Improved field_group_fields_nest() [#1142618]

I was experiencing an error with nested groups not being rendered. So I debugged the code down to the field_group_fields_nest() function. Knowing the source of the problem I looked for updates. The current dev of this module does solve the error I experienced but I had already seen that this function could be written a lot easier.

So I decided to rewrite the function and post it here as an improvement:

function field_group_fields_nest(&$root_element) {
  // Create all groups and keep a flat list of references to these groups.
  $group_references = array();
  foreach ($root_element['#groups'] as $group_name => $group) {
    $root_element[$group_name] = array();
    $group_references[$group_name] = &$root_element[$group_name];
  }

  // Move all children to their parents. Use the flat list of references for
  // direct access as we don't know where in the root_element hierarchy the
  // parent currently is situated.
  foreach ($root_element['#group_children'] as $child_name => $parent_name) {
    // Block denied fields (#access) before they are put in groups.
    if (!isset($root_element[$child_name]['#access']) || $root_element[$child_name]['#access']) {
      // Use a reference as this may be a group, not a field.
      $group_references[$parent_name][$child_name] = &$root_element[$child_name];
    }
    // The child has been copied to its parent: remove it from the root element.
    unset($root_element[$child_name]);
  }

  // Bring extra element wrappers to achieve a grouping of fields.
  // This will mainly be prefix and suffix altering.
  foreach ($root_element['#groups'] as $group_name => $group) {
    field_group_pre_render($group_references[$group_name], $group, $root_element);
  }
}

Advantages;
- no nested loops.
- no recursion.
- (consequence of the first 2) more performant.
- field_pre_render called when the whole hierarchy has been built.
- less side effects: #group_children (and #groups) array elements remain unaffected.

I think this will be a nice improvement of your code.

Comments

Comment #1

fietserwin

Le Mont-Dore

CreditAttribution: fietserwin commented 29 April 2011 at 19:34

Further improving the code:
- the calling function can be cleaned
- documentation adapted to the new code

function field_group_build_pre_render($element) {

  // Merge our #fieldgroups with #groups to avoid conflicts on fieldset types.
  $element['#groups'] = array_merge($element['#groups'], $element['#fieldgroups']);

  // Nest the fields in the corresponding field groups.
  field_group_fields_nest($element);

  // Allow others to alter the pre_rendered build.
  drupal_alter('field_group_build_pre_render', $element);

  return $element;
}

/**
 * Builds the element hierarchy based on the defined grouping (as can be found
 * in the #group and #group_child elements of the given element).
 *
 * @param array $element
 *   The element that is to be regrouped hierarchically.
 */
function field_group_fields_nest(&$element) {
  // Create all groups and keep a flat list of references to these groups.
  $group_references = array();
  foreach ($element['#groups'] as $group_name => $group) {
    $element[$group_name] = array();
    $group_references[$group_name] = &$element[$group_name];
  }

  // Move all children to their parents. Use the flat list of references for
  // direct access as we don't know where in the root_element hierarchy the
  // parent currently is situated.
  foreach ($element['#group_children'] as $child_name => $parent_name) {
    // Block denied fields (#access) before they are put in groups.
    if (!isset($element[$child_name]['#access']) || $element[$child_name]['#access']) {
      // If this is a group, we have to use a reference to keep the reference
      // list intact (but if it is a field we don't mind).
      $group_references[$parent_name][$child_name] = &$element[$child_name];
    }
    // The child has been copied to its parent: remove it from the root element.
    unset($element[$child_name]);
  }

  // Bring extra element wrappers to achieve a grouping of fields.
  // This will mainly be prefix and suffix altering.
  foreach ($element['#groups'] as $group_name => $group) {
    field_group_pre_render($group_references[$group_name], $group, $element);
  }
}