kellenmace/delete-transients-by-prefix.php

## delete-transients-by-prefix.php
<?php

/**
 * Searches the database for transients stored there that match a specific prefix.
 *
 * @author Brad Parbs, Kellen Mace
 * @param  string $prefix prefix to search for.
 * @return array          nested array response for wpdb->get_results.
 */
function wds_campbell_search_database_for_transients_by_prefix( $prefix ) {

	global $wpdb;

	// Add our prefix after concating our prefix with the _transient prefix
	$prefix = $wpdb->esc_like( '_transient_' . $prefix . '_' );

	// Build up our SQL query
	$sql = "SELECT `option_name` FROM $wpdb->options WHERE `option_name` LIKE '%s'";

	// Execute our query
	$transients = $wpdb->get_results( $wpdb->prepare( $sql, $prefix . '%' ), ARRAY_A );

	// If if looks good, pass it back
	if ( $transients && ! is_wp_error( $transients ) ) {
		return $transients;
	}

	// Otherise return false
	return false;
}

/**
 * Expects a passed in multidimensional array of transient keys
 *  array(
 *    array( 'option_name' => '_transient_blah_blah' ),
 *    array( 'option_name' => 'transient_another_one' ),
 * Can also pass in an array of transient names
 *
 * @author Brad Parbs, Kellen Mace
 * @param  array|string $transients  Nested array of transienets, keyed by option_name,
 *                                   or array of names of transients.j
 * @return array                     Count of total vs deleted.
 */
function wds_campbell_delete_transients_from_keys( $transients ) {

	if ( ! isset( $transients ) ) {
		return false;
	}

	// If we get a string key passed in, might as well use it correctly
	if ( is_string( $transients ) ) {
		$transients = array( array( 'option_name' => $transients ) );
	}

	// If its not an array, we can't do anything
	if ( ! is_array( $transients ) ) {
		return false;
	}

	$results = array();

	// Loop through our transients
	foreach ( $transients as $transient ) {

		if ( is_array( $transient ) ) {

			// If we have an array, grab the first element
			$transient = current( $transient );
		}

		// Remove that sucker
		$results[ $transient ] = delete_transient( str_replace( '_transient_', '', $transient ) );
	}

	// Return an array of total number, and number deleted
	return array(
		'total'   => count( $results ),
		'deleted' => array_sum( $results ),
	);

}

/**
 * Delete brands select menu transients
 *
 * @author Kellen Mace
 */
function wds_delete_brands_region_transients() {
	wds_campbell_delete_transients_from_keys( wds_campbell_search_database_for_transients_by_prefix( 'wds_campbell_brand_regions' ) );
}
add_action( 'create_region', 'wds_delete_brands_region_transients' );
add_action( 'edit_region', 'wds_delete_brands_region_transients' );
add_action( 'delete_region', 'wds_delete_brands_region_transients' );