PATCH in REST and null

Question

We have an article resource with properties:

• title
• image
• description
• status: published | draft

if we want only to remove image we make request

{title: null, image: null, description: null, status: null}

if we want only to update status we make request

{title: null, image: null, description: null, status: draft}

but in this case image also will be removed

How in REST to update only one property?

Answer 1

Performing partial modifications to a resource

The PATCH method can be used to perform partial modifications to a resource. The request payload should contain a set of instructions describing how the resource will be modified. See the following quote from the RFC 5789:

2. The PATCH Method

The PATCH method requests that a set of changes described in the request entity be applied to the resource identified by the Request-URI. [...]

The difference between the PUT and PATCH requests is reflected in the way the server processes the enclosed entity to modify the resource identified by the Request-URI. In a PUT request, the enclosed entity is considered to be a modified version of the resource stored on the origin server, and the client is requesting that the stored version be replaced. With PATCH, however, the enclosed entity contains a set of instructions describing how a resource currently residing on the origin server should be modified to produce a new version. [...]

To describe such set of instructions, you can use JSON Patch defined in the RFC 6902:

1. Introduction

JSON Patch is a format (identified by the media type application/json-patch+json) for expressing a sequence of operations to apply to a target JSON document; it is suitable for use with the HTTP PATCH method.

This format is also potentially useful in other cases in which it is necessary to make partial updates to a JSON document or to a data structure that has similar constraints [...]

Examples with JSON Patch

To update the status, you can do the following:

PATCH /articles/1 HTTP/1.1
Host: example.com
Content-Type: application/json-patch+json

[
  { "op": "replace", "path": "/status", "value": "draft" }
]

Use the following to remove the image:

PATCH /articles/1 HTTP/1.1
Host: example.com
Content-Type: application/json-patch+json

[
  { "op": "remove", "path": "/image" }
]

And use the following to update the status and remove the image:

PATCH /articles/1 HTTP/1.1
Host: example.com
Content-Type: application/json-patch+json

[
  { "op": "replace", "path": "/status", "value": "draft" },
  { "op": "remove", "path": "/image" }
]

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Alternatively to JSON Patch, you may want to consider JSON Merge Patch defined in the RFC 7396: it's also a means of describing a set of modifications to a target resource's content.