PATCH Method

About¹

The PATCH HTTP method (HTTP verb) applies partial modifications to a resource.

PATCH is similar to the ‘update’ concept found in CRUD (in general, HTTP is different than CRUD, and the two should not be confused). Also known as a PATCH request .

Comparison of PUT and PATCH

1. A PATCH serves as a set of instructions for modifying a resource, whereas PUT method represents a complete replacement of the resource.
2. A PUT request is always idempotent (repeating the same request multiple times results in the resource remaining in the same state), whereas a PATCH request may not always be idempotent. For instance, if a resource includes an auto-incrementing counter, a PUT request will overwrite the counter (since it replaces the entire resource), but a PATCH request may not.

Comparison of PATCH and other methods

Like a POST method , a PATCH can potentially have side effects on other resources.

A server can advertise support for PATCH by adding it to the list in the Allow or Access-Control-Allow-Methods (for Cross-Origin Resource Sharing (CORS) response headers. Another implicit indication that PATCH is supported is the Accept-Patch header (usually after an OPTIONS request on a resource), which lists the media-types the server is able to understand in a PATCH request for a resource.

Characteristics

Syntax

PATCH <request-target>["?"<query>] HTTP/1.1

• <request-target>: identifies the target resource of the request when combined with the information provided in the Host header. This is an absolute path (e.g. /path/to/file.html) in requests to an origin server, and an absolute URL in requests to proxies (e.g. http://www.example.com/path/to/file.html)
• <query> (Optional) - an optional query component preceded by a question-mark ?. Often used to carry identifying information in the form of key=value pairs.

Examples

Successfully modifying a resource

Assume there is a resource on the server representing a user with a numeric ID of 123 in the following format:

{
  "firstName": "Example",
  "LastName": "User",
  "userId": 123,
  "signupDate": "2024-09-09T21:48:58Z",
  "status": "active",
  "registeredDevice": {
    "id": 1,
    "name": "personal",
    "manufacturer": {
      "name": "Hardware corp"
    }
  }
}

Instead of sending a JSON object to fully overwrite a resource, a PATCH modifies only specific parts of the resource. This request updates the status filed:

PATCH /users/123 HTTP/1.1
Host: example.com
Content-Type: application/json
Content-Length: 27
Authorization: Bearer: ABC123

{
  "status": "suspended"
}

The interpretation and authentication of the PATCH request depend on the implementation. Success can be indicated by any of the successful response status codes. In this examnple, a 204 No Content is used as there’s no need to transmit a body with additional context about the operation. An ETag is provided so the caller can perform a conditional request in the future:

HTTP/1.1 204 No Content
Content-Location: /users/122
ETag: "a789sa3s"

Anki

Links

• HTTP method (HTTP verb)
• POST method

References