Merge pull request #330 from edx/will/opaque-keys

Handle opaque keys in a backwards-compatible way

apps/openassessment/xblock/openassessmentblock.py

@@ -149,13 +149,14 @@ class OpenAssessmentBlock(
             (dict): The student item associated with this XBlock instance. This
                 includes the student id, item id, and course id.
         """
-        item_id = unicode(self.scope_ids.usage_id)
+
+        item_id = self._serialize_opaque_key(self.scope_ids.usage_id)
 
         # This is not the real way course_ids should work, but this is a
         # temporary expediency for LMS integration
         if hasattr(self, "xmodule_runtime"):
-            course_id = unicode(self.xmodule_runtime.course_id)
-            student_id = self.xmodule_runtime.anonymous_student_id
+            course_id = self._serialize_opaque_key(self.xmodule_runtime.course_id)  # pylint:disable=E1101
+            student_id = self.xmodule_runtime.anonymous_student_id  # pylint:disable=E1101
         else:
             course_id = "edX/Enchantment_101/April_1"
             if self.scope_ids.user_id is None:
@@ -504,3 +505,23 @@ class OpenAssessmentBlock(
         for assessment in self.rubric_assessments:
             if assessment["name"] == mixin_name:
                 return assessment
+
+    def _serialize_opaque_key(self, key):
+        """
+        Gracefully handle opaque keys, both before and after the transition.
+        https://github.com/edx/edx-platform/wiki/Opaque-Keys
+
+        Currently uses `to_deprecated_string()` to ensure that new keys
+        are backwards-compatible with keys we store in ORA2 database models.
+
+        Args:
+            key (unicode or OpaqueKey subclass): The key to serialize.
+
+        Returns:
+            unicode
+
+        """
+        if hasattr(key, 'to_deprecated_string'):
+            return key.to_deprecated_string()
+        else:
+            return unicode(key)

apps/openassessment/xblock/test/test_opaque_keys.py

+# -*- coding: utf-8 -*-
+"""
+Tests for opaque key transition in the LMS runtime.
+See https://github.com/edx/edx-platform/wiki/Opaque-Keys
+"""
+import mock
+from .base import XBlockHandlerTestCase, scenario
+
+
+class TestOpaqueKeys(XBlockHandlerTestCase):
+    """
+    Test that the XBlock handles the opaque key transition gracefully.
+    """
+
+    @scenario('data/basic_scenario.xml', user_id='Bob')
+    def test_opaque_key_deprecated_string(self, xblock):
+        # Simulate the opaque key changeover by
+        # providing a mock `to_deprecated_string()` method.
+        usage_key = mock.MagicMock()
+        usage_key.to_deprecated_string.return_value = u"เՇє๓ เ๔"
+        course_key = mock.MagicMock()
+        course_key.to_deprecated_string.return_value = u"¢συяѕє ι∂"
+
+        xblock.scope_ids = mock.MagicMock()
+        xblock.scope_ids.usage_id = usage_key
+
+        xblock.xmodule_runtime = mock.MagicMock()
+        xblock.xmodule_runtime.course_id = course_key
+
+        student_item = xblock.get_student_item_dict()
+
+        # Expect that we correctly serialize the opaque keys
+        self.assertEqual(student_item['item_id'], u"เՇє๓ เ๔")
+        self.assertEqual(student_item['course_id'], u"¢συяѕє ι∂")