Editor: Add the attachment entity view config for the media editor

src/wp-includes/default-filters.php

@@ -841,7 +841,7 @@
 add_filter( 'rest_pre_insert_wp_template_part', 'inject_ignored_hooked_blocks_metadata_attributes' );
 
 // View Config API.
-foreach ( array( 'page', 'wp_block', 'wp_template_part', 'wp_template' ) as $post_type ) {
+foreach ( array( 'page', 'wp_block', 'wp_template_part', 'wp_template', 'attachment' ) as $post_type ) {
 	// Base definitions run before the default priority, so third-party
 	// callbacks registered at the default compose on top of them
 	// regardless of registration order.

src/wp-includes/view-config.php

@@ -771,6 +771,61 @@ function _wp_get_entity_view_config_posttype_wp_template( $data ) {
 	return $data;
 }
 
+/**
+ * Provides the view configuration for the `attachment` post type.
+ *
+ * An attachment is edited through a form (the media editor) that shares
+ * nothing with the default post type form, so the `form` is replaced: the
+ * editable fields first, in a regular layout, then the metadata and the file
+ * information, in panels. The generic `default_view`, `default_layouts`, and
+ * `view_list` built by wp_get_entity_view_config() are left untouched.
+ *
+ * @since 7.2.0
+ *
+ * @param WP_View_Config_Data $data The view configuration container for the entity.
+ * @return WP_View_Config_Data The updated view configuration container.
+ */
+function _wp_get_entity_view_config_posttype_attachment( $data ) {
+	$regular_layout = array(
+		'type'          => 'regular',
+		'labelPosition' => 'top',
+	);
+
+	return $data->set(
+		array(
+			'form' => array(
+				'layout' => array( 'type' => 'panel' ),
+				'fields' => array(
+					array(
+						'id'     => 'title',
+						'layout' => $regular_layout,
+					),
+					array(
+						'id'     => 'alt_text',
+						'layout' => $regular_layout,
+					),
+					array(
+						'id'     => 'caption',
+						'layout' => $regular_layout,
+					),
+					array(
+						'id'     => 'description',
+						'layout' => $regular_layout,
+					),
+					'date',
+					'author',
+					'filename',
+					'mime_type',
+					'filesize',
+					'media_dimensions',
+					'attached_to',
+				),
+			),
+		),
+		1
+	);
+}
+
 /**
  * Provides the view configuration for the `root`/`site` entity.
  *

tests/phpunit/tests/rest-api/rest-view-config-controller.php

@@ -302,6 +302,34 @@ public function test_get_items_matches_underlying_config() {
 		$this->assertSame( $config['form'], $data['form'] );
 	}
 
+	/**
+	 * The `attachment` post type provides the form of the media editor.
+	 *
+	 * @ticket 66229
+	 *
+	 * @covers ::get_items
+	 */
+	public function test_get_items_attachment_form() {
+		wp_set_current_user( self::$editor_id );
+
+		$response = $this->dispatch_request( 'postType', 'attachment' );
+		$this->assertSame( 200, $response->get_status(), 'The request succeeds.' );
+
+		$data = json_decode( wp_json_encode( $response->get_data() ), true );
+
+		$this->assertSame( array( 'type' => 'panel' ), $data['form']['layout'], 'The form uses a panel layout.' );
+		$this->assertSame(
+			array( 'title', 'alt_text', 'caption', 'description', 'date', 'author', 'filename', 'mime_type', 'filesize', 'media_dimensions', 'attached_to' ),
+			array_map(
+				static function ( $field ) {
+					return is_array( $field ) ? $field['id'] : $field;
+				},
+				$data['form']['fields']
+			),
+			'The form lists the media editor fields in order.'
+		);
+	}
+
 	/**
 	 * The `root`/`site` entity provides the form of the site identity screen.
 	 *

tests/phpunit/tests/view-config.php

@@ -139,6 +139,84 @@ public function data_default_form_post_types() {
 		);
 	}
 
+	/**
+	 * Post types with their own form do not receive the default form groups.
+	 *
+	 * @ticket 66229
+	 *
+	 * @dataProvider data_post_types_with_own_form
+	 *
+	 * @param string $post_type The post type.
+	 */
+	public function test_own_form_post_types_do_not_get_default_groups( $post_type ) {
+		$config = wp_get_entity_view_config( 'postType', $post_type );
+
+		$this->assertNull( $this->get_form_field( $config, 'status' ), 'The `status` group is absent.' );
+		$this->assertNull( $this->get_form_field( $config, 'discussion' ), 'The `discussion` group is absent.' );
+	}
+
+	/**
+	 * Data provider.
+	 *
+	 * @return array[]
+	 */
+	public function data_post_types_with_own_form() {
+		return array(
+			'attachment'       => array( 'attachment' ),
+			'wp_block'         => array( 'wp_block' ),
+			'wp_template'      => array( 'wp_template' ),
+			'wp_template_part' => array( 'wp_template_part' ),
+		);
+	}
+
+	/**
+	 * The `attachment` post type provides the form of the media editor: the
+	 * editable fields in a regular layout, then the rest in panels.
+	 *
+	 * @ticket 66229
+	 *
+	 * @covers ::_wp_get_entity_view_config_posttype_attachment
+	 */
+	public function test_attachment_form() {
+		$config = wp_get_entity_view_config( 'postType', 'attachment' );
+
+		$this->assertSame( array( 'type' => 'panel' ), $config['form']['layout'], 'The form uses a panel layout.' );
+
+		$regular_layout = array(
+			'type'          => 'regular',
+			'labelPosition' => 'top',
+		);
+		$this->assertSame(
+			array(
+				array(
+					'id'     => 'title',
+					'layout' => $regular_layout,
+				),
+				array(
+					'id'     => 'alt_text',
+					'layout' => $regular_layout,
+				),
+				array(
+					'id'     => 'caption',
+					'layout' => $regular_layout,
+				),
+				array(
+					'id'     => 'description',
+					'layout' => $regular_layout,
+				),
+				'date',
+				'author',
+				'filename',
+				'mime_type',
+				'filesize',
+				'media_dimensions',
+				'attached_to',
+			),
+			$config['form']['fields'],
+			'The form lists the media editor fields in order.'
+		);
+	}
+
 	/**
 	 * The default configuration exposes the documented shape for an unknown entity.
 	 */