start-date-reset-to-DEFAULT_START_DATE

cms/djangoapps/contentstore/views/item.py

@@ -801,6 +801,8 @@ def create_xblock_info(xblock, data=None, metadata=None, include_ancestor_info=F
     else:
         child_info = None
 
+    release_date = _get_release_date(xblock, user)
+
     if xblock.category != 'course':
         visibility_state = _compute_visibility_state(xblock, child_info, is_xblock_unit and has_changes)
     else:
@@ -835,7 +837,7 @@ def create_xblock_info(xblock, data=None, metadata=None, include_ancestor_info=F
         "published_on": get_default_time_display(xblock.published_on) if published and xblock.published_on else None,
         "studio_url": xblock_studio_url(xblock, parent_xblock),
         "released_to_students": datetime.now(UTC) > xblock.start,
-        "release_date": _get_release_date(xblock, user),
+        "release_date": release_date,
         "visibility_state": visibility_state,
         "has_explicit_staff_lock": xblock.fields['visible_to_staff_only'].is_set_on(xblock),
         "start": xblock.fields['start'].to_json(xblock.start),
@@ -1036,7 +1038,15 @@ def _get_release_date(xblock, user=None):
     Returns the release date for the xblock, or None if the release date has never been set.
     """
     # If year of start date is less than 1900 then reset the start date to DEFAULT_START_DATE
-    if xblock.start.year < 1900 and user:
+    reset_to_default = False
+    try:
+        reset_to_default = xblock.start.year < 1900
+    except ValueError:
+        # For old mongo courses, accessing the start attribute calls `to_json()`,
+        # which raises a `ValueError` for years < 1900.
+        reset_to_default = True
+
+    if reset_to_default and user:
         xblock.start = DEFAULT_START_DATE
         xblock = _update_with_callback(xblock, user)
 

cms/djangoapps/contentstore/views/tests/test_item.py

@@ -1532,7 +1532,6 @@ class TestXBlockInfo(ItemTest):
 
     def test_vertical_xblock_info(self):
         vertical = modulestore().get_item(self.vertical.location)
-        vertical.start = datetime(year=1899, month=1, day=1, tzinfo=UTC)
 
         xblock_info = create_xblock_info(
             vertical,
@@ -1553,6 +1552,29 @@ class TestXBlockInfo(ItemTest):
         )
         self.validate_component_xblock_info(xblock_info)
 
+    @ddt.data(ModuleStoreEnum.Type.split, ModuleStoreEnum.Type.mongo)
+    def test_validate_start_date(self, store_type):
+        """
+        Validate if start-date year is less than 1900 reset the date to DEFAULT_START_DATE.
+        """
+        with self.store.default_store(store_type):
+            course = CourseFactory.create()
+            chapter = ItemFactory.create(
+                parent_location=course.location, category='chapter', display_name='Week 1'
+            )
+
+            chapter.start = datetime(year=1899, month=1, day=1, tzinfo=UTC)
+
+            xblock_info = create_xblock_info(
+                chapter,
+                include_child_info=True,
+                include_children_predicate=ALWAYS,
+                include_ancestor_info=True,
+                user=self.user
+            )
+
+            self.assertEqual(xblock_info['start'], DEFAULT_START_DATE.strftime('%Y-%m-%dT%H:%M:%SZ'))
+
     def validate_course_xblock_info(self, xblock_info, has_child_info=True, course_outline=False):
         """
         Validate that the xblock info is correct for the test course.
@@ -1605,7 +1627,6 @@ class TestXBlockInfo(ItemTest):
         self.assertEqual(xblock_info['display_name'], 'Unit 1')
         self.assertTrue(xblock_info['published'])
         self.assertEqual(xblock_info['edited_by'], 'testuser')
-        self.assertEqual(xblock_info['start'], DEFAULT_START_DATE.strftime('%Y-%m-%dT%H:%M:%SZ'))
 
         # Validate that the correct ancestor info has been included
         ancestor_info = xblock_info.get('ancestor_info', None)