PATCH success response is undefined (OpenAPI 3.0)

The documentation omits the successful outcome of a partial resource update

Description

A PATCH operation applies a partial modification to a resource. Without a documented success response, callers may not know whether the update completed or how to handle returned data.

Potential impact

Clients or tests may misinterpret the update result and display a state that differs from the server’s state.

Remediation

Define success codes matching the actual update outcome. For example, use 200 when returning a result body or 204 when the update completes without a body. Describe each outcome and any necessary data schema.

Examples

This OpenAPI 3.0 excerpt adds 204 for a completed update that returns no body.

Before

json
{
  "openapi": "3.0.0",
  "paths": {
    "/item": {
      "patch": {
        "operationId": "updateItem",
        "summary": "Updated item",
        "responses": {
          "default": {
            "description": "Error"
          }
        }
      }
    }
  }
}

After

json
{
  "openapi": "3.0.0",
  "paths": {
    "/item": {
      "patch": {
        "operationId": "updateItem",
        "summary": "Update item",
        "responses": {
          "204": {
            "description": "Item updated successfully"
          },
          "default": {
            "description": "Error"
          }
        }
      }
    }
  }
}

References