Rules Custom Condition for registration capacity

Question

I am trying to learn Rules and adding a custom condition. I need help to figure out what I am doing wrong.

My Condiiton set up:

function rules_example_capacity_condition_info() {
   $conditions = array(
     'rules_example_action_count_capacity' => array(
       'label' => t('Print capacity count on page'),
       'group' => t('Rules examples'),
       'parameters' => array(
         'count' => array('type' => 'value', 'label' => t('registration event count')),
         'capacity' => array('type' => 'value', 'label' => t('registration event capacity')),         
         ),
       ),
     );
     return $conditions; 
 }

and the function that calls it...

function rules_example_action_count_capacity($count, $capacity) {
    $reg_count = reg_count_load($count);
    return($reg_count->capacity == $capacity) ? true : false;
}  

I am trying to determine the count (how many people have registered so far) and the capacity. When the count and capacity are the same send an email.

I am not a developer so this is a little bit of a struggle. I found this series (http://nodeone.se/node/28) which is helpful, however there are so many smaller things I might be missing. Please help if you can. I am hoping that this will help more then just myself.

Thanks Tim

Answer 1

Looking at your function, I believe you need to rename it to something like mymodule_rules_condition_info. The hook you are trying to implement is hook_rules_condition_info(). Did you find that your custom condition was showing up when you were editing a rule?

function MYMODULE_rules_condition_info() {
   $conditions = array(
     'mymodule_event_is_at_capacity' => array(
       'label' => t('Event has reached maximum registrations'),
       'group' => t('MY MODULE'),
       'parameters' => array(
         'registration' => array(
            'type' => 'registration',
            'label' => t('The registration event'),
           ),         
         ),
       ),
     );
     return $conditions; 
 }

Semantically you may want to call your condition 'mymodule_event_is_at_capacity' and it should only need one parameter which is the capacity that you will provide in the Rules UI.

The function you will be writing mymodule_event_is_at_capacity($capacity) will query for the number of (active) users in Drupal, and if it is greater than or equal to $capacity, it will return TRUE.

All of this can be kicked off by add a new Rule that reacts on the "After saving a new user account" event.

Answer 2

Al Gorgeous Thank you for you help. Below is the final working example.

So, I had a lot to learn here. I have some help figuring this out.

I had to create a custom condition for Rules and then figure out the true/false statement to trigger the email. The hard part was having to figure out how to bring in the entity_id. I found this hacked way and it worked.

Hacked way to to grab the entity_id - How do I get entity_type and entity_id from any entity page?

function ecg_registration_rules_condition_info() {
  $conditions = array(
  'ecg_registration_event_is_at_capacity' => array(
       'label' => t('Event has reached maximum registrations'),
       'group' => t('MY MODULE'),
       'parameters' => array(
         'registration' => array(
            'type' => 'registration',
            'label' => t('The registration event capacity'),
           ),   
         ),
       ),
}

The function that tracks and triggers the capacity count.

function ecg_registration_event_is_at_capacity($registration) {
  $backtrace = debug_backtrace();
  foreach ($backtrace as $caller) {
    if ($caller['function'] == 'field_attach_view') {
      $entity_type = $caller['args'][0];
      $entity = $caller['args'][1];
      // do stuff with entity
      break;
    }  
  } 
  $entity_id = $entity->{'nid'};  
  $count =  registration_event_count($entity_type, $entity_id);
  $settings = registration_entity_settings($entity_type, $entity_id);
  if ($settings['capacity'] == 0) {
    return FALSE;
    break;
  } 
  if ($count >= $settings['capacity']) {   
      return TRUE;
  } 
  return FALSE;
}

Hope this helps someone else.