Move Differential commit message rendering to dedicated classes

Summary:
Ref T11114. This probably still has some bugs, but survives basic sanity checks.

Continue pulling commit message logic out of CustomField so we can reduce the amount of responsibility/bloat in the classtree and send more code through EditEngine.

Test Plan:
  - Called `differential.getcommitmessage` via API console for various revisions/parameters (edit and create mode, with and without fields, with and without revisions).
  - Used `--create`, `--edit` and `--update` modes of `arc diff` from the CLI.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11114

Differential Revision: https://secure.phabricator.com/D17066

src/__phutil_library_map__.php

@@ -385,6 +385,7 @@ phutil_register_library_map(array(
     'DifferentialCloseConduitAPIMethod' => 'applications/differential/conduit/DifferentialCloseConduitAPIMethod.php',
     'DifferentialCommentPreviewController' => 'applications/differential/controller/DifferentialCommentPreviewController.php',
     'DifferentialCommentSaveController' => 'applications/differential/controller/DifferentialCommentSaveController.php',
+    'DifferentialCommitMessageCustomField' => 'applications/differential/field/DifferentialCommitMessageCustomField.php',
     'DifferentialCommitMessageField' => 'applications/differential/field/DifferentialCommitMessageField.php',
     'DifferentialCommitMessageParser' => 'applications/differential/parser/DifferentialCommitMessageParser.php',
     'DifferentialCommitMessageParserTestCase' => 'applications/differential/parser/__tests__/DifferentialCommitMessageParserTestCase.php',
@@ -4996,10 +4997,10 @@ phutil_register_library_map(array(
     'DifferentialAffectedPath' => 'DifferentialDAO',
     'DifferentialApplyPatchField' => 'DifferentialCustomField',
     'DifferentialAsanaRepresentationField' => 'DifferentialCustomField',
-    'DifferentialAuditorsCommitMessageField' => 'DifferentialCommitMessageField',
+    'DifferentialAuditorsCommitMessageField' => 'DifferentialCommitMessageCustomField',
     'DifferentialAuditorsField' => 'DifferentialStoredCustomField',
     'DifferentialAuthorField' => 'DifferentialCustomField',
-    'DifferentialBlameRevisionCommitMessageField' => 'DifferentialCommitMessageField',
+    'DifferentialBlameRevisionCommitMessageField' => 'DifferentialCommitMessageCustomField',
     'DifferentialBlameRevisionField' => 'DifferentialStoredCustomField',
     'DifferentialBlockHeraldAction' => 'HeraldAction',
     'DifferentialBlockingReviewerDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
@@ -5031,6 +5032,7 @@ phutil_register_library_map(array(
     'DifferentialCloseConduitAPIMethod' => 'DifferentialConduitAPIMethod',
     'DifferentialCommentPreviewController' => 'DifferentialController',
     'DifferentialCommentSaveController' => 'DifferentialController',
+    'DifferentialCommitMessageCustomField' => 'DifferentialCommitMessageField',
     'DifferentialCommitMessageField' => 'Phobject',
     'DifferentialCommitMessageParser' => 'Phobject',
     'DifferentialCommitMessageParserTestCase' => 'PhabricatorTestCase',
@@ -5125,7 +5127,7 @@ phutil_register_library_map(array(
     'DifferentialInlineCommentMailView' => 'DifferentialMailView',
     'DifferentialInlineCommentPreviewController' => 'PhabricatorInlineCommentPreviewController',
     'DifferentialInlineCommentQuery' => 'PhabricatorOffsetPagedQuery',
-    'DifferentialJIRAIssuesCommitMessageField' => 'DifferentialCommitMessageField',
+    'DifferentialJIRAIssuesCommitMessageField' => 'DifferentialCommitMessageCustomField',
     'DifferentialJIRAIssuesField' => 'DifferentialStoredCustomField',
     'DifferentialLandingActionMenuEventListener' => 'PhabricatorEventListener',
     'DifferentialLandingStrategy' => 'Phobject',
@@ -5158,7 +5160,7 @@ phutil_register_library_map(array(
     'DifferentialResponsibleDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
     'DifferentialResponsibleUserDatasource' => 'PhabricatorTypeaheadCompositeDatasource',
     'DifferentialResponsibleViewerFunctionDatasource' => 'PhabricatorTypeaheadDatasource',
-    'DifferentialRevertPlanCommitMessageField' => 'DifferentialCommitMessageField',
+    'DifferentialRevertPlanCommitMessageField' => 'DifferentialCommitMessageCustomField',
     'DifferentialRevertPlanField' => 'DifferentialStoredCustomField',
     'DifferentialReviewedByCommitMessageField' => 'DifferentialCommitMessageField',
     'DifferentialReviewedByField' => 'DifferentialCoreCustomField',

src/applications/differential/conduit/DifferentialGetCommitMessageConduitAPIMethod.php

@@ -47,94 +47,71 @@ final class DifferentialGetCommitMessageConduitAPIMethod
       }
     } else {
       $revision = DifferentialRevision::initializeNewRevision($viewer);
-      $revision->attachReviewerStatus(array());
-      $revision->attachActiveDiff(null);
     }
 
-    $is_edit = $request->getValue('edit');
-    $is_create = ($is_edit == 'create');
+    $edit_mode = $request->getValue('edit');
+    $is_create = ($edit_mode == 'create');
+    $is_edit = ($edit_mode && !$is_create);
 
-    $field_list = PhabricatorCustomField::getObjectFields(
-      $revision,
-      ($is_edit
-        ? DifferentialCustomField::ROLE_COMMITMESSAGEEDIT
-        : DifferentialCustomField::ROLE_COMMITMESSAGE));
+    $field_list = DifferentialCommitMessageField::newEnabledFields($viewer);
 
-    $field_list
-      ->setViewer($viewer)
-      ->readFieldsFromStorage($revision);
-
-    $field_map = mpull($field_list->getFields(), null, 'getFieldKeyForConduit');
+    $custom_storage = $this->loadCustomFieldStorage($viewer, $revision);
+    foreach ($field_list as $field) {
+      $field->setCustomFieldStorage($custom_storage);
+    }
 
+    // If we're editing the message, remove fields like "Conflicts" and
+    // "git-svn-id" which should not be presented to the user for editing.
     if ($is_edit) {
-      $fields = $request->getValue('fields', array());
-      foreach ($fields as $field => $value) {
-        $custom_field = idx($field_map, $field);
-        if (!$custom_field) {
-          // Just ignore this, these workflows don't make strong distictions
-          // about field editability on the client side.
-          continue;
-        }
-        if ($is_create ||
-            $custom_field->shouldOverwriteWhenCommitMessageIsEdited()) {
-          $custom_field->readValueFromCommitMessage($value);
+      foreach ($field_list as $field_key => $field) {
+        if (!$field->isFieldEditable()) {
+          unset($field_list[$field_key]);
         }
       }
     }
 
-    $phids = array();
-    foreach ($field_list->getFields() as $key => $field) {
-      $field_phids = $field->getRequiredHandlePHIDsForCommitMessage();
-      if (!is_array($field_phids)) {
-        throw new Exception(
-          pht(
-            'Custom field "%s" was expected to return an array of handle '.
-            'PHIDs required for commit message rendering, but returned "%s" '.
-            'instead.',
-            $field->getFieldKey(),
-            gettype($field_phids)));
+    $overrides = $request->getValue('fields', array());
+
+    $value_map = array();
+    foreach ($field_list as $field_key => $field) {
+      if (array_key_exists($field_key, $overrides)) {
+        $field_value = $overrides[$field_key];
+      } else {
+        $field_value = $field->readFieldValueFromObject($revision);
       }
-      $phids[$key] = $field_phids;
+
+      // We're calling this method on the value no matter where we got it
+      // from, so we hit the same validation logic for values which came over
+      // the wire and which we generated.
+      $field_value = $field->readFieldValueFromConduit($field_value);
+
+      $value_map[$field_key] = $field_value;
     }
 
-    $all_phids = array_mergev($phids);
-    if ($all_phids) {
-      $all_handles = id(new PhabricatorHandleQuery())
-        ->setViewer($viewer)
-        ->withPHIDs($all_phids)
-        ->execute();
-    } else {
-      $all_handles = array();
-    }
-
-    $key_title = id(new DifferentialTitleField())->getFieldKey();
-    $default_title = DifferentialTitleField::getDefaultTitle();
+    $key_title = DifferentialTitleCommitMessageField::FIELDKEY;
 
     $commit_message = array();
-    foreach ($field_list->getFields() as $key => $field) {
-      $handles = array_select_keys($all_handles, $phids[$key]);
+    foreach ($field_list as $field_key => $field) {
+      $label = $field->getFieldName();
+      $wire_value = $value_map[$field_key];
+      $value = $field->renderFieldValue($wire_value);
 
-      $label = $field->renderCommitMessageLabel();
-      $value = $field->renderCommitMessageValue($handles);
+      $is_template = ($is_edit && $field->isTemplateField());
 
       if (!is_string($value) && !is_null($value)) {
         throw new Exception(
           pht(
-            'Custom field "%s" was expected to render a string or null value, '.
-            'but rendered a "%s" instead.',
+            'Commit message field "%s" was expected to render a string or '.
+            'null value, but rendered a "%s" instead.',
             $field->getFieldKey(),
             gettype($value)));
       }
 
-      $is_title = ($key == $key_title);
+      $is_title = ($field_key == $key_title);
 
       if (!strlen($value)) {
-        if ($is_title) {
-          $commit_message[] = $default_title;
-        } else {
-          if ($is_edit && $field->shouldAppearInCommitMessageTemplate()) {
-            $commit_message[] = $label.': ';
-          }
+        if ($is_template) {
+          $commit_message[] = $label.': ';
         }
       } else {
         if ($is_title) {
@@ -153,46 +130,31 @@ final class DifferentialGetCommitMessageConduitAPIMethod
       }
     }
 
-    if ($is_edit) {
-      $tip = $this->getProTip($field_list);
-      if ($tip !== null) {
-        $commit_message[] = "\n".$tip;
+    return implode("\n\n", $commit_message);
+  }
+
+  private function loadCustomFieldStorage(
+    PhabricatorUser $viewer,
+    DifferentialRevision $revision) {
+    $custom_field_list = PhabricatorCustomField::getObjectFields(
+      $revision,
+      DifferentialCustomField::ROLE_COMMITMESSAGE);
+    $custom_field_list
+      ->setViewer($viewer)
+      ->readFieldsFromStorage($revision);
+
+    $custom_field_map = array();
+    foreach ($custom_field_list->getFields() as $custom_field) {
+      if (!$custom_field->shouldUseStorage()) {
+        continue;
       }
+      $custom_field_key = $custom_field->getFieldKey();
+      $custom_field_value = $custom_field->getValueForStorage();
+      $custom_field_map[$custom_field_key] = $custom_field_value;
     }
 
-    $commit_message = implode("\n\n", $commit_message);
-
-    return $commit_message;
+    return $custom_field_map;
   }
 
-  private function getProTip() {
-    // Any field can provide tips, whether it normally appears on commit
-    // messages or not.
-    $field_list = PhabricatorCustomField::getObjectFields(
-      new DifferentialRevision(),
-      PhabricatorCustomField::ROLE_DEFAULT);
-
-    $tips = array();
-    foreach ($field_list->getFields() as $key => $field) {
-      $tips[] = $field->getProTips();
-    }
-    $tips = array_mergev($tips);
-
-    if (!$tips) {
-      return null;
-    }
-
-    shuffle($tips);
-
-    $tip = pht('Tip: %s', head($tips));
-    $tip = wordwrap($tip, 78, "\n", true);
-
-    $lines = explode("\n", $tip);
-    foreach ($lines as $key => $line) {
-      $lines[$key] = '# '.$line;
-    }
-
-    return implode("\n", $lines);
-  }
 
 }

src/applications/differential/field/DifferentialAuditorsCommitMessageField.php

@@ -1,7 +1,7 @@
 <?php
 
 final class DifferentialAuditorsCommitMessageField
-  extends DifferentialCommitMessageField {
+  extends DifferentialCommitMessageCustomField {
 
   const FIELDKEY = 'phabricator:auditors';
 
@@ -18,4 +18,20 @@ final class DifferentialAuditorsCommitMessageField
       ));
   }
 
+  public function getCustomFieldKey() {
+    return 'phabricator:auditors';
+  }
+
+  public function readFieldValueFromConduit($value) {
+    return $this->readStringListFieldValueFromConduit($value);
+  }
+
+  public function renderFieldValue($value) {
+    return $this->renderHandleList($value);
+  }
+
+  protected function readFieldValueFromCustomFieldStorage($value) {
+    return $this->readJSONFieldValueFromCustomFieldStorage($value, array());
+  }
+
 }

src/applications/differential/field/DifferentialBlameRevisionCommitMessageField.php

@@ -1,7 +1,7 @@
 <?php
 
 final class DifferentialBlameRevisionCommitMessageField
-  extends DifferentialCommitMessageField {
+  extends DifferentialCommitMessageCustomField {
 
   const FIELDKEY = 'blameRevision';
 
@@ -15,8 +15,8 @@ final class DifferentialBlameRevisionCommitMessageField
     );
   }
 
-  public function isFieldEnabled() {
-    return $this->isCustomFieldEnabled('phabricator:blame-revision');
+  public function getCustomFieldKey() {
+    return 'phabricator:blame-revision';
   }
 
 }

src/applications/differential/field/DifferentialCommitMessageCustomField.php

@@ -0,0 +1,63 @@
+<?php
+
+abstract class DifferentialCommitMessageCustomField
+  extends DifferentialCommitMessageField {
+
+  abstract public function getCustomFieldKey();
+
+  public function getFieldOrder() {
+    $custom_key = $this->getCustomFieldKey();
+    return 100000 + $this->getCustomFieldOrder($custom_key);
+  }
+
+  public function isFieldEnabled() {
+    $custom_key = $this->getCustomFieldKey();
+    return $this->isCustomFieldEnabled($custom_key);
+  }
+
+  public function readFieldValueFromObject(DifferentialRevision $revision) {
+    $custom_key = $this->getCustomFieldKey();
+    $value = $this->readCustomFieldValue($revision, $custom_key);
+    return $value;
+  }
+
+  protected function readFieldValueFromCustomFieldStorage($value) {
+    return $value;
+  }
+
+  protected function readJSONFieldValueFromCustomFieldStorage(
+    $value,
+    $default) {
+    try {
+      return phutil_json_decode($value);
+    } catch (PhutilJSONParserException $ex) {
+      return $default;
+    }
+  }
+
+  protected function readCustomFieldValue(
+    DifferentialRevision $revision,
+    $key) {
+    $value = idx($this->getCustomFieldStorage(), $key);
+    return $this->readFieldValueFromCustomFieldStorage($value);
+  }
+
+  protected function getCustomFieldOrder($key) {
+    $field_list = PhabricatorCustomField::getObjectFields(
+      new DifferentialRevision(),
+      DifferentialCustomField::ROLE_COMMITMESSAGE);
+
+    $fields = $field_list->getFields();
+
+    $idx = 0;
+    foreach ($fields as $field_key => $value) {
+      if ($key === $field_key) {
+        return $idx;
+      }
+      $idx++;
+    }
+
+    return $idx;
+  }
+
+}

src/applications/differential/field/DifferentialCommitMessageField.php

@@ -4,6 +4,7 @@ abstract class DifferentialCommitMessageField
   extends Phobject {
 
   private $viewer;
+  private $customFieldStorage;
 
   final public function setViewer(PhabricatorUser $viewer) {
     $this->viewer = $viewer;
@@ -14,7 +15,17 @@ abstract class DifferentialCommitMessageField
     return $this->viewer;
   }
 
+  final public function setCustomFieldStorage(array $custom_field_storage) {
+    $this->customFieldStorage = $custom_field_storage;
+    return $this;
+  }
+
+  final public function getCustomFieldStorage() {
+    return $this->customFieldStorage;
+  }
+
   abstract public function getFieldName();
+  abstract public function getFieldOrder();
 
   public function isFieldEnabled() {
     return true;
@@ -32,6 +43,30 @@ abstract class DifferentialCommitMessageField
     return $value;
   }
 
+  public function isFieldEditable() {
+    return true;
+  }
+
+  public function isTemplateField() {
+    return true;
+  }
+
+  public function readFieldValueFromConduit($value) {
+    return $this->readStringFieldValueFromConduit($value);
+  }
+
+  public function readFieldValueFromObject(DifferentialRevision $revision) {
+    return null;
+  }
+
+  public function renderFieldValue($value) {
+    if (!strlen($value)) {
+      return null;
+    }
+
+    return $value;
+  }
+
   final public function getCommitMessageFieldKey() {
     return $this->getPhobjectClassConstant('FIELDKEY', 64);
   }
@@ -55,6 +90,7 @@ abstract class DifferentialCommitMessageField
     return id(new PhutilClassMapQuery())
       ->setAncestorClass(__CLASS__)
       ->setUniqueMethod('getCommitMessageFieldKey')
+      ->setSortMethod('getFieldOrder')
       ->execute();
   }
 
@@ -80,6 +116,62 @@ abstract class DifferentialCommitMessageField
       ->execute();
   }
 
+  protected function renderHandleList(array $phids, array $suffixes = array()) {
+    if (!$phids) {
+      return null;
+    }
+
+    $handles = $this->getViewer()->loadHandles($phids);
+
+    $out = array();
+    foreach ($handles as $handle) {
+      $phid = $handle->getPHID();
+
+      if ($handle->getPolicyFiltered()) {
+        $token = $phid;
+      } else if ($handle->isComplete()) {
+        $token = $handle->getCommandLineObjectName();
+      }
+
+      $suffix = idx($suffixes, $phid);
+      $token = $token.$suffix;
+
+      $out[] = $token;
+    }
+
+    return implode(', ', $out);
+  }
+
+  protected function readStringFieldValueFromConduit($value) {
+    if ($value === null) {
+      return $value;
+    }
+
+    if (!is_string($value)) {
+      throw new Exception(
+        pht(
+          'Field "%s" expects a string value, but received a value of type '.
+          '"%s".',
+          $this->getCommitMessageFieldKey(),
+          gettype($value)));
+    }
+
+    return $value;
+  }
+
+  protected function readStringListFieldValueFromConduit($value) {
+    if (!is_array($value)) {
+      throw new Exception(
+        pht(
+          'Field "%s" expects a list of strings, but received a value of type '.
+          '"%s".',
+          $this->getCommitMessageFieldKey(),
+          gettype($value)));
+    }
+
+    return $value;
+  }
+
   protected function isCustomFieldEnabled($key) {
     $field_list = PhabricatorCustomField::getObjectFields(
       new DifferentialRevision(),

src/applications/differential/field/DifferentialConflictsCommitMessageField.php

@@ -9,4 +9,12 @@ final class DifferentialConflictsCommitMessageField
     return pht('Conflicts');
   }
 
+  public function getFieldOrder() {
+    return 900000;
+  }
+
+  public function isFieldEditable() {
+    return false;
+  }
+
 }

src/applications/differential/field/DifferentialGitSVNIDCommitMessageField.php

@@ -9,4 +9,12 @@ final class DifferentialGitSVNIDCommitMessageField
     return pht('git-svn-id');
   }
 
+  public function getFieldOrder() {
+    return 900001;
+  }
+
+  public function isFieldEditable() {
+    return false;
+  }
+
 }

src/applications/differential/field/DifferentialJIRAIssuesCommitMessageField.php

@@ -1,7 +1,7 @@
 <?php
 
 final class DifferentialJIRAIssuesCommitMessageField
-  extends DifferentialCommitMessageField {
+  extends DifferentialCommitMessageCustomField {
 
   const FIELDKEY = 'jira.issues';
 
@@ -16,12 +16,28 @@ final class DifferentialJIRAIssuesCommitMessageField
     );
   }
 
+  public function getCustomFieldKey() {
+    return 'phabricator:jira-issues';
+  }
+
   public function parseFieldValue($value) {
     return preg_split('/[\s,]+/', $value, $limit = -1, PREG_SPLIT_NO_EMPTY);
   }
 
-  public function isFieldEnabled() {
-    return (bool)PhabricatorJIRAAuthProvider::getJIRAProvider();
+  protected function readFieldValueFromCustomFieldStorage($value) {
+    return $this->readJSONFieldValueFromCustomFieldStorage($value, array());
+  }
+
+  public function readFieldValueFromConduit($value) {
+    return $this->readStringListFieldValueFromConduit($value);
+  }
+
+  public function renderFieldValue($value) {
+    if (!$value) {
+      return null;
+    }
+
+    return implode(', ', $value);
   }
 
 }

src/applications/differential/field/DifferentialRevertPlanCommitMessageField.php

@@ -1,7 +1,7 @@
 <?php
 
 final class DifferentialRevertPlanCommitMessageField
-  extends DifferentialCommitMessageField {
+  extends DifferentialCommitMessageCustomField {
 
   const FIELDKEY = 'revertPlan';
 
@@ -9,8 +9,8 @@ final class DifferentialRevertPlanCommitMessageField
     return pht('Revert Plan');
   }
 
-  public function isFieldEnabled() {
-    return $this->isCustomFieldEnabled('phabricator:revert-plan');
+  public function getCustomFieldKey() {
+    return 'phabricator:revert-plan';
   }
 
 }

src/applications/differential/field/DifferentialReviewedByCommitMessageField.php

@@ -9,6 +9,10 @@ final class DifferentialReviewedByCommitMessageField
     return pht('Reviewed By');
   }
 
+  public function getFieldOrder() {
+    return 5000;
+  }
+
   public function parseFieldValue($value) {
     return $this->parseObjectList(
       $value,
@@ -19,4 +23,34 @@ final class DifferentialReviewedByCommitMessageField
       $allow_partial = true);
   }
 
+  public function isFieldEditable() {
+    return false;
+  }
+
+  public function readFieldValueFromObject(DifferentialRevision $revision) {
+    if (!$revision->getPHID()) {
+      return array();
+    }
+
+    $phids = array();
+    foreach ($revision->getReviewerStatus() as $reviewer) {
+      switch ($reviewer->getStatus()) {
+        case DifferentialReviewerStatus::STATUS_ACCEPTED:
+        case DifferentialReviewerStatus::STATUS_ACCEPTED_OLDER:
+          $phids[] = $reviewer->getReviewerPHID();
+          break;
+      }
+    }
+
+    return $phids;
+  }
+
+  public function readFieldValueFromConduit($value) {
+    return $this->readStringListFieldValueFromConduit($value);
+  }
+
+  public function renderFieldValue($value) {
+    return $this->renderHandleList($value);
+  }
+
 }

src/applications/differential/field/DifferentialReviewersCommitMessageField.php

@@ -9,6 +9,10 @@ final class DifferentialReviewersCommitMessageField
     return pht('Reviewers');
   }
 
+  public function getFieldOrder() {
+    return 4000;
+  }
+
   public function getFieldAliases() {
     return array(
       'Reviewer',
@@ -29,6 +33,50 @@ final class DifferentialReviewersCommitMessageField
     return $this->flattenReviewers($results);
   }
 
+  public function readFieldValueFromConduit($value) {
+    return $this->readStringListFieldValueFromConduit($value);
+  }
+
+  public function readFieldValueFromObject(DifferentialRevision $revision) {
+    if (!$revision->getPHID()) {
+      return array();
+    }
+
+    $status_blocking = DifferentialReviewerStatus::STATUS_BLOCKING;
+
+    $results = array();
+    foreach ($revision->getReviewerStatus() as $reviewer) {
+      if ($reviewer->getStatus() == $status_blocking) {
+        $suffixes = array('!' => '!');
+      } else {
+        $suffixes = array();
+      }
+
+      $results[] = array(
+        'phid' => $reviewer->getReviewerPHID(),
+        'suffixes' => $suffixes,
+      );
+    }
+
+    return $this->flattenReviewers($results);
+  }
+
+  public function renderFieldValue($value) {
+    $value = $this->inflateReviewers($value);
+
+    $phid_list = array();
+    $suffix_map = array();
+    foreach ($value as $reviewer) {
+      $phid = $reviewer['phid'];
+      $phid_list[] = $phid;
+      if (isset($reviewer['suffixes']['!'])) {
+        $suffix_map[$phid] = '!';
+      }
+    }
+
+    return $this->renderHandleList($phid_list, $suffix_map);
+  }
+
   private function flattenReviewers(array $values) {
     // NOTE: For now, `arc` relies on this field returning only scalars, so we
     // need to reduce the results into scalars. See T10981.

src/applications/differential/field/DifferentialRevisionIDCommitMessageField.php

@@ -9,6 +9,14 @@ final class DifferentialRevisionIDCommitMessageField
     return pht('Differential Revision');
   }
 
+  public function getFieldOrder() {
+    return 200000;
+  }
+
+  public function isTemplateField() {
+    return false;
+  }
+
   public function parseFieldValue($value) {
     // If the value is just "D123" or similar, parse the ID from it directly.
     $value = trim($value);
@@ -49,4 +57,23 @@ final class DifferentialRevisionIDCommitMessageField
     return null;
   }
 
+  public function readFieldValueFromObject(DifferentialRevision $revision) {
+    return $revision->getID();
+  }
+
+  public function readFieldValueFromConduit($value) {
+    if (is_int($value)) {
+      $value = (string)$value;
+    }
+    return $this->readStringFieldValueFromConduit($value);
+  }
+
+  public function renderFieldValue($value) {
+    if (!strlen($value)) {
+      return null;
+    }
+
+    return PhabricatorEnv::getProductionURI('/D'.$value);
+  }
+
 }

src/applications/differential/field/DifferentialSubscribersCommitMessageField.php

@@ -9,6 +9,10 @@ final class DifferentialSubscribersCommitMessageField
     return pht('Subscribers');
   }
 
+  public function getFieldOrder() {
+    return 6000;
+  }
+
   public function getFieldAliases() {
     return array(
       'CC',
@@ -27,4 +31,21 @@ final class DifferentialSubscribersCommitMessageField
       ));
   }
 
+  public function readFieldValueFromObject(DifferentialRevision $revision) {
+    if (!$revision->getPHID()) {
+      return array();
+    }
+
+    return PhabricatorSubscribersQuery::loadSubscribersForPHID(
+      $revision->getPHID());
+  }
+
+  public function readFieldValueFromConduit($value) {
+    return $this->readStringListFieldValueFromConduit($value);
+  }
+
+  public function renderFieldValue($value) {
+    return $this->renderHandleList($value);
+  }
+
 }

src/applications/differential/field/DifferentialSummaryCommitMessageField.php

@@ -9,4 +9,12 @@ final class DifferentialSummaryCommitMessageField
     return pht('Summary');
   }
 
+  public function getFieldOrder() {
+    return 2000;
+  }
+
+  public function readFieldValueFromObject(DifferentialRevision $revision) {
+    return $revision->getSummary();
+  }
+
 }

src/applications/differential/field/DifferentialTagsCommitMessageField.php

@@ -9,6 +9,10 @@ final class DifferentialTagsCommitMessageField
     return pht('Tags');
   }
 
+  public function getFieldOrder() {
+    return 7000;
+  }
+
   public function getFieldAliases() {
     return array(
       'Tag',
@@ -17,6 +21,10 @@ final class DifferentialTagsCommitMessageField
     );
   }
 
+  public function isTemplateField() {
+    return false;
+  }
+
   public function parseFieldValue($value) {
     return $this->parseObjectList(
       $value,
@@ -25,4 +33,26 @@ final class DifferentialTagsCommitMessageField
       ));
   }
 
+  public function readFieldValueFromObject(DifferentialRevision $revision) {
+    if (!$revision->getPHID()) {
+      return array();
+    }
+
+    $projects = PhabricatorEdgeQuery::loadDestinationPHIDs(
+      $revision->getPHID(),
+      PhabricatorProjectObjectHasProjectEdgeType::EDGECONST);
+    $projects = array_reverse($projects);
+
+    return $projects;
+  }
+
+  public function readFieldValueFromConduit($value) {
+    return $this->readStringListFieldValueFromConduit($value);
+  }
+
+  public function renderFieldValue($value) {
+    return $this->renderHandleList($value);
+  }
+
+
 }

src/applications/differential/field/DifferentialTasksCommitMessageField.php

@@ -9,6 +9,10 @@ final class DifferentialTasksCommitMessageField
     return pht('Maniphest Tasks');
   }
 
+  public function getFieldOrder() {
+    return 8000;
+  }
+
   public function getFieldAliases() {
     return array(
       'Task',
@@ -17,6 +21,10 @@ final class DifferentialTasksCommitMessageField
     );
   }
 
+  public function isTemplateField() {
+    return false;
+  }
+
   public function parseFieldValue($value) {
     return $this->parseObjectList(
       $value,
@@ -25,4 +33,25 @@ final class DifferentialTasksCommitMessageField
       ));
   }
 
+  public function readFieldValueFromObject(DifferentialRevision $revision) {
+    if (!$revision->getPHID()) {
+      return array();
+    }
+
+    $projects = PhabricatorEdgeQuery::loadDestinationPHIDs(
+      $revision->getPHID(),
+      DifferentialRevisionHasTaskEdgeType::EDGECONST);
+    $projects = array_reverse($projects);
+
+    return $projects;
+  }
+
+  public function readFieldValueFromConduit($value) {
+    return $this->readStringListFieldValueFromConduit($value);
+  }
+
+  public function renderFieldValue($value) {
+    return $this->renderHandleList($value);
+  }
+
 }

src/applications/differential/field/DifferentialTestPlanCommitMessageField.php

@@ -9,6 +9,10 @@ final class DifferentialTestPlanCommitMessageField
     return pht('Test Plan');
   }
 
+  public function getFieldOrder() {
+    return 3000;
+  }
+
   public function getFieldAliases() {
     return array(
       'Testplan',
@@ -33,4 +37,8 @@ final class DifferentialTestPlanCommitMessageField
     }
   }
 
+  public function readFieldValueFromObject(DifferentialRevision $revision) {
+    return $revision->getTestPlan();
+  }
+
 }

src/applications/differential/field/DifferentialTitleCommitMessageField.php

@@ -9,6 +9,10 @@ final class DifferentialTitleCommitMessageField
     return pht('Title');
   }
 
+  public function getFieldOrder() {
+    return 1000;
+  }
+
   public static function getDefaultTitle() {
     return pht('<<Replace this line with your revision title>');
   }
@@ -33,4 +37,14 @@ final class DifferentialTitleCommitMessageField
     }
   }
 
+  public function readFieldValueFromObject(DifferentialRevision $revision) {
+    $value = $revision->getTitle();
+
+    if (!strlen($value)) {
+      return self::getDefaultTitle();
+    }
+
+    return $value;
+  }
+
 }

src/applications/differential/storage/DifferentialRevision.php

@@ -70,6 +70,7 @@ final class DifferentialRevision extends DifferentialDAO
       ->setAuthorPHID($actor->getPHID())
       ->attachRelationships(array())
       ->attachRepository(null)
+      ->attachActiveDiff(null)
       ->attachReviewerStatus(array())
       ->setStatus(ArcanistDifferentialRevisionStatus::NEEDS_REVIEW);
   }