Extbase Optional Relation Property

/***********************************************
 *
 * Change Setter in DomainObject
 *
 **********************************************/





/**
 * Sets the Related Property
 *
 * @param Tx_Myext_Domain_Model_RelatedObject $relatedObject
 * @return Tx_Myext_Domain_Model_ParentObject
 */
public function setRelatedObject( $relatedObject = NULL ) {
    // reset the object if something other then a valid object is passed
  if ( ! $relatedObject instanceof Tx_Myext_Domain_Model_RelatedObject ) {
    $relatedObject = NULL;
  }
  $this->relatedObject = $relatedObject;
  return $this;
}





/***********************************************
 *
 * custom Converter
 * To enable this in your extension, add the following to you ext_localconf.php
 * Tx_Extbase_Utility_Extension::registerTypeConverter( 'Tx_Myext_Property_TypeConverter_PersistentObjectConverter' );
 *
 **********************************************/


/**
 * allows for empty values - in this case it will return NULL
 *
 * To enable this in your extension, add the following to you ext_localconf.php
 *  // Register type converters
 * Tx_Extbase_Utility_Extension::registerTypeConverter( 'Tx_Myext_Property_TypeConverter_PersistentObjectConverter' );
 */
class Tx_Myext_Property_TypeConverter_PersistentObjectConverter extends Tx_Extbase_Property_TypeConverter_PersistentObjectConverter {

  /**
   * @var integer
   */
  protected $priority = 2;


  /**
   * We can only convert if the $targetType is either tagged with entity or value object.
   * Empty strings CAN NOT be converted BUT will return NULL
   *
   * @param mixed $source
   * @param string $targetType
   * @return boolean
   */
  public function canConvertFrom($source, $targetType) {
    if ( is_array( $source ) && isset( $source['__identity'] ) && 1 === count( $source ) && 0 >= intval( $source['__identity'] ) ) {
      return TRUE;
    }
    elseif ( '' === $source || -1 === intval( $source ) || 0 === intval( $source ) ) {
      return TRUE;
    } else {
      return parent::canConvertFrom( $source, $targetType );
    }
  }

  /**
   * Convert an object from $source to an entity or a value object.
   * Empty strings CAN NOT be converted BUT will return NULL
   *
   * @param mixed $source
   * @param string $targetType
   * @param array $convertedChildProperties
   * @param Tx_Extbase_Property_PropertyMappingConfigurationInterface $configuration
   * @return object the target type
   */
  public function convertFrom($source, $targetType, array $convertedChildProperties = array(), Tx_Extbase_Property_PropertyMappingConfigurationInterface $configuration = NULL) {
    if ( is_array( $source ) && isset( $source['__identity'] ) && 1 === count( $source ) && 0 >= intval( $source['__identity'] ) ) {
      return 0;
    }
    elseif ( '' === $source || -1 === intval( $source ) || 0 === intval( $source ) ) {
      return 0;
    } else {
      return parent::convertFrom( $source, $targetType, $convertedChildProperties, $configuration );
    }
  }
}