This is a repost from my blog. In Packaging cross cutting Catalyst features I promised to start developing a generic Catalyst comment sub-system. Now I have incorporated the code samples into another experiment - ravlog (a blog engine by Gerda Shank), and I would like to ask you what you think about it before releasing it to CPAN.

Here is the current API - any comments are welcome. First you need to declare the controller using the new Moose style:

package RavLog::Controller::View;

use Moose;
BEGIN {
   extends 'Catalyst::Controller';
   with 'CatalystX::Comments::ControllerFormRole';
}

has model_name => ( is => 'ro', isa => 'Str', default => 'DB' );
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The important part for us is of course with 'CatalystX::Comments::ControllerFormRole', the model_name attribute should hold the name of the model CatalystX::Comments will use to store the comments. After the declarations you can use CatalystX::Comments to put the comment form on the stash:

sub view : Chained('base') PathPart('view') Args(0)
{
   my ( $self, $c, $id ) = @_;

...
   
   $self->stash_comment_form( $c, $self->article->id );
}
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That's the whole controller part - what it handles is generating the form for display and saving the submitted comments. In the view templates you need to add:

[% comment_form.render %]
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For displaying the comments themselves ravlog already had some template code and I did not change it.

Next is the model part. The library assumes that the DBIC model contains a Comment Result class like that one in ravlog. Of course it does not need to have all of the columns, and can also have other columns - but these are the columns that will be filled by the CatalystX::Comments form. Ideally that model part should be a Result base class - so that it can be subclassed and adapted to local needs (for example the belongs_to relationship to article needs to be changed), but for now I don't know how to do that.

Now some more details. Thanks to html_prefix all parameters sent from this form are prefixed with the form name - so this form can be added to pages with other forms, it will recognize it's parameters. The comments are saved only when the HTTP method used is POST, and after a successful comment creation the user is redirected to the same page (this seems a bit constraining - but see next paragraph - this is only meant to be temporary solution - I try to keep the API simple).

Of course I understand that this can never cover the needs of a comment sub-system in a mature social web site. I am thinking about it as more of scaffolding - code that let's you quickly develop a feature, see how it integrates with the rest of the user experience, formulate a more complete requirements list - and replace it part by part.

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