Replace query to fetch an assignments course by the new relationship

lms/models/assignment.py

@@ -1,7 +1,7 @@
 import sqlalchemy as sa
 from sqlalchemy.dialects.postgresql import JSONB
 from sqlalchemy.ext.mutable import MutableDict
-from sqlalchemy.orm import DynamicMapped, Mapped, mapped_column
+from sqlalchemy.orm import DynamicMapped, Mapped, mapped_column, relationship
 
 from lms.db import Base
 from lms.models._mixins import CreatedUpdatedMixin
@@ -81,23 +81,15 @@ class Assignment(CreatedUpdatedMixin, Base):
     groupings: DynamicMapped[Grouping] = sa.orm.relationship(
         secondary="assignment_grouping", viewonly=True, lazy="dynamic"
     )
+    """Any groupings (courses, sections, groups) we have seen this assignment in during a launch"""
 
     membership = sa.orm.relationship(
         "AssignmentMembership", lazy="dynamic", viewonly=True
     )
 
     course_id: Mapped[int | None] = mapped_column(sa.ForeignKey(Course.id))
 
-    @property
-    def course(self):
-        """Course this assignment belongs to."""
-        return (
-            self.groupings.filter_by(type="course")
-            .order_by(Grouping.created.desc())
-            # While logically one assignment belongs to only one course our grouping table might have more
-            # than one row representing the same course. Return the last created one.
-            .first()
-        )
+    course: Mapped[Course | None] = relationship(Course)
 
     def get_canvas_mapped_file_id(self, file_id):
         return self.extra.get("canvas_file_mappings", {}).get(file_id, file_id)

lms/views/admin/assignment.py

@@ -50,6 +50,8 @@ def assignment_dashboard(self):
             )
         )
 
+        # We can only navigate to assignments via their course, assigmentl.course won't be null
+        assert assignment.course
         response = HTTPFound(
             location=self.request.route_url(
                 "dashboard.assignment",

tests/unit/lms/models/assignment_test.py

@@ -1,9 +1,6 @@
-import datetime
-
 import pytest
 
 from lms.models import Assignment
-from tests import factories
 
 
 class TestAssignment:
@@ -33,23 +30,6 @@ def test_get_canvas_mapped_file_id_returns_the_given_file_id_if_no_mapping_exist
     ):
         assert assignment.get_canvas_mapped_file_id("file_id") == "file_id"
 
-    def test_course(self, assignment, db_session):
-        course = factories.Course(created=datetime.datetime(2024, 1, 1))
-        factories.AssignmentGrouping(
-            assignment=assignment, grouping=factories.CanvasSection()
-        )
-        factories.AssignmentGrouping(
-            assignment=assignment, grouping=factories.CanvasGroup()
-        )
-        factories.AssignmentGrouping(
-            assignment=assignment,
-            grouping=factories.Course(created=datetime.datetime(2022, 1, 1)),
-        )
-        factories.AssignmentGrouping(assignment=assignment, grouping=course)
-        db_session.flush()
-
-        assert assignment.course == course
-
     @pytest.fixture
     def assignment(self, db_session):
         assignment = Assignment(

tests/unit/lms/services/dashboard_test.py

@@ -51,15 +51,13 @@ def test_get_request_assignment_for_admin(
         svc,
         organization,
         db_session,
-        application_instance,
+        course,
         get_request_admin_organizations,
     ):
-        assignment = factories.Assignment()
-        course = factories.Course(application_instance=application_instance)
-        factories.AssignmentGrouping(assignment=assignment, grouping=course)
+        assignment = factories.Assignment(course_id=course.id)
+        db_session.flush()
         assignment_service.get_by_id.return_value = assignment
         get_request_admin_organizations.return_value = [organization]
-        db_session.flush()
 
         pyramid_request.matchdict["assignment_id"] = sentinel.id
 
@@ -98,13 +96,11 @@ def test_get_request_course_for_admin(
         pyramid_request,
         course_service,
         svc,
-        application_instance,
         organization,
         get_request_admin_organizations,
+        course,
     ):
-        course_service.get_by_id.return_value = factories.Course(
-            application_instance=application_instance
-        )
+        course_service.get_by_id.return_value = course
         get_request_admin_organizations.return_value = [organization]
         pyramid_request.matchdict["course_id"] = sentinel.id
 
@@ -210,7 +206,13 @@ def organization_service(self, organization_service, organization):
         organization_service.get_hierarchy_ids.return_value = []
         return organization_service
 
-    @pytest.fixture
+    @pytest.fixture()
+    def course(self, db_session, application_instance):
+        course = factories.Course(application_instance=application_instance)
+        db_session.flush()
+        return course
+
+    @pytest.fixture()
     def get_request_admin_organizations(self, svc):
         with patch.object(
             svc, "get_request_admin_organizations"

tests/unit/lms/views/admin/assignment_test.py

@@ -63,8 +63,8 @@ def test_assignment_dashboard(
 
     @pytest.fixture
     def assignment(self, application_instance, db_session):
-        assignment = factories.Assignment()
         course = factories.Course(application_instance=application_instance)
+        assignment = factories.Assignment(course=course)
         factories.AssignmentGrouping(assignment=assignment, grouping=course)
         db_session.flush()  # Give the DB objects IDs
         return assignment

tests/unit/lms/views/dashboard/api/assignment_test.py

@@ -42,7 +42,7 @@ def test_get_assignments(
         }
 
     def test_assignment(
-        self, views, pyramid_request, course, assignment, db_session, dashboard_service
+        self, views, pyramid_request, assignment, db_session, dashboard_service
     ):
         db_session.flush()
         pyramid_request.matchdict["assignment_id"] = sentinel.id
@@ -57,7 +57,7 @@ def test_assignment(
         assert response == {
             "id": assignment.id,
             "title": assignment.title,
-            "course": {"id": course.id, "title": course.lms_name},
+            "course": {"id": assignment.course.id, "title": assignment.course.lms_name},
         }
 
     def test_course_assignments(
@@ -162,7 +162,7 @@ def get_page(self, patch):
 
     @pytest.fixture
     def assignment(self, course):
-        assignment = factories.Assignment()
+        assignment = factories.Assignment(course=course)
         factories.AssignmentGrouping(assignment=assignment, grouping=course)
 
         return assignment