Reduce query counts

submissions/api.py

@@ -14,7 +14,7 @@ from django.db import IntegrityError, DatabaseError
 from dogapi import dog_stats_api
 
 from submissions.serializers import (
-    SubmissionSerializer, StudentItemSerializer, ScoreSerializer
+    SubmissionSerializer, StudentItemSerializer, ScoreSerializer, UnannotatedScoreSerializer
 )
 from submissions.models import Submission, StudentItem, Score, ScoreSummary, ScoreAnnotation, score_set, score_reset
 
@@ -626,8 +626,7 @@ def get_score(student_item):
 
 
 def get_scores(course_id, student_id):
-    """
-    Return a dict mapping item_ids -> [ScoreSerializer(ScoreSummary)].
+    """Return a dict mapping item_ids -> [ScoreSerializer(ScoreSummary)].
 
     This method would be used by an LMS to find all the scores for a given
     student in a given course.
@@ -655,7 +654,7 @@ def get_scores(course_id, student_id):
         score_summaries = ScoreSummary.objects.filter(
             student_item__course_id=course_id,
             student_item__student_id=student_id,
-        ).select_related('latest', 'student_item')
+        ).select_related('latest', 'latest__submission', 'student_item')
     except DatabaseError:
         msg = u"Could not fetch scores for course {}, student {}".format(
             course_id, student_id
@@ -663,7 +662,7 @@ def get_scores(course_id, student_id):
         logger.exception(msg)
         raise SubmissionInternalError(msg)
     scores = {
-        summary.student_item.item_id: ScoreSerializer(summary.latest).data
+        summary.student_item.item_id: UnannotatedScoreSerializer(summary.latest).data
         for summary in score_summaries if not summary.latest.is_hidden()
     }
     return scores

submissions/serializers.py

@@ -96,12 +96,31 @@ class ScoreAnnotationSerializer(serializers.ModelSerializer):
         )
 
 
-class ScoreSerializer(serializers.ModelSerializer):
+class UnannotatedScoreSerializer(serializers.ModelSerializer):
 
     # Ensure that the created_at datetime is not converted to a string.
     created_at = DateTimeField(format=None, required=False)
 
+    class Meta:
+        model = Score
+        fields = (
+            'student_item',
+            'submission',
+            'points_earned',
+            'points_possible',
+            'created_at',
+
+            # Computed
+            'submission_uuid',
+        )
+
+
+class ScoreSerializer(serializers.ModelSerializer):
+
+    # Ensure that the created_at datetime is not converted to a string.
+    created_at = DateTimeField(format=None, required=False)
     annotations = serializers.SerializerMethodField()
+
     def get_annotations(self, obj):
         """
         Inspect ScoreAnnotations to attach all relevant annotations.

submissions/tests/test_api.py

@@ -363,6 +363,7 @@ class TestSubmissionsApi(TestCase):
         student_item['student_id'] = None
         self.assertIs(api.get_score(student_item), None)
 
+    @freeze_time(datetime.datetime.now().replace(tzinfo=pytz.UTC))
     def test_get_scores(self):
         student_item = copy.deepcopy(STUDENT_ITEM)
         student_item["course_id"] = "get_scores_course"
@@ -388,14 +389,35 @@ class TestSubmissionsApi(TestCase):
             scores = api.get_scores(
                 student_item["course_id"], student_item["student_id"]
             )
-            self.assertEqual(
-                scores,
-                {
-                    u"i4x://a/b/c/s1": (2, 5),
-                    u"i4x://a/b/c/s2": (0, 10),
-                    u"i4x://a/b/c/s3": (4, 4),
-                }
-            )
+        self.assertEqual(
+            scores,
+            {
+                u'i4x://a/b/c/s1': {
+                    'created_at': datetime.datetime.now(),
+                    'points_earned': 2,
+                    'points_possible': 5,
+                    'student_item': 1,
+                    'submission': 1,
+                    'submission_uuid': s1['uuid'],
+                },
+                u'i4x://a/b/c/s2': {
+                    'created_at': datetime.datetime.now(),
+                    'points_earned': 0,
+                    'points_possible': 10,
+                    'student_item': 2,
+                    'submission': 2,
+                    'submission_uuid': s2['uuid'],
+                },
+                u'i4x://a/b/c/s3': {
+                    'created_at': datetime.datetime.now(),
+                    'points_earned': 4,
+                    'points_possible': 4,
+                    'student_item': 3,
+                    'submission': 3,
+                    'submission_uuid': s3['uuid'],
+                },
+            }
+        )
 
     def test_get_top_submissions(self):
         student_item_1 = copy.deepcopy(STUDENT_ITEM)

submissions/tests/test_reset_score.py

@@ -137,7 +137,8 @@ class TestResetScore(TestCase):
 
         scores = sub_api.get_scores(self.STUDENT_ITEM['course_id'], self.STUDENT_ITEM['student_id'])
         self.assertIn(self.STUDENT_ITEM['item_id'], scores)
-        self.assertEqual(scores[self.STUDENT_ITEM['item_id']], (3, 4))
+        item_score = scores[self.STUDENT_ITEM['item_id']]
+        self.assertEqual((item_score['points_earned'], item_score['points_possible']), (3, 4))
 
     def test_reset_then_get_score_for_submission(self):
         # Create a submission for the student and score it