{eac}KeyValue Is added to WordPress as a stand-alone, Must Use plugin or by including the file in any project or plugin. It provides a simple API for storing and retrieving key/value pairs with any data type. Integrated tightly with the WordPress object cache (whether the default or a drop-in persistent cache), {eac}KeyValue provides L1 (memory) caching and L2 (MySQL) permanence as well as Write-Back (delayed) or Write-Through (immediate) updating for greater efficiency.

Actors SHOULD use global functions:

set_key_value( $key, $value, [$expires] );          // add/update key/value
set_key_value( $key, null );                        // delete key/value
$value = get_key_value( $key, [$default] );         // read key/value

set_site_key_value( $key, $value, [$expires] );     // add/update site-wide key/value
set_site_key_value( $key, null );                   // delete site-wide key/value
$value = get_site_key_value( $key, [$default] );    // read site-wide key/value

Actors CAN use class methods:

eacKeyValue::put( $key, $value, [$expires] );       // add/update key/value
eacKeyValue::put( $key, null );                     // delete key/value
$value = eacKeyValue::get( $key, [$default] );      // read key/value

$value = eacKeyValue::read( $key, [$toCache] );     // read db value, bypass object cache [and add to cache]
eacKeyValue::write( $key, $value, [$expires] );     // write (immediate) value to db
eacKeyValue::delete( $key );                        // delete (immediate) value from db
eacKeyValue::flush();                               // write cache to db (automatic on shutdown)

Method Arguments:

$key        stringable          The key to store/access
$default    mixed|callable      default value when $key is not found (null)
$value      mixed|null          data to be stored (should not be serialized).
$expires    mixed|null          The expiration of the key/value pair.
                                null            - no expiration
                                int (<= 1 year) - seconds from now
                                int ( > 1 year) - timestamp (UTC)
                                string          - textual datetime, local time (wp_timezone)
                                DateTime object - converted to UTC

Passing $expires with $default to get_key_value() will save the key/value if the default value is used.

Optional Parameters

These parameters alter functionality and are used to determine group keys. As such, they must be used both when setting and when getting a key.

sitewide - For multisite installations, indicates this is a site-wide key/value. Site-wide items apply to all blogs in a multisite environment. sitewide has no effect on a single site installation.

set_key_value( $key, $value, [$expires], "sitewide" );
get_key_value( $key, $default, "sitewide" );

set_site_key_value() and get_site_key_value() automatically add the sitewide option.

set_site_key_value( $key, $value, [$expires] );
get_site_key_value( $key, $default );

transient - Treat this key/value as transient. When using an external object cache, the key/value is not stored in the key-value table, assuming that the object cache will store it.

set_key_value( $key, $value, [$expires], "transient" );
get_key_value( $key, $default, "transient" );

nocache - Marks the key/value as "non-persistent" so an external object cache will not store the key/value. It is stored in the key-value table.

set_key_value( $key, $value, [$expires], "nocache" );
get_key_value( $key, $default, "nocache" );

prefetch - If the object cache supports pre-fetching, indicates this should be a pre-fetched key/value. Pre-fetched items are loaded and cached in a single operation at the start of a request.

set_key_value( $key, $value, [$expires], "prefetch" );
get_key_value( $key, $default, "prefetch" );

encrypt or decrypt - Uses {eac}Doojigger (with encryption extension) to encrypt the value when storing or caching and decrypt the value when retrieving.

set_key_value( $key, $value, [$expires], "encrypt" );
get_key_value( $key, $default, "decrypt" );

Optional parameters (including $expires) may be combined in any order.

// set_key_value: $key, $value must be the first 2 function arguments
set_key_value( $key, $value, $expires, "prefetch", "transient" );
set_key_value( $key, $value, "prefetch", "transient" );
set_key_value( $key, $value, "transient", "prefetch", $expires );

// get_key_value: $key, $default must be the first 2 function arguments
get_key_value( $key, $default, "transient", "sitewide" );
get_key_value( $key, null, "sitewide", "transient" );

Examples:

Store a permanent key/value:

set_key_value( 'my_permanent_key', $value );

Retrieve a key/value:

$value = get_key_value( 'my_permanent_key' );

Store a key/value with an expiration:

set_key_value( 'my_temporary_key', $value, HOUR_IN_SECONDS );
set_key_value( 'my_temporary_key', $value, time() + HOUR_IN_SECONDS );
set_key_value( 'my_temporary_key', $value, '1 hour' );

Set a site-wide, transient key/value:

set_site_key_value('my_transient_key', $value, HOUR_IN_SECONDS, 'transient');
set_key_value('my_transient_key', $value, HOUR_IN_SECONDS, 'transient', 'sitewide');

Retrieve a key with a default value:

$value = get_key_value( 'my_not_found_key', 'default_value' );

Using a callback when retrieving a key:

$value = get_key_value( 'my_not_found_key', function($key, ...$args)
    {
        // do something to generate $value, and save it
        set_key_value( $key, $value, HOUR_IN_SECONDS );
        return $value;
    }
);

$value = get_key_value( 'my_not_found_key', function($key, ...$args)
    {
        // do something to generate $value
        return $value;
    },
    HOUR_IN_SECONDS
);

Store/Retrieve an encrypted key/value:

set_key_value( 'my_encrypted_key', $value, 'encrypt' );
get_key_value( 'my_encrypted_key', null, 'decrypt' );

Delete a key/value:

set_key_value( 'my_permanent_key', null );

Optional constants:

Constants may be defined in wp-config.php.

• When scheduling the automatic purge, set the interval to schedule. Must be a valid WP schedule name.
  define( 'EAC_KEYVALUE_PURGE_SCHEDULE', string|false ); // default: 'daily'

• When scheduling the automatic purge, set the initial start time as timestamp or strtotime.
  define( 'EAC_KEYVALUE_PURGE_START', int|string|false ); // default: 'tomorrow 2:15am'

• Set the maximum number of records to hold before a database commit.
  define( 'EAC_KEYVALUE_AUTO_COMMMIT', int ); // default: 1,000

If the installed object cache has the delayed_writes property set ($wp_object_cache->delayed_writes), this value will override the default auto commit.

• Override (force) the storage of transient keys when using an external object cache.
  define( 'EAC_KEYVALUE_PERSIST_TRANSIENTS', true ); // default: false unless no external object cache

• • -

• Download {eac}KeyValue from the GitHub repository.

• Drop the eacKeyValue.php file into your wp-content/mu-plugins folder and add set_key_value() and get_key_value() calls as needed.

• • -

This plugin is included with and used by {eac}Doojigger, An advanced rapid plugin development platform.

See also: {eac}ObjectCache - a persistent object cache using a SQLite database to cache WordPress objects; A drop-in replacement to the WP_Object_Cache used by WordPress.

Version 1.1.0 – June 27, 2025

• Made this {eac}Doojigger helper a stand-alone MU-Plugin.
• Allow $expires with get_key_value() to set_key_value() the $default value.
• Added encrypt option.
• Added transient option.
• Added nocache option (non-persistent).
• Added sitewide option for multi-site support.
• Added EAC_KEYVALUE_PERSIST_TRANSIENTS constant.
• Support and parse variable argument signatures.
• Cache eacKeyValue dynamic settings (tables & missed keys).
• Global functions get_key_value() / get_site_key_value() / set_key_value() / set_site_key_value()