perlmeditation zby This is a repost from my blog. In <a href="http://perlalchemy.blogspot.com/2009/06/packaging-cross-cutting-catalyst.html">Packaging cross cutting Catalyst features</a> I promised to start developing a generic Catalyst comment sub-system. Now I have incorporated the code samples into another experiment - <a href="http://github.com/gshank/ravlog/tree/master">ravlog</a> (a blog engine by Gerda Shank), and I would like to ask you what you think about it before releasing it to CPAN. <p> Here is the current API - any comments are welcome. First you need to declare the controller using the new Moose style: <code> package RavLog::Controller::View; use Moose; BEGIN { extends 'Catalyst::Controller'; with 'CatalystX::Comments::ControllerFormRole'; } has model_name => ( is => 'ro', isa => 'Str', default => 'DB' ); </code> The important part for us is of course <code>with 'CatalystX::Comments::ControllerFormRole'</code>, the <code>model_name</code> 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: <code> sub view : Chained('base') PathPart('view') Args(0) { my ( $self, $c, $id ) = @_; ... $self->stash_comment_form( $c, $self->article->id ); } </code> 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: <code> [% comment_form.render %] </code> For displaying the comments themselves ravlog already had some template code and I did not change it. <p> Next is the model part. The library assumes that the DBIC model contains a Comment Result class like <a href="http://github.com/gshank/ravlog/blob/2c88dd45416b4ad15a7ec6ca7309d72aa6181279/lib/RavLog/Schema/DB/Comment.pm">that one in ravlog</a>. 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 <a href="http://lists.scsys.co.uk/pipermail/dbix-class/2009-June/007984.html">I don't know how to do that</a>. <p> Now some more details. Thanks to <code>html_prefix</code> 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). <p> 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 <a href="http://perlalchemy.blogspot.com/2009/06/on-scaffoldings.html">scaffolding</a> - 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.