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  1. HTTP (Hypertext Transfer Protocol)
  1. HTTP Headers
  1. Preference-Applied
    1. Usage in responses
      1. Writing responses (servers)
      2. Reading responses (clients)
    2. Overview table
    3. Syntax
      1. Example
    4. Implementations

Preference-Applied

The Preference-Applied response header specifies which preferences were observed, if not otherwise evident by the response.

Usage in responses

Writing responses (servers)

Servers write a Preference-Applied header when they read and act on a preference found in a Prefer header of the request. Servers should write a value for this header for every preference used, since it may be easier for clients to read this header than to inspect the result for the expected outcome.

The server should also emit Vary: Prefer in the event the response is cachable.

See specific HTTP preference descriptions for more information.

Reading responses (clients)

Clients can read the Preference-Applied header to verify the server.

Use of the header is optional, and might be omitted if application of the preference is self-evident.

See specific HTTP preference descriptions for more specific advice.

Overview table

Name
Preference-Applied
Description
Specifies which preferences were observed, if not otherwise evident by the response.
Direction
Response
Specification
RFC 7240: Prefer Header for HTTP

Syntax

Preference-Applied = "Preference-Applied" ":" 1#applied-pref
applied-pref = preference-parameter
preference-parameter = parameter / token

Example

HTTP/1.1 200 OK
Content-Type: application/json
Preference-Applied: return=representation
Content-Location: /my-document

{"a": 1}

Implementations

The Preference-Applied is a syntatic subset of the Prefer header, consider using a library for parsing that header, and looking for tokens with no parameters.