Changeset 41744

Timestamp:

10/04/2017 06:44:41 PM (7 years ago)

Author:

kadamwhite

Message:

REST API: Add _fields parameter to selectively include fields in response JSON.

Allows REST API consumers to specify the specific fields needed in their application code, whitelisting those fields and omitting all others from the returned JSON response object.
This permits applications that only need for example the ID and title of posts to avoid having to transfer the entire rendered post content over the wire alongside the desired fields.
While this whitelisting has no affect on the queries run when preparing the response, it can yield significant reductions in the bandwidth required to transfer a response payload for simple applications.

Props adamsilverstein, TimothyBlynJacobs, svrooij.
Fixes #38131.

Location:

trunk

Files:

• src/wp-includes/rest-api.php (modified) (2 diffs)
• tests/phpunit/tests/rest-api.php (modified) (1 diff)

trunk/src/wp-includes/rest-api.php

@@ -166 +166 @@
     add_filter( 'rest_pre_serve_request', 'rest_send_cors_headers' );
     add_filter( 'rest_post_dispatch', 'rest_send_allow_header', 10, 3 );
+    add_filter( 'rest_post_dispatch', 'rest_filter_response_fields', 10, 3 );
 
     add_filter( 'rest_pre_dispatch', 'rest_handle_options_request', 10, 3 );
@@ -629 +630 @@
         $response->header( 'Allow', implode( ', ', array_map( 'strtoupper', array_keys( $allowed_methods ) ) ) );
     }
+
+    return $response;
+}
+
+/**
+ * Filter the API response to include only a white-listed set of response object fields.
+ *
+ * @since 4.8.0
+ *
+ * @param WP_REST_Response $response Current response being served.
+ * @param WP_REST_Server   $server   ResponseHandler instance (usually WP_REST_Server).
+ * @param WP_REST_Request  $request  The request that was used to make current response.
+ *
+ * @return WP_REST_Response Response to be served, trimmed down to contain a subset of fields.
+ */
+function rest_filter_response_fields( $response, $server, $request ) {
+    if ( ! isset( $request['_fields'] ) || $response->is_error() ) {
+        return $response;
+    }
+
+    $data = $response->get_data();
+
+    $fields = is_array( $request['_fields']  ) ? $request['_fields'] : preg_split( '/[\s,]+/', $request['_fields'] );
+
+    if ( 0 === count( $fields ) ) {
+        return $response;
+    }
+
+    // Trim off outside whitespace from the comma delimited list.
+    $fields = array_map( 'trim', $fields );
+
+    $fields_as_keyed = array_combine( $fields, array_fill( 0, count( $fields ), true ) );
+
+    if ( wp_is_numeric_array( $data ) ) {
+        $new_data = array();
+        foreach ( $data as $item ) {
+            $new_data[] = array_intersect_key( $item, $fields_as_keyed );
+        }
+    } else {
+        $new_data = array_intersect_key( $data, $fields_as_keyed );
+    }
+
+    $response->set_data( $new_data );
 
     return $response;

trunk/tests/phpunit/tests/rest-api.php

@@ -303 +303 @@
 
         $this->assertNull( $response );
+    }
+
+    /**
+     * Ensure that result fields are not whitelisted if no request['_fields'] is present.
+     */
+    public function test_rest_filter_response_fields_no_request_filter() {
+        $response = new WP_REST_Response();
+        $response->set_data( array( 'a' => true ) );
+        $request = array();
+
+        $response = rest_filter_response_fields( $response, null, $request );
+        $this->assertEquals( array( 'a' => true ), $response->get_data() );
+    }
+
+    /**
+     * Ensure that result fields are whitelisted if request['_fields'] is present.
+     */
+    public function test_rest_filter_response_fields_single_field_filter() {
+        $response = new WP_REST_Response();
+        $response->set_data( array(
+            'a' => 0,
+            'b' => 1,
+            'c' => 2,
+        ) );
+        $request = array(
+            '_fields' => 'b'
+        );
+
+        $response = rest_filter_response_fields( $response, null, $request );
+        $this->assertEquals( array( 'b' => 1 ), $response->get_data() );
+    }
+
+    /**
+     * Ensure that multiple comma-separated fields may be whitelisted with request['_fields'].
+     */
+    public function test_rest_filter_response_fields_multi_field_filter() {
+        $response = new WP_REST_Response();
+        $response->set_data( array(
+            'a' => 0,
+            'b' => 1,
+            'c' => 2,
+            'd' => 3,
+            'e' => 4,
+            'f' => 5,
+        ) );
+        $request = array(
+            '_fields' => 'b,c,e'
+        );
+
+        $response = rest_filter_response_fields( $response, null, $request );
+        $this->assertEquals( array(
+            'b' => 1,
+            'c' => 2,
+            'e' => 4,
+        ), $response->get_data() );
+    }
+
+    /**
+     * Ensure that multiple comma-separated fields may be whitelisted
+     * with request['_fields'] using query parameter array syntax.
+     */
+    public function test_rest_filter_response_fields_multi_field_filter_array() {
+        $response = new WP_REST_Response();
+
+        $response->set_data( array(
+            'a' => 0,
+            'b' => 1,
+            'c' => 2,
+            'd' => 3,
+            'e' => 4,
+            'f' => 5,
+        ) );
+        $request = array(
+            '_fields' => array( 'b', 'c', 'e' )
+        );
+
+        $response = rest_filter_response_fields( $response, null, $request );
+        $this->assertEquals( array(
+            'b' => 1,
+            'c' => 2,
+            'e' => 4,
+        ), $response->get_data() );
+    }
+
+    /**
+     * Ensure that request['_fields'] whitelists apply to items in response collections.
+     */
+    public function test_rest_filter_response_fields_numeric_array() {
+        $response = new WP_REST_Response();
+        $response->set_data( array(
+            array(
+                'a' => 0,
+                'b' => 1,
+                'c' => 2,
+            ),
+            array(
+                'a' => 3,
+                'b' => 4,
+                'c' => 5,
+            ),
+            array(
+                'a' => 6,
+                'b' => 7,
+                'c' => 8,
+            ),
+        ) );
+        $request = array(
+            '_fields' => 'b,c'
+        );
+
+        $response = rest_filter_response_fields( $response, null, $request );
+        $this->assertEquals( array(
+            array(
+                'b' => 1,
+                'c' => 2,
+            ),
+            array(
+                'b' => 4,
+                'c' => 5,
+            ),
+            array(
+                'b' => 7,
+                'c' => 8,
+            ),
+        ), $response->get_data() );
     }