Add consecutive_order, parent_name and status to exercise API

Add a consecutive numbering to the API to indicate the order of learning
objects (chapters and exercises). This is calculated dynamically.

Add a field to the API "parent_name", which contains the name of the
parent, i.e., the chapter or exercise the exercise is embedded in (if it
is embedded).
The name of the chapter can provide more understandable context than
just the exercise path or the title of the exercise (e.g. "Feedback").

The consecutive_order field is used to fix Jutut issues #43 and #44.
The parent_name field is used to fix Jutut issue #46.
The status can be used to identify enrollment questionnaires, needed
for fixing Jutut issue #31.

exercise/api/full_serializers.py

@@ -10,7 +10,10 @@
 from course.api.serializers import CourseBriefSerializer
 from userprofile.api.serializers import UserBriefSerializer
 
-from ..models import Submission
+from ..models import (
+    Submission,
+    BaseExercise
+)
 from .serializers import (
     ExerciseBriefSerializer,
     SubmissionBriefSerializer,
@@ -31,6 +34,8 @@
 class ExerciseSerializer(ExerciseBriefSerializer):
     course = CourseBriefSerializer(source='course_instance')
     post_url = serializers.SerializerMethodField()
+    consecutive_order = serializers.SerializerMethodField()
+    parent_name = serializers.SerializerMethodField()
     exercise_info = serializers.JSONField()
     submissions = NestedHyperlinkedIdentityField(
         view_name='api:exercise-submissions-list',
@@ -60,18 +65,32 @@ def get_post_url(self, obj):
             return request.build_absolute_uri(url)
         return None
 
+    def get_consecutive_order(self, obj: BaseExercise) -> int:
+        content = self.context['cached_content']
+        order = content.get_absolute_order_number(obj.id)
+        return order
+
+    def get_parent_name(self, obj: BaseExercise) -> str:
+        parent = obj.parent
+        if parent is None:
+            return None
+        return str(parent)
+
     class Meta(ExerciseBriefSerializer.Meta):
         fields = (
             'name',
             'course',
             'is_submittable',
             'post_url',
+            'consecutive_order',
+            'parent_name',
             'exercise_info',
             'templates',
             'submissions',
             'my_submissions',
             'my_stats',
             'statistics',
+            'status',
         )
 
 

exercise/api/views.py

@@ -81,6 +81,11 @@ class ExerciseViewSet(mixins.RetrieveModelMixin,
     serializer_class = ExerciseSerializer
     queryset = BaseExercise.objects.all()
 
+    def get_serializer_context(self):
+        context = super().get_serializer_context()
+        context.update({'cached_content': self.content})
+        return context
+
     @action(
         detail=True,
         url_path='grader',

exercise/cache/hierarchy.py

@@ -1,3 +1,4 @@
+from typing import Tuple
 from django.http.response import Http404
 from course.models import CourseModule, LearningObjectCategory
 from ..models import LearningObject
@@ -172,6 +173,27 @@ def find(self, model):
             self._next(idx, tree),
         )
 
+    def get_absolute_order_number(self, learning_object_id: int) -> int:
+        """Get the absolute order number of the given learning object
+        (i.e. how manieth chapter or exercise it is in the material).
+        """
+        def inner(parent: dict, n: int) -> Tuple[bool, int]:
+            # parent is a cached dict representing a CourseModule or a LearningObject
+            for entry in parent['children']:
+                n += 1
+                if entry['id'] == learning_object_id:
+                    return True, n
+                found, n = inner(entry, n)
+                if found:
+                    return True, n
+            return False, n
+
+        n = 0
+        for module in self.modules():
+            found, n = inner(module, n)
+            if found:
+                return n
+
     def search_exercises(self, **kwargs):
         _, entries = self.search_entries(**kwargs)
         return [e for e in entries if e['type'] == 'exercise']