code-dot-org · artem-vavilov · Feb 10, 2026 · Feb 11, 2026 · Feb 11, 2026 · Feb 11, 2026
diff --git a/dashboard/app/models/lti_course.rb b/dashboard/app/models/lti_course.rb
@@ -15,11 +15,11 @@
 #
 # Indexes
 #
-#  fk_rails_19886eb632                         (lti_deployment_id)
-#  index_lti_courses_on_deleted_at             (deleted_at)
-#  index_lti_courses_on_lti_integration_id     (lti_integration_id)
-#  index_on_context_id_and_lti_integration_id  (context_id,lti_integration_id)
-#  index_on_course_id_and_lti_integration_id   (course_id,lti_integration_id)
+#  fk_rails_19886eb632                              (lti_deployment_id)
+#  index_lti_courses_on_context_integration_active  (`context_id`, `lti_integration_id`, (if((`deleted_at` is null),true,NULL))) UNIQUE
+#  index_lti_courses_on_deleted_at                  (deleted_at)
+#  index_lti_courses_on_lti_integration_id          (lti_integration_id)
+#  index_on_course_id_and_lti_integration_id        (course_id,lti_integration_id)
 #
 class LtiCourse < ApplicationRecord
   acts_as_paranoid

diff --git a/...145032_add_unique_index_to_lti_courses_on_lti_integration_id_and_context_id_and_active.rb b/...145032_add_unique_index_to_lti_courses_on_lti_integration_id_and_context_id_and_active.rb
@@ -0,0 +1,15 @@
+class AddUniqueIndexToLtiCoursesOnLtiIntegrationIdAndContextIdAndActive < ActiveRecord::Migration[6.1]
+  def up
+    execute <<~SQL.squish
+      CREATE UNIQUE INDEX index_lti_courses_on_context_integration_active ON lti_courses (
+        context_id,
+        lti_integration_id,
+        (IF(deleted_at IS NULL, TRUE, NULL)) /* MySQL allows multiple NULL values in a unique index */
+      );
+    SQL
+  end
+
+  def down
+    remove_index :lti_courses, name: :index_lti_courses_on_context_integration_active, if_exists: true
+  end
+end
diff --git a/...rate/20260211145245_remove_index_from_lti_courses_on_context_id_and_lti_integration_id.rb b/...rate/20260211145245_remove_index_from_lti_courses_on_context_id_and_lti_integration_id.rb
@@ -0,0 +1,5 @@
+class RemoveIndexFromLtiCoursesOnContextIdAndLtiIntegrationId < ActiveRecord::Migration[6.1]
+  def change
+    remove_index :lti_courses, %i[context_id lti_integration_id], name: :index_on_context_id_and_lti_integration_id
+  end
+end
diff --git a/dashboard/db/schema.rb b/dashboard/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2026_01_28_232147) do
+ActiveRecord::Schema.define(version: 2026_02_11_145245) do
 
   create_table "activities", id: :integer, charset: "utf8mb3", collation: "utf8mb3_unicode_ci", force: :cascade do |t|
     t.integer "user_id"
@@ -1066,7 +1066,7 @@
     t.datetime "created_at", precision: 6, null: false
     t.datetime "updated_at", precision: 6, null: false
     t.datetime "deleted_at"
-    t.index ["context_id", "lti_integration_id"], name: "index_on_context_id_and_lti_integration_id"
+    t.index "`context_id`, `lti_integration_id`, (if((`deleted_at` is null),true,NULL))", name: "index_lti_courses_on_context_integration_active", unique: true
     t.index ["course_id", "lti_integration_id"], name: "index_on_course_id_and_lti_integration_id"
     t.index ["deleted_at"], name: "index_lti_courses_on_deleted_at"
     t.index ["lti_deployment_id"], name: "fk_rails_19886eb632"

diff --git a/dashboard/test/factories/factories.rb b/dashboard/test/factories/factories.rb
@@ -2125,8 +2125,8 @@
   end
 
   factory :lti_course do
-    lti_integration {create(:lti_integration)}
-    lti_deployment {create(:lti_deployment, lti_integration: lti_integration)}
+    association :lti_integration
+    lti_deployment {build(:lti_deployment, lti_integration:)}
     context_id {SecureRandom.uuid}
     course_id {SecureRandom.uuid}
     nrps_url {"http://test.org/api/names_and_roles"}

diff --git a/dashboard/test/models/lti_course_test.rb b/dashboard/test/models/lti_course_test.rb
@@ -36,4 +36,38 @@ class LtiCourseTest < ActiveSupport::TestCase
       assert lti_section.reload.deleted_at.present?, "lti_section should be deleted"
     end
   end
+
+  describe 'unique constraint on (context_id, lti_integration_id, active)' do
+    subject(:lti_course_duplicate) do
+      build(:lti_course).tap do |duplicate|
+        duplicate.lti_integration = lti_course_original.lti_integration
+        duplicate.context_id      = lti_course_original.context_id
+        duplicate.deleted_at      = nil
+        duplicate.save!(validate: false)
+      end
+    end
+
+    let!(:lti_course_original) {create(:lti_course)}
+
+    it 'raises ActiveRecord::RecordNotUnique' do
+      exception = _ {lti_course_duplicate}.must_raise ActiveRecord::RecordNotUnique
+      _(exception.message).must_match /Duplicate entry .* for key 'lti_courses.index_lti_courses_on_context_integration_active'/
+    end
+
+    context 'when original record is soft deleted' do
+      before do
+        lti_course_original.destroy!
+      end
+
+      it 'allows to create duplicate' do
+        _ {lti_course_duplicate}.must_differ 'LtiCourse.count'
+        _(lti_course_duplicate.persisted?).must_equal true
+      end
+
+      it 'allows to delete duplicate' do
+        _ {lti_course_duplicate.destroy!}.must_differ 'LtiCourse.only_deleted.count'
+        _(lti_course_duplicate.deleted?).must_equal true
+      end
+    end
+  end
 end