Move the check for HEAD requests to ::prepare_item_for_response() met…

…hod to preserve BC.

src/wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php

@@ -437,11 +437,6 @@ public function get_item( $request ) {
 			return $comment;
 		}
 
-		if ( $request->is_method( 'HEAD' ) ) {
-			// Don't prepare response body for HEAD requests.
-			return new WP_REST_Response();
-		}
-
 		$data     = $this->prepare_item_for_response( $comment, $request );
 		$response = rest_ensure_response( $data );
 
@@ -1056,6 +1051,12 @@ public function prepare_item_for_response( $item, $request ) {
 		// Restores the more descriptive, specific name for use within this method.
 		$comment = $item;
 
+		// Don't prepare the response body for HEAD requests.
+		if ( $request->is_method( 'HEAD' ) ) {
+			/** This filter is documented in wp-includes/rest-api/endpoints/class-wp-rest-comments-controller.php */
+			return apply_filters( 'rest_prepare_comment', new WP_REST_Response(), $comment, $request );
+		}
+
 		$fields = $this->get_fields_for_response( $request );
 		$data   = array();
 

src/wp-includes/rest-api/endpoints/class-wp-rest-post-types-controller.php

@@ -164,10 +164,6 @@ public function get_item( $request ) {
 			);
 		}
 
-		if ( $request->is_method( 'HEAD' ) ) {
-			return new WP_REST_Response();
-		}
-
 		$data = $this->prepare_item_for_response( $obj, $request );
 
 		return rest_ensure_response( $data );
@@ -187,6 +183,12 @@ public function prepare_item_for_response( $item, $request ) {
 		// Restores the more descriptive, specific name for use within this method.
 		$post_type = $item;
 
+		// Don't prepare the response body for HEAD requests.
+		if ( $request->is_method( 'HEAD' ) ) {
+			/** This filter is documented in wp-includes/rest-api/endpoints/class-wp-rest-post-types-controller.php */
+			return apply_filters( 'rest_prepare_post_type', new WP_REST_Response(), $post_type, $request );
+		}
+
 		$taxonomies = wp_list_filter( get_object_taxonomies( $post_type->name, 'objects' ), array( 'show_in_rest' => true ) );
 		$taxonomies = wp_list_pluck( $taxonomies, 'name' );
 		$base       = ! empty( $post_type->rest_base ) ? $post_type->rest_base : $post_type->name;

src/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php

@@ -643,12 +643,8 @@ public function get_item( $request ) {
 			return $post;
 		}
 
-		if ( $request->is_method( 'HEAD' ) ) {
-			$response = new WP_REST_Response();
-		} else {
-			$data     = $this->prepare_item_for_response( $post, $request );
-			$response = rest_ensure_response( $data );
-		}
+		$data     = $this->prepare_item_for_response( $post, $request );
+		$response = rest_ensure_response( $data );
 
 		if ( is_post_type_viewable( get_post_type_object( $post->post_type ) ) ) {
 			$response->link_header( 'alternate', get_permalink( $post->ID ), array( 'type' => 'text/html' ) );
@@ -1839,6 +1835,12 @@ public function prepare_item_for_response( $item, $request ) {
 
 		setup_postdata( $post );
 
+		// Don't prepare the response body for HEAD requests.
+		if ( $request->is_method( 'HEAD' ) ) {
+			/** This filter is documented in wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php */
+			return apply_filters( "rest_prepare_{$this->post_type}", new WP_REST_Response(), $post, $request );
+		}
+
 		$fields = $this->get_fields_for_response( $request );
 
 		// Base fields for every post.

src/wp-includes/rest-api/endpoints/class-wp-rest-taxonomies-controller.php

@@ -195,10 +195,6 @@ public function get_item( $request ) {
 			);
 		}
 
-		if ( $request->is_method( 'HEAD' ) ) {
-			return new WP_REST_Response();
-		}
-
 		$data = $this->prepare_item_for_response( $tax_obj, $request );
 
 		return rest_ensure_response( $data );
@@ -218,6 +214,12 @@ public function prepare_item_for_response( $item, $request ) {
 		// Restores the more descriptive, specific name for use within this method.
 		$taxonomy = $item;
 
+		// Don't prepare the response body for HEAD requests.
+		if ( $request->is_method( 'HEAD' ) ) {
+			/** This filter is documented in wp-includes/rest-api/endpoints/class-wp-rest-taxonomies-controller.php */
+			return apply_filters( 'rest_prepare_taxonomy', new WP_REST_Response(), $taxonomy, $request );
+		}
+
 		$base = ! empty( $taxonomy->rest_base ) ? $taxonomy->rest_base : $taxonomy->name;
 
 		$fields = $this->get_fields_for_response( $request );

src/wp-includes/rest-api/endpoints/class-wp-rest-terms-controller.php

@@ -477,10 +477,6 @@ public function get_item( $request ) {
 			return $term;
 		}
 
-		if ( $request->is_method( 'HEAD' ) ) {
-			return new WP_REST_Response();
-		}
-
 		$response = $this->prepare_item_for_response( $term, $request );
 
 		return rest_ensure_response( $response );
@@ -900,6 +896,12 @@ public function prepare_item_for_database( $request ) {
 	 */
 	public function prepare_item_for_response( $item, $request ) {
 
+		// Don't prepare the response body for HEAD requests.
+		if ( $request->is_method( 'HEAD' ) ) {
+			/** This filter is documented in wp-includes/rest-api/endpoints/class-wp-rest-terms-controller.php */
+			return apply_filters( "rest_prepare_{$this->taxonomy}", new WP_REST_Response(), $item, $request );
+		}
+
 		$fields = $this->get_fields_for_response( $request );
 		$data   = array();
 

src/wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php

@@ -488,10 +488,6 @@ public function get_item( $request ) {
 			return $user;
 		}
 
-		if ( $request->is_method( 'HEAD' ) ) {
-			return new WP_REST_Response();
-		}
-
 		$user     = $this->prepare_item_for_response( $user, $request );
 		$response = rest_ensure_response( $user );
 
@@ -1011,6 +1007,12 @@ public function prepare_item_for_response( $item, $request ) {
 		// Restores the more descriptive, specific name for use within this method.
 		$user = $item;
 
+		// Don't prepare the response body for HEAD requests.
+		if ( $request->is_method( 'HEAD' ) ) {
+			/** This filter is documented in wp-includes/rest-api/endpoints/class-wp-rest-users-controller.php */
+			return apply_filters( 'rest_prepare_user', new WP_REST_Response(), $user, $request );
+		}
+
 		$fields = $this->get_fields_for_response( $request );
 		$data   = array();
 

tests/phpunit/tests/rest-api/rest-categories-controller.php

@@ -1325,24 +1325,41 @@ public static function data_readable_http_methods() {
 	}
 
 	/**
+	 * @dataProvider data_readable_http_methods
 	 * @ticket 56481
+	 *
+	 * @param string $method The HTTP method to use.
 	 */
-	public function test_get_item_with_head_request_should_not_prepare_category_data() {
+	public function test_get_item_should_allow_adding_headers_via_filter( $method ) {
 		$category_id = self::factory()->category->create();
 
-		$request = new WP_REST_Request( 'HEAD', sprintf( '/wp/v2/categories/%d', $category_id ) );
+		$request = new WP_REST_Request( $method, sprintf( '/wp/v2/categories/%d', $category_id ) );
 
 		$hook_name = 'rest_prepare_category';
 
 		$filter   = new MockAction();
 		$callback = array( $filter, 'filter' );
 		add_filter( $hook_name, $callback );
+		$header_filter = new class() {
+			public static function add_custom_header( $response ) {
+				$response->header( 'X-Test-Header', 'Test' );
+
+				return $response;
+			}
+		};
+		add_filter( $hook_name, array( $header_filter, 'add_custom_header' ) );
 		$response = rest_get_server()->dispatch( $request );
 		remove_filter( $hook_name, $callback );
+		remove_filter( $hook_name, array( $header_filter, 'add_custom_header' ) );
 
 		$this->assertSame( 200, $response->get_status(), 'The response status should be 200.' );
-
-		$this->assertSame( 0, $filter->get_call_count(), 'The "' . $hook_name . '" filter was called when it should not be for HEAD requests.' );
+		$this->assertSame( 1, $filter->get_call_count(), 'The "' . $hook_name . '" filter was called when it should not be for HEAD requests.' );
+		$headers = $response->get_headers();
+		$this->assertArrayHasKey( 'X-Test-Header', $headers, 'The "X-Test-Header" header should be present in the response.' );
+		$this->assertSame( 'Test', $headers['X-Test-Header'], 'The "X-Test-Header" header value should be equal to "Test".' );
+		if ( 'HEAD' !== $method ) {
+			return null;
+		}
 		$this->assertNull( $response->get_data(), 'The server should not generate a body in response to a HEAD request.' );
 	}
 }

tests/phpunit/tests/rest-api/rest-comments-controller.php

@@ -3534,21 +3534,39 @@ public function test_get_items_only_fetches_ids_for_head_requests( $method ) {
 	}
 
 	/**
+	 * @dataProvider data_readable_http_methods
 	 * @ticket 56481
+	 *
+	 * @param string $method The HTTP method to use.
 	 */
-	public function test_get_item_with_head_request_should_not_prepare_comment_data() {
-		$request = new WP_REST_Request( 'HEAD', sprintf( '/wp/v2/comments/%d', self::$approved_id ) );
+	public function test_get_item_with_head_request_should_not_prepare_comment_data( $method ) {
+		$request = new WP_REST_Request( $method, sprintf( '/wp/v2/comments/%d', self::$approved_id ) );
 
 		$hook_name = 'rest_prepare_comment';
 
 		$filter   = new MockAction();
 		$callback = array( $filter, 'filter' );
 		add_filter( $hook_name, $callback );
+		$header_filter = new class() {
+			public static function add_custom_header( $response ) {
+				$response->header( 'X-Test-Header', 'Test' );
+
+				return $response;
+			}
+		};
+		add_filter( $hook_name, array( $header_filter, 'add_custom_header' ) );
 		$response = rest_get_server()->dispatch( $request );
 		remove_filter( $hook_name, $callback );
+		remove_filter( $hook_name, array( $header_filter, 'add_custom_header' ) );
 
 		$this->assertSame( 200, $response->get_status(), 'The response status should be 200.' );
-		$this->assertSame( 0, $filter->get_call_count(), 'The "' . $hook_name . '" filter was called when it should not be for HEAD requests.' );
+		$headers = $response->get_headers();
+		$this->assertSame( 1, $filter->get_call_count(), 'The "' . $hook_name . '" filter was called when it should not be for HEAD requests.' );
+		$this->assertArrayHasKey( 'X-Test-Header', $headers, 'The "X-Test-Header" header should be present in the response.' );
+		$this->assertSame( 'Test', $headers['X-Test-Header'], 'The "X-Test-Header" header value should be equal to "Test".' );
+		if ( 'HEAD' !== $method ) {
+			return null;
+		}
 		$this->assertNull( $response->get_data(), 'The server should not generate a body in response to a HEAD request.' );
 	}
 }

tests/phpunit/tests/rest-api/rest-post-types-controller.php

@@ -79,20 +79,38 @@ public function test_get_item() {
 	}
 
 	/**
+	 * @dataProvider data_readable_http_methods
 	 * @ticket 56481
+	 *
+	 * @param string $method The HTTP method to use.
 	 */
-	public function test_get_item_with_head_request_should_not_prepare_post_type_data() {
-		$request   = new WP_REST_Request( 'HEAD', '/wp/v2/types/post' );
+	public function test_get_item_should_allow_adding_headers_via_filter( $method ) {
+		$request = new WP_REST_Request( $method, '/wp/v2/types/post' );
+
 		$hook_name = 'rest_prepare_post_type';
 		$filter    = new MockAction();
 		$callback  = array( $filter, 'filter' );
 		add_filter( $hook_name, $callback );
+		$header_filter = new class() {
+			public static function add_custom_header( $response ) {
+				$response->header( 'X-Test-Header', 'Test' );
+
+				return $response;
+			}
+		};
+		add_filter( $hook_name, array( $header_filter, 'add_custom_header' ) );
 		$response = rest_get_server()->dispatch( $request );
 		remove_filter( $hook_name, $callback );
+		remove_filter( $hook_name, array( $header_filter, 'add_custom_header' ) );
 
 		$this->assertSame( 200, $response->get_status(), 'The response status should be 200.' );
-
-		$this->assertSame( 0, $filter->get_call_count(), 'The "' . $hook_name . '" filter was called when it should not be for HEAD requests.' );
+		$this->assertSame( 1, $filter->get_call_count(), 'The "' . $hook_name . '" filter was called when it should not be for HEAD requests.' );
+		$headers = $response->get_headers();
+		$this->assertArrayHasKey( 'X-Test-Header', $headers, 'The "X-Test-Header" header should be present in the response.' );
+		$this->assertSame( 'Test', $headers['X-Test-Header'], 'The "X-Test-Header" header value should be equal to "Test".' );
+		if ( 'HEAD' !== $method ) {
+			return null;
+		}
 		$this->assertNull( $response->get_data(), 'The server should not generate a body in response to a HEAD request.' );
 	}
 

tests/phpunit/tests/rest-api/rest-posts-controller.php

@@ -2159,24 +2159,39 @@ public function test_get_item() {
 	}
 
 	/**
+	 * @dataProvider data_readable_http_methods
 	 * @ticket 56481
+	 *
+	 * @param string $method The HTTP method to use.
 	 */
-	public function test_get_item_with_head_request_should_not_prepare_post_data() {
-		$request = new WP_REST_Request( 'HEAD', sprintf( '/wp/v2/posts/%d', self::$post_id ) );
+	public function test_get_item_should_allow_adding_headers_via_filter( $method ) {
+		$request = new WP_REST_Request( $method, sprintf( '/wp/v2/posts/%d', self::$post_id ) );
 
 		$hook_name = 'rest_prepare_' . get_post_type( self::$post_id );
-
-		$filter   = new MockAction();
-		$callback = array( $filter, 'filter' );
+		$filter    = new MockAction();
+		$callback  = array( $filter, 'filter' );
 		add_filter( $hook_name, $callback );
+		$header_filter = new class() {
+			public static function add_custom_header( $response ) {
+				$response->header( 'X-Test-Header', 'Test' );
+
+				return $response;
+			}
+		};
+		add_filter( $hook_name, array( $header_filter, 'add_custom_header' ) );
 		$response = rest_get_server()->dispatch( $request );
 		remove_filter( $hook_name, $callback );
+		remove_filter( $hook_name, array( $header_filter, 'add_custom_header' ) );
 
 		$this->assertSame( 200, $response->get_status(), 'The response status should be 200.' );
-
+		$this->assertSame( 1, $filter->get_call_count(), 'The "' . $hook_name . '" filter was not called when it should be for GET/HEAD requests.' );
 		$headers = $response->get_headers();
-		$this->assertSame( 0, $filter->get_call_count(), 'The "' . $hook_name . '" filter was called when it should not be for HEAD requests.' );
 		$this->assertArrayHasKey( 'Link', $headers, 'The "Link" header should be present in the response.' );
+		$this->assertArrayHasKey( 'X-Test-Header', $headers, 'The "X-Test-Header" header should be present in the response.' );
+		$this->assertSame( 'Test', $headers['X-Test-Header'], 'The "X-Test-Header" header value should be equal to "Test".' );
+		if ( 'HEAD' !== $method ) {
+			return null;
+		}
 		$this->assertNull( $response->get_data(), 'The server should not generate a body in response to a HEAD request.' );
 	}
 

tests/phpunit/tests/rest-api/rest-tags-controller.php

@@ -1579,24 +1579,41 @@ public static function data_readable_http_methods() {
 	}
 
 	/**
+	 * @dataProvider data_readable_http_methods
 	 * @ticket 56481
+	 *
+	 * @param string $method The HTTP method to use.
 	 */
-	public function test_get_item_with_head_request_should_not_prepare_tag_data() {
+	public function test_get_item_should_allow_adding_headers_via_filter( string $method ) {
 		$tag_id = self::factory()->tag->create();
 
-		$request = new WP_REST_Request( 'HEAD', sprintf( '/wp/v2/tags/%d', $tag_id ) );
+		$request = new WP_REST_Request( $method, sprintf( '/wp/v2/tags/%d', $tag_id ) );
 
 		$hook_name = 'rest_prepare_post_tag';
 
 		$filter   = new MockAction();
 		$callback = array( $filter, 'filter' );
 		add_filter( $hook_name, $callback );
+		$header_filter = new class() {
+			public static function add_custom_header( $response ) {
+				$response->header( 'X-Test-Header', 'Test' );
+
+				return $response;
+			}
+		};
+		add_filter( $hook_name, array( $header_filter, 'add_custom_header' ) );
 		$response = rest_get_server()->dispatch( $request );
 		remove_filter( $hook_name, $callback );
+		remove_filter( $hook_name, array( $header_filter, 'add_custom_header' ) );
 
 		$this->assertSame( 200, $response->get_status(), 'The response status should be 200.' );
-
-		$this->assertSame( 0, $filter->get_call_count(), 'The "' . $hook_name . '" filter was called when it should not be for HEAD requests.' );
+		$this->assertSame( 1, $filter->get_call_count(), 'The "' . $hook_name . '" filter was called when it should not be for HEAD requests.' );
+		$headers = $response->get_headers();
+		$this->assertArrayHasKey( 'X-Test-Header', $headers, 'The "X-Test-Header" header should be present in the response.' );
+		$this->assertSame( 'Test', $headers['X-Test-Header'], 'The "X-Test-Header" header value should be equal to "Test".' );
+		if ( 'HEAD' !== $method ) {
+			return null;
+		}
 		$this->assertNull( $response->get_data(), 'The server should not generate a body in response to a HEAD request.' );
 	}
 }