Mock PATCH Partial Update Response

PATCH Partial Update Response

A PATCH endpoint allows clients to update specific fields of a resource without sending the entire object. The response typically returns the complete updated resource so the client can update its local state.

Request vs Response

Request (PATCH /api/users/123):

{
  "name": "Alice Updated",
  "role": "admin"
}

Response (200 OK):

{
  "id": "uuid",
  "name": "Alice Updated",
  "email": "alice@example.com",
  "role": "admin",
  "isActive": true,
  "updatedAt": "2026-02-27T10:30:00Z",
  "createdAt": "2025-01-15T08:00:00Z"
}

Why Return the Full Resource?

Returning the full resource after a PATCH request:

1. Confirms which fields were actually modified
2. Includes server-computed fields like updatedAt
3. Allows the client to update its local cache/state in one step
4. Avoids a subsequent GET request

PATCH vs PUT

Aspect	PATCH	PUT
Sends	Only changed fields	Entire resource
Missing fields	Ignored (unchanged)	Reset to default/null
Idempotent	Not necessarily	Yes
Use case	Update profile name	Replace configuration

Optimistic Updates

With this mock, you can test optimistic update patterns where the UI updates immediately and then reconciles with the server response. If the response differs from the optimistic state, the UI should roll back gracefully.