/**
  * This function performs the validation work for complex object models.
  *
  * In addition to checking the current object, all related objects will
  * also be validated.  If all pass then <code>true</code> is returned; otherwise
  * an aggregated array of ValidationFailed objects will be returned.
  *
  * @param array $columns Array of column names to validate.
  * @return mixed <code>true</code> if all validations pass; array of <code>ValidationFailed</code> objects otherwise.
  */
 protected function doValidate($columns = null)
 {
     if (!$this->alreadyInValidation) {
         $this->alreadyInValidation = true;
         $retval = null;
         $failureMap = array();
         // We call the validate method on the following object(s) if they
         // were passed to this object by their corresponding set
         // method.  This object relates to these object(s) by a
         // foreign key reference.
         if ($this->aUser !== null) {
             if (!$this->aUser->validate($columns)) {
                 $failureMap = array_merge($failureMap, $this->aUser->getValidationFailures());
             }
         }
         if ($this->aSkill !== null) {
             if (!$this->aSkill->validate($columns)) {
                 $failureMap = array_merge($failureMap, $this->aSkill->getValidationFailures());
             }
         }
         if (($retval = UserSkillPeer::doValidate($this, $columns)) !== true) {
             $failureMap = array_merge($failureMap, $retval);
         }
         $this->alreadyInValidation = false;
     }
     return !empty($failureMap) ? $failureMap : true;
 }