fix: CourseRun database constraint wasn't working with CCX keys

Author: bradenmacdonald

src/openedx_catalog/migrations/0001_initial.py

@@ -1,7 +1,6 @@
 # Generated by Django 5.2.11 on 2026-02-10 03:08
 
 import django.db.models.deletion
-import django.db.models.expressions
 import django.db.models.functions.text
 import django.db.models.lookups
 import opaque_keys.edx.django.models
@@ -174,7 +173,10 @@ class Migration(migrations.Migration):
         migrations.AddConstraint(
             model_name="courserun",
             constraint=models.UniqueConstraint(
-                models.F("catalog_course"), models.F("run"), name="oex_catalog_courserun_catalog_course_run_uniq"
+                models.F("catalog_course"),
+                models.F("run"),
+                condition=models.Q(("course_id__startswith", "ccx"), _negated=True),
+                name="oex_catalog_courserun_catalog_course_run_uniq",
             ),
         ),
         migrations.AddConstraint(
@@ -198,14 +200,8 @@ class Migration(migrations.Migration):
         migrations.AddConstraint(
             model_name="courserun",
             constraint=models.CheckConstraint(
-                condition=django.db.models.lookups.Exact(
-                    django.db.models.functions.text.Right(
-                        "course_id",
-                        django.db.models.expressions.CombinedExpression(
-                            django.db.models.functions.text.Length("run"), "+", models.Value(1)
-                        ),
-                    ),
-                    django.db.models.functions.text.Concat(models.Value("+"), "run"),
+                condition=django.db.models.lookups.GreaterThan(
+                    django.db.models.functions.text.StrIndex("course_id", models.F("run")), 0
                 ),
                 name="oex_catalog_courserun_courseid_run_match_exactly",
                 violation_error_message="The CourseRun 'run' field should match the run in the course_id key.",

src/openedx_catalog/models/course_run.py

@@ -7,8 +7,9 @@
 from django.contrib import admin
 from django.core.exceptions import ValidationError
 from django.db import models
-from django.db.models.functions import Concat, Length, Lower, Right
-from django.db.models.lookups import Exact
+from django.db.models import F
+from django.db.models.functions import Length, Lower, StrIndex
+from django.db.models.lookups import GreaterThan
 from django.utils.translation import gettext_lazy as _
 from opaque_keys import InvalidKeyError
 from opaque_keys.edx.django.models import CourseKeyField
@@ -214,19 +215,26 @@ class Meta:
         ordering = ("-created",)
         constraints = [
             # catalog_course (org+course_code) and run must be unique together:
-            models.UniqueConstraint("catalog_course", "run", name="oex_catalog_courserun_catalog_course_run_uniq"),
+            models.UniqueConstraint(
+                "catalog_course",
+                "run",
+                name="oex_catalog_courserun_catalog_course_run_uniq",
+                # With one unfortunate exception: CCX courses all have the same org, code, and run exactly:
+                condition=~models.Q(course_id__startswith="ccx"),
+            ),
             # course_id is case-sensitively unique but we also want it to be case-insensitively unique:
             models.UniqueConstraint(Lower("course_id"), name="oex_catalog_courserun_course_id_ci"),
             # Enforce at the DB level that these required fields are not blank:
             models.CheckConstraint(condition=models.Q(run__length__gt=0), name="oex_catalog_courserun_run_not_blank"),
             models.CheckConstraint(
                 condition=models.Q(display_name__length__gt=0), name="oex_catalog_courserun_display_name_not_blank"
             ),
-            # Enforce that the course ID must end with "+run" where "run" is an exact match for the "run" field.
-            # This check may be removed or changed in the future if our course ID format ever changes
+            # Enforce at the DB level that the "run" field value appears in the course ID:
             models.CheckConstraint(
-                # Note: EndsWith() on SQLite is always case-insensitive, so we code the constraint like this:
-                condition=Exact(Right("course_id", Length("run") + 1), Concat(models.Value("+"), "run")),
+                condition=GreaterThan(StrIndex("course_id", F("run")), 0),
+                # The following check condition (ends with "+run") is even stronger, but doesn't work with CCX keys
+                # like "ccx-v1:org+code+run+ccx@1" which we also need to support.
+                #     condition=Exact(Right("course_id", Length("run") + 1), Concat(models.Value("+"), "run")),
                 name="oex_catalog_courserun_courseid_run_match_exactly",
                 violation_error_message=_("The CourseRun 'run' field should match the run in the course_id key."),
             ),

tests/openedx_catalog/test_models.py

@@ -321,3 +321,8 @@ def test_run_exact(org1) -> None:
             CourseRun.objects.filter(pk=run.pk).update(
                 course_id=CourseLocator(org="Org1", course="Test302", run="mixedcase"),
             )
+
+
+# TODO: it would be good to test here that CourseRun objects work correctly with CCX keys like
+# "ccx-v1:org+code+run+ccx@1", but I don't want to introduce a dependency on edx-ccx-keys for now. Once we consolidate
+# all the key types into a single repo, we can add a test here.