This is another one in my series: I post this here in case I forget how I did it last time... :-)

I just had the following problem in my Catalyst app:
As a model I am using a class that has nothing to do with the Catalyst app itself. I want to instantiate objects of this class once per request, so I extend Catalyst::Model::Factory::PerRequest like this (my class needs its parameters to "new" in list form, not hashref): 

package MyApp::Model::ProblemSolver;
use Moose;
use namespace::autoclean;

extends 'Catalyst::Model::Factory::PerRequest';

__PACKAGE__->config(
  class => 'MyNonCatalyst::ProblemSolver',
);

# provide arguments as a list  instead of hash-ref
sub mangle_arguments {
  my ($self, $args) = @_;
  return %$args;
}

[download]

Now, objects of the MyNonCatalyst::ProblemSolver class need some parameters that go well in the app's config file, e.g. details for a database connection. It also needs parameters that will depend on input from the user of the site.
I found out that I can add this to the above model class (this is using the Moose way of overriding a parent's method and calling SUPER): 

override 'prepare_arguments' => sub {
  my ($self, $c) = @_; 
  my $config_params = super();
  my $passed_in_params = $c->stash->{problem_solver_args};
  my %merged_args = ( %$config_params, %$passed_in_params ); 
  return \%merged_args;
}; # prepare_arguments

[download]
This will merge the parameters from the config file and those that were passed in from the controller in such a way that the controller arguments override the config defaults. In my controller I can now do something like this: 

$c->stash->{problem_solver_args}{some_param} = $user_input1 if $user_i
+nput1;
$c->stash->{problem_solver_args}{some_other_param} = $user_input2;

my $problem_solver = $c->model('ProblemSolver');
my $result = $problem_solver->solve_problem();

[download]
in my my_app.yaml config file for the app I have: 
Model::ProblemSolver:
  args:
    database: a_database_of_solved_problems
    some_param: SOME_DEFAULT_VALUE

[download]
This means that the database name is always taken from the app's config file but 'some_param' will be taken from user input if there is any or the above default is used to instantiate an object of the model class.

In reply to instantiate objects from non-Catalyst model classes with parameters by tospo

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