Fix: #6087 Display specific error message for course slug collision (revision)

app/assets/javascripts/utils/api.js

@@ -326,10 +326,14 @@ const API = {
       this.status = response.statusText;
       SentryLogger.obj = this.obj;
       SentryLogger.status = this.status;
-      Sentry.captureMessage('saveCourse failed', {
-        level: 'error',
-        extra: SentryLogger
-      });
+      try {
+        Sentry.captureMessage('saveCourse failed', {
+          level: 'error',
+          extra: SentryLogger
+        });
+      } catch (error) {
+        console.error('Sentry.captureMessage failed:', error);
+      }
       response.responseText = data;
       throw response;
     }

app/controllers/courses_controller.rb

@@ -51,10 +51,15 @@ def update
     ensure_passcode_set
     UpdateCourseWorker.schedule_edits(course: @course, editing_user: current_user)
     render json: { course: @course }
+  rescue Course::DuplicateCourseSlugError => e
+    render_error(:unprocessable_entity, 'courses.error.duplicate_slug', slug: e.slug)
   rescue Wiki::InvalidWikiError => e
-    message = I18n.t('courses.error.invalid_wiki', domain: e.domain)
-    render json: { errors: e, message: },
-           status: :not_found
+    render_error(:not_found, 'courses.error.invalid_wiki', domain: e.domain)
+  end
+
+  def render_error(status, error_key, **params)
+    render json: { errors: params, message: I18n.t(error_key, **params) },
+           status:
   end
 
   def destroy

app/models/course.rb

@@ -593,4 +593,22 @@ def check_course_times
   def set_needs_update
     self.needs_update = true if start_changed?
   end
+
+  # Handle duplicate slug collision
+  validate :check_duplicate_slug, on: :update
+
+  def check_duplicate_slug
+    return unless Course.where(slug: slug).where.not(id: id).exists?
+
+    raise DuplicateCourseSlugError, slug
+  end
+
+  class DuplicateCourseSlugError < StandardError
+    attr_reader :slug
+
+    def initialize(slug, msg = 'Duplicate Slug')
+      @slug = slug
+      super(msg)
+    end
+  end
 end

spec/lib/revision_stat_spec.rb

@@ -49,7 +49,10 @@
 
     context 'course id' do
       context 'not for this course' do
-        before { course.update(id: 1000) }
+        before do
+          allow_any_instance_of(Course).to receive(:check_duplicate_slug).and_return(true)
+          course.update(id: 1000)
+        end
 
         it 'does not include in scope' do
           expect(subject).to eq(0)

spec/models/course_spec.rb

@@ -865,6 +865,26 @@
     end
   end
 
+  describe 'validations' do
+    let!(:existing_course) { create(:course, slug: 'existing-slug') }
+
+    context 'when updating a course' do
+      let!(:duplicate_course) { create(:course, slug: 'duplicate-slug') }
+
+      it 'raises Course::DuplicateCourseSlugError if the slug is duplicated' do
+        # Attempting to update the course with an existing slug should raise an error
+        expect do
+          duplicate_course.update!(slug: existing_course.slug)
+        end.to raise_error(Course::DuplicateCourseSlugError, 'Duplicate Slug')
+      end
+
+      it 'does not raise an error if the slug is unique' do
+        # Updating the course with a unique slug should pass without errors
+        expect { existing_course.update!(slug: 'new-unique-slug') }.not_to raise_error
+      end
+    end
+  end
+
   describe '#approved' do
     let(:course) { create(:course) }