From 5f9ba92af4c111e174293eac52684725f422d0cb Mon Sep 17 00:00:00 2001
From: "K. Adam White" <kadamwhite@gmail.com>
Date: Wed, 31 Jul 2019 20:21:56 +0000
Subject: [PATCH] REST API: Skip processing fields which are not present in the
 selected context.

In `WP_REST_Controller::get_fields_for_response()`, exclude fields which are not registered to appear in the request's context.

In conjunction with r45705 this prevents the unnecessary computation of the sample permalink when making a request that is not context=edit.

Props dlh.
Fixes #45605.

Built from https://develop.svn.wordpress.org/trunk@45706


git-svn-id: http://core.svn.wordpress.org/trunk@45517 1a063a9b-81f0-0310-95a4-ce76da25c4cd
---
 .../endpoints/class-wp-rest-controller.php     | 18 +++++++++++++++---
 wp-includes/version.php                        |  2 +-
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-controller.php
index 6188bff380..cd976f3357 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-controller.php
@@ -517,18 +517,30 @@ abstract class WP_REST_Controller {
 	 * @return array Fields to be included in the response.
 	 */
 	public function get_fields_for_response( $request ) {
-		$schema = $this->get_item_schema();
-		$fields = isset( $schema['properties'] ) ? array_keys( $schema['properties'] ) : array();
+		$schema     = $this->get_item_schema();
+		$properties = isset( $schema['properties'] ) ? $schema['properties'] : array();
 
 		$additional_fields = $this->get_additional_fields();
 		foreach ( $additional_fields as $field_name => $field_options ) {
 			// For back-compat, include any field with an empty schema
 			// because it won't be present in $this->get_item_schema().
 			if ( is_null( $field_options['schema'] ) ) {
-				$fields[] = $field_name;
+				$properties[ $field_name ] = $field_options;
 			}
 		}
 
+		// Exclude fields that specify a different context than the request context.
+		$context = $request['context'];
+		if ( $context ) {
+			foreach ( $properties as $name => $options ) {
+				if ( ! empty( $options['context'] ) && ! in_array( $context, $options['context'], true ) ) {
+					unset( $properties[ $name ] );
+				}
+			}
+		}
+
+		$fields = array_keys( $properties );
+
 		if ( ! isset( $request['_fields'] ) ) {
 			return $fields;
 		}
diff --git a/wp-includes/version.php b/wp-includes/version.php
index efaaf3a7fd..618a91244d 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.3-alpha-45705';
+$wp_version = '5.3-alpha-45706';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.