[Catalyst] Why is $c undefined?

Craig Chant craig at homeloanpartnership.com
Tue Oct 30 11:09:55 GMT 2012

Thanks Ian,

The hierarchy is something that I am finding mind-blowing at the moment,    "$self->jqgrid->render($self," , you are calling methods jqgrid->render on $self, passing in $self, I'm sure it makes sense to you :-)

One thing I would like clarification with if possible.

Where do I put code that requires the use of more than one model?

Do I create a separate model that acts as an interface between the other models?

You see I have two SQL servers in opposite ends of the country and so I have a model built on Model::DBI that can access one server and another Model that can access the other, but I have functionality that needs data from both , do some calculations and output accordingly.

I assume this does not go in the controller, but I create an interface model with the required methods and functionality that the controller uses?



-----Original Message-----
From: Ian Docherty [mailto:catalyst at iandocherty.com]
Sent: 30 October 2012 07:22
To: The elegant MVC web framework
Subject: Re: [Catalyst] Why is $c undefined?

On 29 October 2012 21:01, Craig Chant <craig at homeloanpartnership.com> wrote:
> I have read and seen frameworks such as Mojolicious encourage a shrinkage of the Model and move alot of functionality to the Controller, so there is a paradigm which seems to imply it is ok to do more stuff in the Controller, but I am leaning towards having the main code in the Model and then bolting it together via the Controller.
I can understand why you get this impression, I think a lot of people end up putting code in the Controller when they first start using MVC (I did so myself in the past).

The Model should be external to your Catalyst app (or whatever framework you use) so that you can use it in things like cron jobs. It also makes testing easier if your Model is separate from your Catalyst app. Look at using something like Catalyst::Model::Adaptor as a thin shell to add your external Model into Catalyst.

I am moving more and more into making my Controllers as thin as possible. Logic that I might have previously put into the Controller, I either put into the Model or I create helper functions. Here is an example of a Controller (from Mojolicious as it happens but that is not important)

sub user_list {
    my ($self) = @_;

    $self->jqgrid->render($self, {
        rs      => $self->schema->resultset('User')->search_rs,
        filters => {},
        rows    => [qw(id name)],

It's not important to know what is going on here, but this Controller gets a list of all users, formats the data for use in the jQuery jqGrid allows for sorting and filtering and outputs the data in JSON format. The point being, the controller code is kept simple and 'thin'
and yet it does a lot of work behind the scenes.

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