Pull Request resolves #48647 .

• I read the Generative AI policy and my contribution is either not created with the help of AI or is compatible with the policy and GNU/GPL 2 or later.

Summary of Changes

ApiController::delete() fell through to 204 No Content whenever $model->delete() returned false without a model error and without the 409 session flag. The client was told the item was deleted, but it was still there. This happens for example when:

• a content plugin vetoes the delete: plg_content_joomla refuses a trashed category that still has items and only enqueues a message;
• the asset row is missing: Table\Nested::delete() returns false without an error.

Such a refused delete now returns 409 Conflict with "message": "There was an error deleting the item." (existing string JLIB_APPLICATION_ERROR_DELETE). The reason enqueued by the plugin is included in messages.error of the JSON response.

Unchanged: successful deletes (204), not trashed (409), not found (404), model errors (500).

A system test was added to tests/System/integration/api/com_content/Categories.cy.js: deleting a trashed category that still has an article returns 409, and the category is still in the database.

Note: the test proposed in #48643 creates the category with db_createCategory (no asset row). With this fix its delete returns 409 instead of a false 204, so that test needs to create the category via the API.

Testing Instructions

1. In the backend, create a content category, e.g. API delete test, and add one article to it.
2. Trash the category (Content → Categories → Trash).
3. Send a DELETE request with a Super User API token:

   curl -i -X DELETE \
     -H "Authorization: Bearer <api-token>" \
     https://example.test/api/index.php/v1/content/categories/<id>

4. Check Content → Categories with the filter Trashed.
5. Regression: delete the article (and empty the article trash), then repeat step 3. The category must now be deleted with 204.

System test: npx cypress run --spec tests/System/integration/api/com_content/Categories.cy.js

Actual result BEFORE applying this Pull Request

HTTP/1.1 204 No Content

The category is still in the trash.

Expected result AFTER applying this Pull Request

HTTP/1.1 409 Conflict

{"success":true,"message":null,"messages":{"error":["Delete not allowed for category API delete test. One item is assigned to this category."]},"data":{"status":"Conflict","code":409,"message":"There was an error deleting the item."}}

The category is still in the trash. Step 5 returns 204 and the category is deleted.

Link to documentations

Please select:

• Documentation link for guide.joomla.org:

• No documentation changes for guide.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed