Add Generic Foreign Key Getter

Adding an initial patch here to see if there is any wider spread interest. The patch works as advertised, tested on 2 installs that I maintain. The specification of the PK & FK fields is currently a text box, which definitely needs to be a drop-down select for security and stability, but for testing purposes this works.

I am having trouble adding the include file that powers this getter, however. I followed the instructions on , but cannot seem to get it t o add the file contents to the diff. I am pasting it below, and would be delighted to get some guidance from someone.

<?php
/**
 * @file
 *  Contains class for an entity that is linked to the base entity by an FK column (could be a field or other)
 */

/**
 * Form Entity that loads an entity from an id stored in config.
 */
class FlexiformFormFKEntityLoad extends FlexiformFormEntityBase {

  /**
   * {@inheritdoc}
   */
  public function getEntity() {

    $id = $this->settings['entity_id'];

    // Don't do anything if the $id is empty.
    if (empty($id)) {
      return FALSE;
    }
    
    parent::getEntity();
    $base = $this->manager->getBaseEntity();
    $bt = $this->manager->getEntityType('base_entity');
    list($baseid, $rid, $bun) = entity_extract_ids($bt, $base);
    dpm($base, "Base Entity");
    $efq = new EntityFieldQuery(); 
    $efq->entityCondition('entity_type', $this->entity_type);
    $efq->propertyCondition($this->settings['fk_col'], $baseid, '=');
    drupal_set_message("entityCondition('entity_type', $this->entity_type)");
    drupal_set_message($this->settings['fk_col'] . ", $baseid, '='");
    $result = $efq->execute();
    dpm($result, "efq: ");
    if (isset($result[$this->entity_type])) {
      $rez = array_shift($result[$this->entity_type]);
      if (property_exists($rez, $this->settings['pk_col'])) {
        $id = $rez->{$this->settings['pk_col']};
    dpm($id, "pkid: ");
        $valid = TRUE;
      }
    }
    // Don't do anything if the $id is empty.
    if (empty($id)) {
      return FALSE;
    }

    $entity = entity_load_single($this->entity_type, $id);
    return $this->checkBundle($entity) ? $entity : FALSE;
  }

  /**
   * {@inheritdoc}
   */
  public function configForm($form, &$form_state) {
    $form = parent::configForm($form, $form_state);

    $form['settings']['fk_col'] = array(
      '#type' => 'textfield',
      '#title' => t('Foreign Key Column'),
      '#description' => t('the column referring this to the base entity.'),
      '#default_value' => !empty($this->settings['fk_col']) ? $this->settings['fk_col'] : '',
      '#required' => TRUE,
    );
    $form['settings']['pk_col'] = array(
      '#type' => 'textfield',
      '#title' => t('Primary Key Column'),
      '#description' => t('the column referring this to the base entity.'),
      '#default_value' => !empty($this->settings['pk_col']) ? $this->settings['pk_col'] : '',
      '#required' => TRUE,
    );

    return $form;
  }
}

Hey @rlmumford - thanks for the response and sorry to delay so long before getting back to this. The class name duplication that you pointed out, I accidentally pasted the wrong code in here, and so that is not a problem. In the interim, I also figured out how to get a new file added to a git patch, so, I moved past that step as well. I still have some bugs to work through on this, but will be following back. Thanks again.

Attached patch adds include files and necessary adjustments to the .info and .inc files to enable for all installs. This is a very simple implementation that assumes the table to be joined:

1. Has a field that points to the Entity_ID field of the current flexiform base entity, described as "Foreign Key" in config form.
2. Has it's own unique identifier field, described as "Primarey Key" in config form.

Potential application of this with Data module to provide editing.