[wp-trac] [WordPress Trac] #47834: Allow un-encoded output / other content types

[WordPress Trac]

#47834: Allow un-encoded output / other content types
-------------------------+-----------------------------
 Reporter:  lkf_tanzt    |      Owner:  (none)
     Type:  enhancement  |     Status:  new
 Priority:  normal       |  Milestone:  Awaiting Review
Component:  REST API     |    Version:  5.2.2
 Severity:  normal       |   Keywords:
  Focuses:               |
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 == The issue

 I want to use the REST-API to provide other content types than JSON. It’s
 possible to set the HTTP header `Content-Type` to other values but the
 data in the the response are always json encoded so they are wrapped in ""
 in the result echoed. The content type is ignored here.

 I followed the program flow to this line:
 https://core.trac.wordpress.org/browser/branches/5.2/src/wp-includes/rest-
 api/class-wp-rest-server.php?rev=45281#L404

 The `$result` is always json encoded, regardless of how the Content-type
 header was set.

 ----

 So what would be a possible solution?


 == 1. Check for content-type header

 One solution would be to query the header flied `Content-Type` from
 `$result` (the headers are already sent in line 361) and encode the
 content only if the header is set to `application/json` or a subtype of
 this.

 So the data are not encoded, if the content-type header is manually set
 for a response to something else, and those other content-types would work
 well. By default the content-type is set to `application/json` and the
 data is encoded, so everything would work as before.

 == 2. Introduce filterable encode switch

 We could introduce a flag {{{$do_json_encode}}} which would allow to skip
 the encoding part by adding a filter on this and returning false.

 A similar thing is done in
 [https://core.trac.wordpress.org/browser/branches/5.2/src/wp-includes
 /rest-api/class-wp-rest-server.php?rev=45281#L380 Line 380] with
 `$served`. So this could look like the following:
 {{{#!php
 $do_json_encode = apply_filters( 'rest_do_json_encode', true, $result,
 $request, $this );
 if ( $do_json_encode ){
     // the currently existing line
     $result = wp_json_encode( $result );
 }
 }}}
 Since the value defaults to `true` the default behaviour would not change
 but we would introduce the option to alter this with a filter and since we
 provide `$result` and `$request` the user/developer can decide on his own
 if he want’s to encode the data or not.

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Ticket URL: <https://core.trac.wordpress.org/ticket/47834>
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