simple and nice

Doing an upgrade of my app from Drupal 4.7.x to Drupal 5.x. The big difference in Form API in Drupal 5.x vs 4.7.x is on how drupal_get_form (the way form is build) work. In 4.7.x, drupal_get_form work through a push model where we supply the array of form definition to the function call:-

function customer_edit($customer) {
  $form = array();
  $form['customer_name'] = array(
    '#type' => 'textfield',
    '#title' => 'Name',
    '#default_value' => $customer->name
  );
  return drupal_get_form($form, 'customer_edit');
}

The second argument is the form_id. In 5.x however, this has changed to pull model where the form definition need to be build in a dedicated builder function.

function customer_build_form() {
  $form = array();
  $form['customer_name'] = array(
    '#type' => 'textfield',
    '#title' => 'Name',
    '#default_value' => $customer->name
  );
  return $form;
}

function customer_edit($customer) {
  return drupal_get_form('customer_build_form');
}

Now the first argument to drupal_get_form function call is the name of the form builder function. Another way is to implement the new hook introduced hook_forms to do some complex mapping of form_id to builder function.

function customer_forms() {
  $forms = array();
  $forms['customer_edit'] = array(
    'callback' => 'customer_build_form'
  );
  $forms['customer_add'] = array(
    'callback' => 'customer_build_form'
  );
}

function customer_edit($customer) {
  return drupal_get_form('customer_edit');
}

I got some problems when using the hook_forms approach. No errors from PHP process and Nginx just gave an ‘500 server error’. Further checking revealed that the problem was with the form_id which is similar to already defined function name. My guess was some recursive calling occured when drupal_get_form first try to call a function named customer_edit as being used in the form_id. Unfortunately, the calling function was also a customer_edit. So the fix is, never used form_id that is similar to already defined function since drupal_get_form will first look for it instead of relying on the hook_forms if it is implemented.