Add `wp post meta clean-duplicates <id> <key>` command

[danielbachhuber]

Feature Request

• Yes, I reviewed the contribution guidelines.

Describe your use case and the problem you are facing

It would be helpful to have a wp post meta clean-duplicates <id> <key> command to clean up duplicated post meta (key and value are the exact same).

For example, on a user's blog we somehow ended up with multiple enclosure post meta with the same value. This caused the same enclosure to be added multiple times to the RSS <item>, invalidating the feed.

Describe the solution you'd like

A command to easily clean up post meta with the same key and value.

It might even be as easy as this code!

<?php
/**
 * Cleans duplicate closures on a post.
 */

class Clean_Duplicate_Enclosures {

	/**
	 * Cleans up duplicate 'enclosure' post meta values on a post.
	 * 
	 * ## OPTIONS
	 * 
	 * <id>
	 * : ID of the post to clean.
	 * 
	 * <key>
	 * : Meta key to clean up.
	 *
	 * ## EXAMPLES
	 * 
	 *     wp post meta clean-duplicate-enclosures 1234 enclosure
	 */
	public function __invoke( $args ) {
		global $wpdb;

		list( $post_id, $key ) = $args;

		$metas = $wpdb->get_results(
			$wpdb->prepare(
				"SELECT * FROM {$wpdb->postmeta} WHERE meta_key=%s AND post_id=%d",
				$key,
				$post_id
			)
		);

		$uniq_enclosures = [];
		$dupe_enclosures = [];
		foreach ( $metas as $meta ) {
			if ( ! isset( $uniq_enclosures[ $meta->meta_value ] ) ) {
				$uniq_enclosures[ $meta->meta_value ] = (int) $meta->meta_id;
			} else {
				$dupe_enclosures[] = (int) $meta->meta_id;
			}
		}

		if ( count( $dupe_enclosures ) ) {
			WP_CLI::confirm(
				sprintf(
					'Are you sure you want to delete %d duplicate enclosures and keep %d valid enclosures?',
					count( $dupe_enclosures ),
					count( $uniq_enclosures )
				)
			);
			foreach( $dupe_enclosures as $meta_id ) {
				delete_metadata_by_mid( 'post', $meta_id );
				WP_CLI::log( sprintf( 'Deleted meta id %d.', $meta_id ) );
			}
			WP_CLI::success( 'Cleaned up duplicate enclosures.' );
		} else {
			WP_CLI::success(
				sprintf(
					'Nothing to clean up: found %d valid enclosures and %d duplicate enclosures.',
					count( $uniq_enclosures ),
					count( $dupe_enclosures )
				)
			);
		}
	}

}

WP_CLI::add_command( 'post meta clean-duplicate-enclosures', 'Clean_Duplicate_Enclosures' );

[danielbachhuber]

The underlying cause for this problem: WordPress/wordpress-importer#76