/ 
CGI-Application-Plugin-ErrorPage-1.21
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/ CGI::Application::Plugin::ErrorPage

NAME

CGI::Application::Plugin::ErrorPage - A simple error page plugin for CGI::Application

SYNOPSIS

use CGI::Application::Plugin::ErrorPage 'error';

sub my_run_mode {
  my $self = shift;

  eval { .... };

  if ($@) {
      # Send the gory details to the log for the developers
      warn "$@";
      
      # Send a comprehensible message to the users
      return $self->error(
          title => "Technical Failure',
          msg   => "There was a techical failure during the operation.",
      );
  }

}

DESCRIPTION

This plugin provides a shortcut for the common need of returning a simple error message to the user.

You are encouraged to provide a template file so that the error messages can be presented with a design consistent with the rest of your application.

A simple design is provided below to get to you started.

A better default error page.

If you don't install an AUTOLOAD run mode in the normal way in setup, this plugin will automatically install a reasonable default at the prerun stage, which returns an error page like this:

return $c->error(
    title => 'The requested page was not found.',
    msg => "(The page tried was: ".$c->get_current_runmode.")"
);

Relation to error_mode()

CGI::Application includes error_mode() to provide custom handling when the application dies. This error() routine provides a shortcut for displaying error messages to the user. So, they both have a place on their own, and it could make sense to use them together. In your 'error_mode' routine, you might call error() to return a message to the user:

$self->error( title => 'Technical Failure', msg => 'There was a technical failure' );

Suggested Uses

Some common cases for returning error messages to the user include:

* "Technical Failure" - The software failed unexpectedly  
* "Insufficient Information" - some required query parameter was missing 
* "Request Not Understood" - Some value we received in the query just didn't make sense.

Silliness

[22:36] <rjbs> Techno Failure.  We were cruising along and rocking out while fulfilling your request, but then the music stopped and we sort of got distracted.
[22:36] <rjbs> Tek Failure.  Too busy reading Shatner novels to respond to your request.

METHODS

error()

return $self->error(
    title => "Technical Failure',
    msg   => "There was a techical failure during the operation",
);

Nothing fancy, just a shortcut to load a template meant to display errors. I've used it for the past several years, and it's been very handy to always have around on projects to quickly write error handling code.

It tries to load a template file named 'error.html' to display the error page.

If you want to use a different location, I recommend putting something like this in your base class, so you only have to provide your error template location once.

# In this case, intentionally *don't* import 'error' to avoid a "redefined" warning.
use CGI::Application::Plugin::ErrorPage;
sub error {
     my $c = shift;
     return $c->CGI::Application::Plugin::ErrorPage::error(
         tmpl => $self->cfg('ROOT_URI').'/path/to/my/alternate/error/file.html',
         @_,
     );
}

This module intentionally ignores any tmpl_path() set by application, since this is usually an indication of where the intended file is located, not the error template. This exceptional handling of the tmpl_path() is one of the only value added bits of logic that this plugin adds. The rest of it is primarily a simple recommendation for error page handling wrapped up as a module.

If you don't want this behavior, it's simple enough just to roll your own error() page method and skip using this plugin. Here's the simple essential code:

use Params::Validate ':all';
sub error {
    my $self  = shift;
    my %p = validate(@_, { title => SCALAR, msg => SCALAR });
    my $t = $self->load_tmpl;
    $t->param( title => $p{title}, msg => $p{msg} );
    return $t->output;
}

Example error.html

Here's a very basic example of an error.html file to get you started.

<!DOCTYPE html
        PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
         "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" lang="en-US" xml:lang="en-US">
<head>
<title><!-- tmpl_var title escape=HTML --></title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
</head>
<body>
<h1><!-- tmpl_var title escape=HTML--></h1>
<p><!-- tmpl_var msg escape=HTML --></p>
</body>
</html>

We manage site-wide designs with Dreamweaver and keep a basic 'error.html' that uses a generic Dreamweaver 'page.dwt' template with standard EditableRegion names. That way, we can copy this error.html into a new Dreamweaver-managed project and have the new design applied to it easily through Dreamweaver.

SUPPORT

Ask for help on the CGI::Application mailing list. Report bugs and wishes through the rt.cpan.org bug tracker.

AUTHOR

Mark Stosberg
CPAN ID: MARKSTOS
mark@summersault.com

COPYRIGHT

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

The full text of the license can be found in the LICENSE file included with this module.

SEE ALSO

perl(1).