Let extra fields to be indexed using mapping option

Hi,

The extrafields are not taken into index when they are defined using mapping options as the only fields allowed are the ones defined in the field_config tableb here is the current mapping indexing function

/**
 * Returns array containing information about node fields that should be indexed
 */
function apachesolr_entity_fields($entity_type = 'node') {
  $fields = &drupal_static(__FUNCTION__, array());

  if (!isset($fields[$entity_type])) {
    $fields[$entity_type] = array();

    $mappings = module_invoke_all('apachesolr_field_mappings');
    foreach (array_keys($mappings) as $key) {
      // Set all values with defaults.
      $defaults = array(
          'dependency plugins' => array('bundle', 'role'),
          'map callback' => FALSE,
          'name callback' => '',
          'hierarchy callback' => FALSE,
          'indexing_callback' => '',
          'index_type' => 'string',
          'facets' => FALSE,
          'facet missing allowed' => FALSE,
          'facet mincount allowed' => FALSE,
          // Field API allows any field to be multi-valued.
          'multiple' => TRUE,
        );
      if ($key !== 'per-field') {
        $mappings[$key] += $defaults;
      }
      else {
        foreach (array_keys($mappings[$key]) as $field_key) {
          $mappings[$key][$field_key] += $defaults;
        }
      }
    }

    // Allow other modules to add or alter mappings.
    drupal_alter('apachesolr_field_mappings', $mappings, $entity_type);

    $modules = system_get_info('module');
    $instances = field_info_instances($entity_type);
    foreach (field_info_fields() as $field_name => $field) {
      $row = array();
      if (isset($field['bundles'][$entity_type]) && (isset($mappings['per-field'][$field_name]) || isset($mappings[$field['type']]))) {
        // Find the mapping.
        if (isset($mappings['per-field'][$field_name])) {
          $row = $mappings['per-field'][$field_name];
        }
        else {
          $row = $mappings[$field['type']];
        }
        // The field info array.
        $row['field'] = $field;

        // @todo: for fields like taxonomy we are indexing multiple Solr fields
        // per entity field, but are keying on a single Solr field name here.
        $function = !empty($row['name callback']) ? $row['name callback'] : NULL;
        if ($function && is_callable($function)) {
          $row['name'] = $function($field);
        }
        else {
          $row['name'] = $field['field_name'];
        }
        $row['module_name'] = $modules[$field['module']]['name'];
        // Set display name
        $display_name = array();
        foreach ($field['bundles'][$entity_type] as $bundle) {
          if (empty($instances[$bundle][$field_name]['display']['search_index']) || $instances[$bundle][$field_name]['display']['search_index'] != 'hidden') {
            $row['display_name'] = $instances[$bundle][$field_name]['label'];
            $row['bundles'][] = $bundle;
          }
        }
        // Only add to the $fields array if some instances are displayed for the search index.
        if (!empty($row['bundles'])) {
          // Use the Solr index key as the array key.
          $fields[$entity_type][apachesolr_index_key($row)] = $row;
        }
      }
    }
    
  }
  return $fields[$entity_type];
}

As you can see above the only fields that are taken into index are the ones that come from field_info_fields() function.

Attached the patch to include the fields that are defined in the extrafields hook that allows external modules to define mapping option that can be indexed.

Regards,

Julian Mancera