REST API: Support meta registration for specific object subtypes.

Introduce an `object_subtype` argument to the args array for `register_meta()` which can be used to limit meta registration to a single subtype (e.g. a custom post type or taxonomy, vs all posts or taxonomies).

Introduce `register_post_meta()` and `register_term_meta()` wrapper methods for `register_meta` to provide a convenient interface for the common case of registering meta for a specific taxonomy or post type. These methods work the way plugin developers have often expected `register_meta` to function, and should be used in place of direct `register_meta` where possible.

Props flixos90, tharsheblows, spacedmonkey.
Fixes #38323.



git-svn-id: https://develop.svn.wordpress.org/trunk@43378 602fd350-edb4-49c9-b593-d223f7449a82

1 files changed, 11 insertions, 0 deletions

diff --git a/src/wp-includes/rest-api/fields/class-wp-rest-post-meta-fields.php b/src/wp-includes/rest-api/fields/class-wp-rest-post-meta-fields.php
index e15364246e..d1c3ad6ad9 100644
--- a/src/wp-includes/rest-api/fields/class-wp-rest-post-meta-fields.php
+++ b/src/wp-includes/rest-api/fields/class-wp-rest-post-meta-fields.php
@@ -47,6 +47,17 @@ class WP_REST_Post_Meta_Fields extends WP_REST_Meta_Fields {
 	}
 
 	/**
+	 * Retrieves the object meta subtype.
+	 *
+	 * @since 5.0.0
+	 *
+	 * @return string Subtype for the meta type, or empty string if no specific subtype.
+	 */
+	protected function get_meta_subtype() {
+		return $this->post_type;
+	}
+
+	/**
 	 * Retrieves the type for register_rest_field().
 	 *
 	 * @since 4.7.0