Created a generic list formatting helper class for this, to align with
logic used on the search results endpoint and for easier future re-use
in a standardised way.
Also updated some class property types.
Added test to cover new books-contents results.
Related to #3734
- Updates book/shelf cover image handling for easier cloning/handling.
- Adds core logic for promoting books/chapters up a level.
- Enables usage of book/shelf cover image via API.
Related to #1087
- Fixed page editor default focus not working as expected due to
misnamed attribute.
- Added owned_by to relevant areas of the API including the docs.
- Made book relation on page accessible even if deleted since it could cause an issue on views, such as audit trail, when the relation is accessed when the book is deleted.
Repos are generally better since otherwise we end up duplicating
things between front-end and API.
Types moved to by CONST values within a class for better visibilty
of usage and listing of types.
