Fix errors when mentioning others in Ponder

Summary: Fixes T9552. We need to set a questionID and the question object (for policy) when initializing a new Answer.

Test Plan: Write an answer that mentions another user.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T9552

Differential Revision: https://secure.phabricator.com/D14263

src/applications/ponder/controller/PonderAnswerSaveController.php

@@ -32,7 +32,7 @@ final class PonderAnswerSaveController extends PonderController {
       return id(new AphrontDialogResponse())->setDialog($dialog);
     }
 
-    $answer = PonderAnswer::initializeNewAnswer($viewer);
+    $answer = PonderAnswer::initializeNewAnswer($viewer, $question);
 
     // Question Editor
 

src/applications/ponder/storage/PonderAnswer.php

@@ -26,15 +26,18 @@ final class PonderAnswer extends PonderDAO
 
   private $userVotes = array();
 
-  public static function initializeNewAnswer(PhabricatorUser $actor) {
+  public static function initializeNewAnswer(
+    PhabricatorUser $actor,
+    PonderQuestion $question) {
     $app = id(new PhabricatorApplicationQuery())
       ->setViewer($actor)
       ->withClasses(array('PhabricatorPonderApplication'))
       ->executeOne();
 
     return id(new PonderAnswer())
-      ->setQuestionID(0)
+      ->setQuestionID($question->getID())
       ->setContent('')
+      ->attachQuestion($question)
       ->setAuthorPHID($actor->getPHID())
       ->setVoteCount(0)
       ->setStatus(PonderAnswerStatus::ANSWER_STATUS_VISIBLE);