NAME
Catalyst::ActionRole::RequestModel - Inflate a Request Model
SYNOPSIS
package Example::Controller::Account;
use Moose;
use MooseX::MethodAttributes;
extends 'Catalyst::Controller';
sub root :Chained(/root) PathPart('account') CaptureArgs(0) { }
sub update :POST Chained('root') PathPart('') Args(0) Does(RequestModel) RequestModel(AccountRequest) {
my ($self, $c, $request_model) = @_;
## Do something with the $request_model
}
sub list :GET Chained('root') PathPart('') Args(0) Does(RequestModel) QueryModel(PagingModel) {
my ($self, $c, $paging_model) = @_;
}
__PACKAGE__->meta->make_immutable;DESCRIPTION
Moves creating the request model into the action class execute phase. The following two actions are essentially the same in effect:
sub update :POST Chained('root') PathPart('') Args(0) Does(RequestModel) RequestModel(AccountRequest) {
my ($self, $c, $request_model) = @_;
## Do something with the $request_model
}
sub update :POST Chained('root') PathPart('') Args(0) {
my ($self, $c) = @_;
my $request_model = $c->model('AccountRequest');
## Do something with the $request_model
}The main reason for moving this into the action attributes line is the thought that it allows us to declare the request model as meta data on the action and in the future we will be able to introspect that meta data at application setup time to do things like generate an Open API specification. Also, if you have several request models for the endpoint you can declare all of them on the attributes line and we will match the incoming request to the best request model, or throw an exception if none match. So if you have more than one this saves you writing that boilerplate code to chose and to handled the no match conditions.
You might also just find the code neater and more clean reading. Downside is for people unfamiliar with this system it might increase learning curve time.
METHOD ATTRIBUTES
This action role defines the following method attributes
RequestModel
Should be the name of a Catalyst::Model subclass that does <CatalystX::RequestModel::DoesRequestModel>. You may supply more than one value to handle different request content types (the code will match the incoming content type to an available request model and throw an CatalystX::RequestModel::Utils::InvalidContentType exception if none of the available models match.
Example of an action with more than one request model, which will be matched based on request content type.
sub update :POST Chained('root') PathPart('') Args(0) Does(RequestModel) RequestModel(AccountRequestForm) RequestModel(AccountRequestJSON) {
my ($self, $c, $request_model) = @_;
## Do something with the $request_model
}Also, if more than one model matches, you'll get an instance of each matching model.
QueryModel
Should be the name of a Catalyst::Model subclass that does CatalystX::QueryModel::DoesQueryModel. You may supply more than one value to handle different request content types (the code will match the incoming content type to an available query model and throw an CatalystX::RequestModel::Utils::InvalidContentType exception if none of the available models match.
sub root :Chained(/root) PathPart('users') CaptureArgs(0) { }
sub list :GET Chained('root') PathPart('') Args(0) Does(RequestModel) QueryModel(PagingModel) {
my ($self, $c, $paging_model) = @_;
}NOTE: In the situation where you have QueryModel and Request model for the same action, the request models will be added first to the action argument list, followed by the query models, no matter what order they appear in the action method declaration. This is due to a limitation in how Catalyst collects the subroutine attributes (we can't know the order of dissimilar attributes since this information is stored in a hash, not an array, and Catalyst allows a controller to inherit attributes from a base class, or from a role or even from configutation). However the order of QueryModels and RequestModels independently are preserved.