PATCH applies a partial update to an existing resource. Unlike PUT, which conventionally replaces an object, PATCH lets a caller change only selected fields. section 5.5
A practical PATCH handler:
- Accepts the resource identifier, an update command with nullable fields, and a cancellation token. section 5.5
- Loads the existing entity and returns 404 when the identifier is not found. section 5.5
- Assigns each supplied non-null field, saves changes asynchronously, and returns 204 No Content. section 5.5
Updating a book
A BookUpdateCommand containing only Description changes the description while leaving Title unchanged. Returning Ok(book) with 200 is an alternative when the updated object should be returned. section 5.5
