Generate course's LMS URLs for Canvas

lms/models/lms_course.py

@@ -9,13 +9,15 @@
 
 from datetime import datetime
 from typing import TYPE_CHECKING
+from urllib.parse import urljoin
 
 import sqlalchemy as sa
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
 from lms.db import Base
 from lms.models import ApplicationInstance
 from lms.models._mixins import CreatedUpdatedMixin
+from lms.models.family import Family
 
 if TYPE_CHECKING:
     from lms.models import LMSTerm, LMSUser, LTIRole
@@ -63,6 +65,26 @@ class LMSCourse(CreatedUpdatedMixin, Base):
     )
     lms_term: Mapped["LMSTerm"] = relationship()
 
+    application_instances: Mapped[list[ApplicationInstance]] = relationship(
+        secondary="lms_course_application_instance",
+        order_by="desc(LMSCourseApplicationInstance.updated)",
+        viewonly=True,
+    )
+
+    @property
+    def lms_url(self) -> str | None:
+        """The URL of the course in the LMS."""
+        ai = self.application_instances[0]
+        if ai.family != Family.CANVAS:
+            # We only support Canvas for now
+            return None
+
+        if not ai.lms_url or not self.lms_api_course_id:
+            # We need both the LMS base URL and the course ID
+            return None
+
+        return urljoin(ai.lms_url, f"/courses/{self.lms_api_course_id}")
+
 
 class LMSCourseApplicationInstance(CreatedUpdatedMixin, Base):
     """Record of on which installs (application instances) we have seen one course."""

tests/unit/lms/models/lms_course_test.py

@@ -0,0 +1,48 @@
+from datetime import UTC, datetime
+
+import pytest
+
+from lms.models.family import Family
+from tests import factories
+
+
+def test_lms_course_application_instance(db_session):
+    old_ai = factories.ApplicationInstance()
+    new_ai = factories.ApplicationInstance()
+
+    lms_course = factories.LMSCourse()
+    factories.LMSCourseApplicationInstance(
+        lms_course=lms_course,
+        application_instance=old_ai,
+        updated=datetime(2021, 1, 1, tzinfo=UTC),
+    )
+    factories.LMSCourseApplicationInstance(
+        lms_course=lms_course,
+        application_instance=new_ai,
+        updated=datetime(2025, 1, 1, tzinfo=UTC),
+    )
+    db_session.flush()
+
+    assert lms_course.application_instances == [new_ai, old_ai]
+
+
+@pytest.mark.parametrize("family", Family)
+@pytest.mark.parametrize("lms_api_course_id", [None, "COURSE_ID"])
+@pytest.mark.parametrize(
+    "lms_url", ["", "https://example.com", "https://example.com//"]
+)
+def test_lms_url(family, db_session, lms_api_course_id, lms_url):
+    ai = factories.ApplicationInstance(
+        tool_consumer_info_product_family_code=family, lms_url=lms_url
+    )
+    lms_course = factories.LMSCourse(lms_api_course_id=lms_api_course_id)
+
+    factories.LMSCourseApplicationInstance(
+        application_instance=ai, lms_course=lms_course
+    )
+    db_session.flush()
+
+    if family != Family.CANVAS or not lms_api_course_id or not lms_url:
+        assert lms_course.lms_url is None
+    else:
+        assert lms_course.lms_url == "https://example.com/courses/COURSE_ID"