Question

set_transient( string $transient,  mixed $value,  int $expiration )

Set/update the value of a transient.

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description

You do not need to serialize values. If the value needs to be serialized, then it will be serialized before it is set.

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参数

$transient

(string) (Required) Transient name. Expected to not be SQL-escaped. Must be 172 characters or fewer in length.

$value

(mixed) (Required) Transient value. Must be serializable if non-scalar. Expected to not be SQL-escaped.

$expiration

(int) (Optional) Time until expiration in seconds. Default 0 (no expiration).

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返回值

(bool) False if value was not set and true if value was set.

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源代码

File: wp-includes/option.php

function set_transient( $transient, $value, $expiration = 0 ) {

	$expiration = (int) $expiration;

	/**
	 * Filters a specific transient before its value is set.
	 *
	 * The dynamic portion of the hook name, `$transient`, refers to the transient name.
	 *
	 * @since 3.0.0
	 * @since 4.2.0 The `$expiration` parameter was added.
	 * @since 4.4.0 The `$transient` parameter was added.
	 *
	 * @param mixed  $value      New value of transient.
	 * @param int    $expiration Time until expiration in seconds.
	 * @param string $transient  Transient name.
	 */
	$value = apply_filters( "pre_set_transient_{$transient}", $value, $expiration, $transient );

	/**
	 * Filters the expiration for a transient before its value is set.
	 *
	 * The dynamic portion of the hook name, `$transient`, refers to the transient name.
	 *
	 * @since 4.4.0
	 *
	 * @param int    $expiration Time until expiration in seconds. Use 0 for no expiration.
	 * @param mixed  $value      New value of transient.
	 * @param string $transient  Transient name.
	 */
	$expiration = apply_filters( "expiration_of_transient_{$transient}", $expiration, $value, $transient );

	if ( wp_using_ext_object_cache() ) {
		$result = wp_cache_set( $transient, $value, 'transient', $expiration );
	} else {
		$transient_timeout = '_transient_timeout_' . $transient;
		$transient_option = '_transient_' . $transient;
		if ( false === get_option( $transient_option ) ) {
			$autoload = 'yes';
			if ( $expiration ) {
				$autoload = 'no';
				add_option( $transient_timeout, time() + $expiration, '', 'no' );
			}
			$result = add_option( $transient_option, $value, '', $autoload );
		} else {
			// If expiration is requested, but the transient has no timeout option,
			// delete, then re-create transient rather than update.
			$update = true;
			if ( $expiration ) {
				if ( false === get_option( $transient_timeout ) ) {
					delete_option( $transient_option );
					add_option( $transient_timeout, time() + $expiration, '', 'no' );
					$result = add_option( $transient_option, $value, '', 'no' );
					$update = false;
				} else {
					update_option( $transient_timeout, time() + $expiration );
				}
			}
			if ( $update ) {
				$result = update_option( $transient_option, $value );
			}
		}
	}

	if ( $result ) {

		/**
		 * Fires after the value for a specific transient has been set.
		 *
		 * The dynamic portion of the hook name, `$transient`, refers to the transient name.
		 *
		 * @since 3.0.0
		 * @since 3.6.0 The `$value` and `$expiration` parameters were added.
		 * @since 4.4.0 The `$transient` parameter was added.
		 *
		 * @param mixed  $value      Transient value.
		 * @param int    $expiration Time until expiration in seconds.
		 * @param string $transient  The name of the transient.
		 */
		do_action( "set_transient_{$transient}", $value, $expiration, $transient );

		/**
		 * Fires after the value for a transient has been set.
		 *
		 * @since 3.0.0
		 * @since 3.6.0 The `$value` and `$expiration` parameters were added.
		 *
		 * @param string $transient  The name of the transient.
		 * @param mixed  $value      Transient value.
		 * @param int    $expiration Time until expiration in seconds.
		 */
		do_action( 'setted_transient', $transient, $value, $expiration );
	}
	return $result;
}

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更新日志

Version	description
2.8.0	Introduced.

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相关函数

Uses

• wp-includes/option.php: expiration_of_transient_{$transient}
• wp-includes/cache.php: wp_cache_set()
• wp-includes/load.php: wp_using_ext_object_cache()
• wp-includes/plugin.php: apply_filters()
• wp-includes/plugin.php: do_action()
• wp-includes/option.php: pre_set_transient_{$transient}
• wp-includes/option.php: set_transient_{$transient}
• wp-includes/option.php: setted_transient
• wp-includes/option.php: add_option()
• wp-includes/option.php: delete_option()
• wp-includes/option.php: update_option()
• wp-includes/option.php: get_option()
Show 7 more uses Hide more uses

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Used By

• wp-includes/class-wp-oembed-controller.php: WP_oEmbed_Controller::get_proxy_item()
• wp-admin/includes/class-wp-plugins-list-table.php: WP_Plugins_List_Table::prepare_items()
• wp-admin/includes/theme-install.php: install_themes_feature_list()
• wp-admin/includes/dashboard.php: wp_dashboard_cached_rss_widget()
• wp-admin/includes/deprecated.php: wp_dashboard_plugins_output()
• wp-includes/cron.php: spawn_cron()
• wp-includes/pluggable.php: wp_rand()
• wp-includes/class-wp-feed-cache-transient.php: WP_Feed_Cache_Transient::save()
• wp-includes/class-wp-feed-cache-transient.php: WP_Feed_Cache_Transient::touch()
• wp-includes/media.php: wp_maybe_generate_attachment_metadata()
• wp-includes/ms-functions.php: get_dirsize()
• wp-includes/author-template.php: is_multi_author()
• wp-includes/rss.php: RSSCache::set()
Show 8 more used by Hide more used by

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User Contributed Notes

1. Skip to note content You must log in to vote on the helpfulness of this noteVote results for this note: 0You must log in to vote on the helpfulness of this note Contributed by Nicola Mustone

   This example shows how to set a transient with the latest five blog posts. It expires after one day.
   It uses time constants to set the expiration time.

   
   // Set the arguments for the custom query
   $args = array(
       'post_type'      => 'post',
       'posts_per_page' => 5,
       'orderby'        => 'date',
       'order'          => 'DESC'
   );
   $latest_post = new WP_Query( $args );
   
   // Save the results in a transient named latest_5_posts
   set_transient( 'latest_5_posts', $latest_post, DAY_IN_SECONDS );
   

   To know more about how to get posts and custom post type items read the documentation of WP_Query.

Saving the $special_query_results object for 12 hours

set_transient( 'special_query_results', $special_query_results, 12 * HOUR_IN_SECONDS );