Question

get_transient( string $transient )

Get the value of a transient.

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description

If the transient does not exist, does not have a value, or has expired, then the return value will be false.

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参数

$transient

(string) (Required) Transient name. Expected to not be SQL-escaped.

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返回值

(mixed) Value of transient.

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源代码

File: wp-includes/option.php

function get_transient( $transient ) {

	/**
	 * Filters the value of an existing transient.
	 *
	 * The dynamic portion of the hook name, `$transient`, refers to the transient name.
	 *
	 * Passing a truthy value to the filter will effectively short-circuit retrieval
	 * of the transient, returning the passed value instead.
	 *
	 * @since 2.8.0
	 * @since 4.4.0 The `$transient` parameter was added
	 *
	 * @param mixed  $pre_transient The default value to return if the transient does not exist.
	 *                              Any value other than false will short-circuit the retrieval
	 *                              of the transient, and return the returned value.
	 * @param string $transient     Transient name.
	 */
	$pre = apply_filters( "pre_transient_{$transient}", false, $transient );
	if ( false !== $pre )
		return $pre;

	if ( wp_using_ext_object_cache() ) {
		$value = wp_cache_get( $transient, 'transient' );
	} else {
		$transient_option = '_transient_' . $transient;
		if ( ! wp_installing() ) {
			// If option is not in alloptions, it is not autoloaded and thus has a timeout
			$alloptions = wp_load_alloptions();
			if ( !isset( $alloptions[$transient_option] ) ) {
				$transient_timeout = '_transient_timeout_' . $transient;
				$timeout = get_option( $transient_timeout );
				if ( false !== $timeout && $timeout < time() ) {
					delete_option( $transient_option  );
					delete_option( $transient_timeout );
					$value = false;
				}
			}
		}

		if ( ! isset( $value ) )
			$value = get_option( $transient_option );
	}

	/**
	 * Filters an existing transient's value.
	 *
	 * The dynamic portion of the hook name, `$transient`, refers to the transient name.
	 *
	 * @since 2.8.0
	 * @since 4.4.0 The `$transient` parameter was added
	 *
	 * @param mixed  $value     Value of transient.
	 * @param string $transient Transient name.
	 */
	return apply_filters( "transient_{$transient}", $value, $transient );
}

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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/load.php: wp_installing()
• wp-includes/cache.php: wp_cache_get()
• wp-includes/load.php: wp_using_ext_object_cache()
• wp-includes/plugin.php: apply_filters()
• wp-includes/option.php: pre_transient_{$transient}
• wp-includes/option.php: transient_{$transient}
• wp-includes/option.php: wp_load_alloptions()
• wp-includes/option.php: delete_option()
• wp-includes/option.php: get_option()
Show 4 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/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-admin/includes/template.php: get_settings_errors()
• wp-includes/cron.php: spawn_cron()
• wp-includes/pluggable.php: wp_rand()
• wp-includes/class-wp-feed-cache-transient.php: WP_Feed_Cache_Transient::load()
• wp-includes/class-wp-feed-cache-transient.php: WP_Feed_Cache_Transient::mtime()
• 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::get()
• wp-includes/rss.php: RSSCache::check_cache()
Show 9 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 Codex

   Example of using get_transient, set_transient and WP_Query

   
   // Get any existing copy of our transient data
   if ( false === ( $special_query_results = get_transient( 'special_query_results' ) ) ) {
   	// It wasn't there, so regenerate the data and save the transient
   	$special_query_results = new WP_Query( 'cat=5&order=random&tag=tech&post_meta_key=thumbnail' );
   	set_transient( 'special_query_results', $special_query_results );
   }
   
   // Use the data like you would have normally...
   

Add WP_DEBUG in the conditional statement if you always want live data during development stage

<?php

if ( WP_DEBUG or false === ( $special_query_results = get_transient( 'special_query_results' ) ) ) ) {
	// It wasn't there, so regenerate the data and save the transient
	$special_query_results = new WP_Query( 'cat=5&order=random&tag=tech&post_meta_key=thumbnail' );
	set_transient( 'special_query_results', $special_query_results );
}

?>