[wp-trac] [WordPress Trac] #64926: REST API: GET requests fail object/array schema validation when params are JSON-serialized strings

[WordPress Trac]

#64926: REST API: GET requests fail object/array schema validation when params are
JSON-serialized strings
-------------------------+-------------------------------------------------
 Reporter:  dsmy         |       Owner:  (none)
     Type:  defect       |      Status:  new
  (bug)                  |
 Priority:  normal       |   Milestone:  Awaiting Review
Component:  REST API     |     Version:
 Severity:  normal       |  Resolution:
 Keywords:  has-patch    |     Focuses:  javascript, rest-api, php-
                         |  compatibility
-------------------------+-------------------------------------------------

Comment (by westonruter):

 Replying to [comment:15 liaison]:
 > While PHP's bracket notation (?user[name]=Bob) exists, it's not the
 ideal tool for modern decoupled clients or AI-agent integrations (like
 MCP) for several reasons:
 >
 > Lossy Encoding: As noted by @zieladam, bracket notation collapses types
 (e.g., boolean false becomes string "false", null becomes empty string),
 which breaks logic for strict schemas like block attributes.

 I'm not saying that adding JSON parsing fields is a bad idea, but as I
 shared in [comment:13 my comment above], it's not necessarily a lossy
 encoding. The problem with your example endpoint is that it lacks a schema
 for the `object` properties. If I modify your example as follows to add
 `properties`:

 {{{#!php
 <?php
 add_action( 'rest_api_init', function () {
         register_rest_route( 'my-test/v1', '/schema-test', [
                 'methods'  => 'GET',
                 'callback' => fn( WP_REST_Request $req ) => [ 'success' =>
 true, 'data' => $req->get_param( 'config' ) ],
                 'args'     => [
                         'config' => [
                                 'type' => 'object',
                                 'properties' => [
                                         'id' => [
                                                 'type' => 'integer',
                                         ],
                                         'active' => [
                                                 'type' => 'boolean',
                                         ]
                                 ],
                         ]
                 ],
         ] );
 } );
 }}}

 Before adding `properties`, a request to `/wp-json/my-test/v1/schema-
 test?config[id]=123&config[active]=true` would return:


 {{{#!json
 {"success":true,"data":{"id":"123","active":"true"}}
 }}}

 But after adding `properties` then it returns the expected types:

 {{{#!json
 {"success":true,"data":{"id":123,"active":true}}
 }}}

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/64926#comment:18>
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