Trying to get property of non-object in QuizQuestion->getNodeProperties() line 194

Hi,

Using Quiz module and its Multichoice extension in a project in combination with the Flag module caused some Notices to appear.

These notices are coming from the getNodeProperties() method of the QuizQuestion class because the $row is actually FALSE instead of object

  /**
   * Getter function returning properties to be loaded when the node is loaded.
   *
   * @see load hook in quiz_question.module (quiz_question_load)
   *
   * @return array
   */
  public function getNodeProperties() {
    if (isset($this->nodeProperties)) {
      return $this->nodeProperties;
    }
    $result = db_query('SELECT *
      FROM {quiz_question_properties}
      WHERE nid = :nid AND vid = :vid', array(':nid' => $this->node->nid, ':vid' => $this->node->vid));
    $row = $result->fetch();
    $props['max_score'] = $row->max_score;
    $props['feedback']['value'] = $row->feedback;
    $props['feedback']['format'] = $row->feedback_format;
    $props['is_quiz_question'] = TRUE;
    $this->nodeProperties = $props;
    return $props;
  }

The specific lines are:

    $props['max_score'] = $row->max_score;
    $props['feedback']['value'] = $row->feedback;
    $props['feedback']['format'] = $row->feedback_format;

The reason for $row being FALSE is that the getNodeProperties() is called too early because of the Flag module. The flag module hooks on field_attach_insert, which is invoked on node_save.
When the Flag module hooks there it executes series of function ending at some point to entity_load() and this one is then ending to call getNodeProperties() before the node is actually saved. Which means there is no record in the quiz_question_properties table and therefore the $row is FALSE.

It will be really hard to make changes on the Flag module to fix their issue as it will require changes in some of their core functions, therefore I decided to make a quick patch for the Quiz module to just prevent the notices in cases like this.

It is coming in the next comment.

Regards,
Lachezar