HTTP PUT vs PATCH

I so frequently forget the difference between HTTP’s PUT and PATCH methods I figured I’d write it down so that I would have easy access next time I forget.

Overview

PUT and PATCH are similar in that both are HTTP methods used to update RESTful resources. The methods differ in the mechanics of how this updating occurs. In other words, a server will process the request body - the enclosed entity - of a PUT request different than that of a PATCH request.

PUT

When processing a PUT request against a resource, a server will view the body of this request as the new resource, essentially overwriting the existing resource.

Because of this, clients making PUT request against a resource must send the entire resource to ensure it remains intact.

PATCH

On the other hand, a server processing a PATCH request against a resource, views the body of the request as a partial update to the resource. The existing resource is then modified versus being overwritten entirely.

Clients making PATCH requests against a resource must only send the data to update as opposed to the entire resource.