delete_metadata_by_mid()

按元ID删除元数据

原型

delete_metadata_by_mid( string $meta_type, int $meta_id )

参数

$meta_type (string) (Required) 对象元数据的类型用于（例如，评论，帖子，术语或用户）。

$meta_id (int) (Required) 特定元行的ID

返回值

(bool)  成功删除时为True，失败时为false。

源文件

路径：wp-includes/meta.php

<?php
...
function delete_metadata_by_mid( $meta_type, $meta_id ) {
	global $wpdb;
	// Make sure everything is valid.
	if ( ! $meta_type || ! is_numeric( $meta_id ) || floor( $meta_id ) != $meta_id ) {
		return false;
	}
	$meta_id = intval( $meta_id );
	if ( $meta_id <= 0 ) {
		return false;
	}
	$table = _get_meta_table( $meta_type );
	if ( ! $table ) {
		return false;
	}
	// object and id columns
	$column = sanitize_key($meta_type . '_id');
	$id_column = 'user' == $meta_type ? 'umeta_id' : 'meta_id';
	/**
	 * Filters whether to delete metadata of a specific type by meta ID.
	 *
	 * The dynamic portion of the hook, `$meta_type`, refers to the meta
	 * object type (comment, post, term, or user). Returning a non-null value
	 * will effectively short-circuit the function.
	 *
	 * @since 5.0.0
	 *
	 * @param null|bool $delete  Whether to allow metadata deletion of the given type.
	 * @param int       $meta_id Meta ID.
	 */
	$check = apply_filters( "delete_{$meta_type}_metadata_by_mid", null, $meta_id );
	if ( null !== $check ) {
		return (bool) $check;
	}
	// Fetch the meta and go on if it's found.
	if ( $meta = get_metadata_by_mid( $meta_type, $meta_id ) ) {
		$object_id = $meta->{$column};
		/** This action is documented in wp-includes/meta.php */
		do_action( "delete_{$meta_type}_meta", (array) $meta_id, $object_id, $meta->meta_key, $meta->meta_value );
		// Old-style action.
		if ( 'post' == $meta_type || 'comment' == $meta_type ) {
			/**
			 * Fires immediately before deleting post or comment metadata of a specific type.
			 *
			 * The dynamic portion of the hook, `$meta_type`, refers to the meta
			 * object type (post or comment).
			 *
			 * @since 3.4.0
			 *
			 * @param int $meta_id ID of the metadata entry to delete.
			 */
			do_action( "delete_{$meta_type}meta", $meta_id );
		}
		// Run the query, will return true if deleted, false otherwise
		$result = (bool) $wpdb->delete( $table, array( $id_column => $meta_id ) );
		// Clear the caches.
		wp_cache_delete($object_id, $meta_type . '_meta');
		/** This action is documented in wp-includes/meta.php */
		do_action( "deleted_{$meta_type}_meta", (array) $meta_id, $object_id, $meta->meta_key, $meta->meta_value );
		// Old-style action.
		if ( 'post' == $meta_type || 'comment' == $meta_type ) {
			/**
			 * Fires immediately after deleting post or comment metadata of a specific type.
			 *
			 * The dynamic portion of the hook, `$meta_type`, refers to the meta
			 * object type (post or comment).
			 *
			 * @since 3.4.0
			 *
			 * @param int $meta_ids Deleted metadata entry ID.
			 */
			do_action( "deleted_{$meta_type}meta", $meta_id );
		}
		return $result;
	}
	// Meta id was not found.
	return false;
}
...
?>

其他

英文文档：https://developer.wordpress.org/reference/functions/delete_metadata_by_mid/