Example.pm

package Example::Controller::Root;

use Moose;
use MooseX::MethodAttributes;

extends 'Catalyst::Controller';

sub root :Chained(/) PathPart('') CaptureArgs(0) { } 

  # map body params directly to action args
  sub login :Chained(root) PathPart(login) Args(0) Body(username Str, password Str) ($self, $c, $username, $password)
  {
    my $error = '';
    if($c->req->method eq 'POST') {
      $c->redirect_to_action('home') if $c->authenticate({
          username=>$username,
          password=>$password,
        });
      $error = 'User not found!';
    }
    $c->stash(error => $error);
  }

  # map body params to model 'LoginCredentials', which does an expected role
  sub login :Chained(root) PathPart(login) Args(0) PostParams(credentials LoginCredentials) ($self, $c, $credentials)
  {
    my $error = '';
    if($c->req->method eq 'POST') {
      $c->redirect_to_action('home') if $c->authenticate({
          username=>$credentials->username,
          password=>$credentials->password,
        });
      $error = 'User not found!';
    }
    $c->stash(error => $error);
  }

sub end : ActionClass('RenderView') {}

__PACKAGE__->config(namespace=>'');
__PACKAGE__->meta->make_immutable;


package Example::Model::LoginCredentials;

use Moose;
use CatalystX::Injection;
extends 'Catalyst::Model';

has 'username' => (is=>'ro', required=>1, body_param=>1);
has 'password' => (is=>'ro', required=>1, body_param=>1);

__PACKAGE__->meta->make_immutable;