You can
use the magic dot in your application and templates going forward, and
refactor older code to use it as your schedule permits.
When you have lots of apps and lots of templates, and no means to switch
to Template Toolkit, this will make your life infinitely easier.
For more information about the magic dot, see
HTML::Template::Plugin::Dot.
As of version 4.31 of " CGI::Application ", you can use the "
html_tmpl_class() " method as an alternative to this plugin. TIMTOWTDI.
METHODS
load_tmpl()
For the most part, this is the exact "load_tmpl()" method from
CGI::Application, except it uses HTML::Template::Pluggable and
HTML::Template::Plugin::Dot instead of HTML::Template.
See the CGI::Application reference for more detailed information on what
parameters can be passed to "load_tmpl()".
Extending load_tmpl()
There are times when the basic "load_tmpl()" functionality just isn't
enough. Many HTML::Template developers set "die_on_bad_params" to 0 on
all of their templates. The easiest way to do this is by replacing or
extending the functionality of CGI::Application's "load_tmpl()" method.
This is still possible using the plugin.
The following code snippet illustrates one possible way of achieving
this:
sub load_tmpl {
my ($self, $tmpl_file, @extra_params) = @_;
push @extra_params, "die_on_bad_params", "0";
push @extra_params, "cache", "1";
return $self->SUPER::load_tmpl($tmpl_file, @extra_params);
}
This plugin honors the "load_tmpl()" callback. Any "load_tmpl()"-based
callbacks you have created will be executed as intended:
DEFAULT PARAMETERS
By default, this plugin will automatically add a parameter 'c' to your
template that will return your CGI::Application object. This will allow
you to access any methods in your application from within your template.
This allows for some powerful actions in your templates. For example,
your templates can access query parameters, or if you use the excellent
CGI::Application::Plugin::Session module, you can access session
parameters:
Hello <tmpl_var c.session.param('username')>!
<a href="<tmpl_var c.query.self_url>">Reload this page</a>
Another useful plugin that can use this feature is the
CGI::Application::Plugin::HTMLPrototype plugin, which gives easy access
to the prototype.js JavaScript library:
<tmpl_var c.prototype.define_javascript_functions>
<a href="#" onclick="javascript:<tmpl_var c.prototype.visual_effect( 'Appear', 'extra_info' )>; return false;">Extra Info</a>
<div style="display: none" id="extra_info">Here is some more extra info</div>
With this extra flexibility comes some responsibilty as well. It could
lead down a dangerous path if you start making alterations to your
object from within the template. For example you could call c.header_add
to add new outgoing headers, but that is something that should be left
in your code, not in your template. Try to limit yourself to pulling in
information into your templates (like the session example above does).
This plugin will respect your current "die_on_bad_params" setting. If
"die_on_bad_params" is set to 1 and your template does not use 'c', the
plugin will not attempt to pass the CGI::Application object to your
template. In other words, it does not force your application to set
"die_on_bad_params" to 0 to accomplish this action.
AUTHOR
Jason A. Crome, "<cromedome@cpan.org>"
BUGS
Please report any bugs or feature requests to
"bug-cgi-application-plugin-htdot@rt.cpan.org", or through the web
interface at
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=CGI-Application-Plugin-H
TDot>. I will be notified, and then you'll automatically be notified of
progress on your bug as I make changes.
ACKNOWLEDGMENTS
Thanks and credit needs to be given to Jesse Erlbaum and Mark Stosberg
for the original "load_tmpl()" method that this is based on, to Rhesa
Rozendaal and Mark Stosberg for their work on enabling the magic dot in
HTML::Template, Cees Hek for his idea (and tutorial on how) to use
multiple inheritance to make this plugin work, and to the usual crowd in
#cgiapp on irc.perl.org for making this all worthwhile for me :)
An extra special thanks to Cees Hek for the inspiration, code, and
examples to implement the 'c' parameter in templates.
SEE ALSO
CGI::Application, HTML::Template, HTML::Template::Pluggable,
HTML::Template::Plugin::Dot, CGI::Application::Plugin::TT.
COPYRIGHT & LICENSE
Copyright (C) 2005-2007, Jason A. Crome. All rights reserved.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.