Use PATCH instead of PUT for partial updates
As only the properties present in the body of the request are updated, leaving properties which aren't present intact, a PATCH (or even POST) method would be more appropriate than PUT (which implies a full replacement of the entity).
In addition, client apps should try to send as few updated properties as possible, to avoid overwriting data that may have been changed elsewhere.
For example, send updateFragment({ id: fragment.id, title: fragment.title })
instead of updateFragment(fragment)
when only the title is edited.