fix: TypeError: Object of type ZeroCourseGrade is not JSON serializable

ensure Grade is read as JSON

futurex_openedx_extensions/dashboard/serializers.py

@@ -323,12 +323,15 @@ def get_progress(self, obj):  # pylint: disable=no-self-use
         return get_course_blocks_completion_summary(obj.id, user)
 
     def get_grade(self, obj):  # pylint: disable=no-self-use
-        """Return the certificate URL."""
+        """Return the grade summary."""
         collected_block_structure = get_block_structure_manager(obj.id).get_collected()
         course_grade = CourseGradeFactory().read(
             get_user_model().objects.get(id=obj.related_user_id),
             collected_block_structure=collected_block_structure
         )
-        course_grade.update(visible_grades_only=True, has_staff_access=False)
 
-        return course_grade
+        return {
+            'percent': course_grade.percent,
+            'letter_grade': course_grade.letter_grade,
+            'is_passing': course_grade.passed,
+        }

test_utils/edx_platform_mocks/fake_models/models.py

@@ -168,14 +168,15 @@ class CourseGradeFactory:  # pylint: disable=too-few-public-methods
     """Mock"""
     def read(self, *args, **kwargs):  # pylint: disable=no-self-use
         """Mock read"""
-        class Dummy:
-            """dummy class"""
+        class DummyGrade:
+            """dummy grade class"""
+
+            letter_grade = "Fail"
+            percent = 0.4
+            passed = False
+
             def update(self, *args, **kwargs):  # pylint: disable=no-self-use
                 """update"""
                 return None
 
-            def __iter__(self):
-                """__iter__"""
-                return iter([("letter_grade", "Fail"), ("percent", 0.4), ("is_passing", False)])
-
-        return Dummy()
+        return DummyGrade()