Better specify nested prefetch lookups

Author: fjsj

CHANGELOG.md

@@ -4,6 +4,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.2.0]
+
+- Add support to nested prefetch lookups like `v.VirtualModel(manager=User.objects, lookup="course__facilitators")`
+  * Warning: this will remain undocumented for now, because the behavior is strange:
+             the prefetch is made inside `course` in this case, due to Django behavior.
+- Add parameter `serializer_context` to be used in `v.Annotation` and `get_prefetch_queryset`.
+
 ## [0.1.6]
 
 - Fix support for custom manager in `VirtualModel` initialization

tests/optimization/test_lookup_finder.py

@@ -180,8 +180,8 @@ class Meta:
 
     @hints.defined_on_virtual_model()
     def get_facilitator_users(self, lesson):
-        if hasattr(lesson, "facilitator_users"):
-            return list({u.email for u in lesson.facilitator_users})
+        if hasattr(lesson.course, "facilitator_users"):
+            return list({u.email for u in lesson.course.facilitator_users})
 
         # this won't run because it's defined on virtual model,
         # but one could add fallback code here:

tests/virtual_models/test_virtual_models.py

@@ -432,3 +432,23 @@ class Meta:
 
             for completed_lesson in completed_lesson_list:
                 assert isinstance(completed_lesson.lesson.course.created_by, User)
+
+    def test_prefetch_with_nested_lookup(self):
+        class VirtualLesson(v.VirtualModel):
+            facilitator_users = v.VirtualModel(manager=User.objects, lookup="course__facilitators")
+
+            class Meta:
+                model = Lesson
+
+        virtual_model = VirtualLesson()
+        qs = Lesson.objects.all()
+        lookup_list = ["facilitator_users"]
+
+        optimized_qs = virtual_model.get_optimized_queryset(qs=qs, lookup_list=lookup_list)
+        with self.assertNumQueries(3):
+            lesson_list = list(optimized_qs)
+            assert len(lesson_list) == 9
+
+            for lesson in lesson_list:
+                for user in lesson.course.facilitator_users:
+                    assert isinstance(user, User)