Title: WP_Customize_Setting
Published: April 25, 2014
Last modified: May 20, 2026

---

# class WP_Customize_Setting {}

## In this article

 * [Description](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#description)
    - [See also](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#see-also)
 * [Methods](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#methods)
 * [Source](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#source)
 * [Related](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#related)
 * [Changelog](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#changelog)

[ Back to top](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#wp--skip-link--target)

Customize Setting class.

## 󠀁[Description](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#description)󠁿

Handles saving and sanitizing of settings.

### 󠀁[See also](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#see-also)󠁿

 * [WP_Customize_Manager](https://developer.wordpress.org/reference/classes/wp_customize_manager/)

## 󠀁[Methods](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#methods)󠁿

| Name | Description | 
| [WP_Customize_Setting::__construct](https://developer.wordpress.org/reference/classes/wp_customize_setting/__construct/) | Constructor. | 
| [WP_Customize_Setting::_clear_aggregated_multidimensional_preview_applied_flag](https://developer.wordpress.org/reference/classes/wp_customize_setting/_clear_aggregated_multidimensional_preview_applied_flag/) | Clear out the previewed-applied flag for a multidimensional-aggregated value whenever its post value is updated. | 
| [WP_Customize_Setting::_multidimensional_preview_filter](https://developer.wordpress.org/reference/classes/wp_customize_setting/_multidimensional_preview_filter/) | Callback function to filter multidimensional theme mods and options. | 
| [WP_Customize_Setting::_preview_filter](https://developer.wordpress.org/reference/classes/wp_customize_setting/_preview_filter/) | Callback function to filter non-multidimensional theme mods and options. | 
| [WP_Customize_Setting::_update_option](https://developer.wordpress.org/reference/classes/wp_customize_setting/_update_option/) | Deprecated method. — deprecated | 
| [WP_Customize_Setting::_update_theme_mod](https://developer.wordpress.org/reference/classes/wp_customize_setting/_update_theme_mod/) | Deprecated method. — deprecated | 
| [WP_Customize_Setting::aggregate_multidimensional](https://developer.wordpress.org/reference/classes/wp_customize_setting/aggregate_multidimensional/) | Set up the setting for aggregated multidimensional values. | 
| [WP_Customize_Setting::check_capabilities](https://developer.wordpress.org/reference/classes/wp_customize_setting/check_capabilities/) | Validate user capabilities whether the theme supports the setting. | 
| [WP_Customize_Setting::get_root_value](https://developer.wordpress.org/reference/classes/wp_customize_setting/get_root_value/) | Get the root value for a setting, especially for multidimensional ones. | 
| [WP_Customize_Setting::id_data](https://developer.wordpress.org/reference/classes/wp_customize_setting/id_data/) | Get parsed ID data for multidimensional setting. | 
| [WP_Customize_Setting::is_current_blog_previewed](https://developer.wordpress.org/reference/classes/wp_customize_setting/is_current_blog_previewed/) | Return true if the current site is not the same as the previewed site. | 
| [WP_Customize_Setting::js_value](https://developer.wordpress.org/reference/classes/wp_customize_setting/js_value/) | Sanitize the setting’s value for use in JavaScript. | 
| [WP_Customize_Setting::json](https://developer.wordpress.org/reference/classes/wp_customize_setting/json/) | Retrieves the data to export to the client via JSON. | 
| [WP_Customize_Setting::multidimensional](https://developer.wordpress.org/reference/classes/wp_customize_setting/multidimensional/) | Multidimensional helper function. | 
| [WP_Customize_Setting::multidimensional_get](https://developer.wordpress.org/reference/classes/wp_customize_setting/multidimensional_get/) | Will attempt to fetch a specific value from a multidimensional array. | 
| [WP_Customize_Setting::multidimensional_isset](https://developer.wordpress.org/reference/classes/wp_customize_setting/multidimensional_isset/) | Will attempt to check if a specific value in a multidimensional array is set. | 
| [WP_Customize_Setting::multidimensional_replace](https://developer.wordpress.org/reference/classes/wp_customize_setting/multidimensional_replace/) | Will attempt to replace a specific value in a multidimensional array. | 
| [WP_Customize_Setting::post_value](https://developer.wordpress.org/reference/classes/wp_customize_setting/post_value/) | Fetch and sanitize the $_POST value for the setting. | 
| [WP_Customize_Setting::preview](https://developer.wordpress.org/reference/classes/wp_customize_setting/preview/) | Add filters to supply the setting’s value when accessed. | 
| [WP_Customize_Setting::sanitize](https://developer.wordpress.org/reference/classes/wp_customize_setting/sanitize/) | Sanitize an input. | 
| [WP_Customize_Setting::save](https://developer.wordpress.org/reference/classes/wp_customize_setting/save/) | Checks user capabilities and theme supports, and then saves the value of the setting. | 
| [WP_Customize_Setting::set_root_value](https://developer.wordpress.org/reference/classes/wp_customize_setting/set_root_value/) | Set the root value for a setting, especially for multidimensional ones. | 
| [WP_Customize_Setting::update](https://developer.wordpress.org/reference/classes/wp_customize_setting/update/) | Save the value of the setting, using the related API. | 
| [WP_Customize_Setting::validate](https://developer.wordpress.org/reference/classes/wp_customize_setting/validate/) | Validates an input. | 
| [WP_Customize_Setting::value](https://developer.wordpress.org/reference/classes/wp_customize_setting/value/) | Fetch the value of the setting. |

## 󠀁[Source](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#source)󠁿

    ```php
    #[AllowDynamicProperties]
    class WP_Customize_Setting {
    	/**
    	 * Customizer bootstrap instance.
    	 *
    	 * @since 3.4.0
    	 * @var WP_Customize_Manager
    	 */
    	public $manager;

    	/**
    	 * Unique string identifier for the setting.
    	 *
    	 * @since 3.4.0
    	 * @var string
    	 */
    	public $id;

    	/**
    	 * Type of customize settings.
    	 *
    	 * @since 3.4.0
    	 * @var string
    	 */
    	public $type = 'theme_mod';

    	/**
    	 * Capability required to edit this setting.
    	 *
    	 * @since 3.4.0
    	 * @var string|array
    	 */
    	public $capability = 'edit_theme_options';

    	/**
    	 * Theme features required to support the setting.
    	 *
    	 * @since 3.4.0
    	 * @var string|string[]
    	 */
    	public $theme_supports = '';

    	/**
    	 * The default value for the setting.
    	 *
    	 * @since 3.4.0
    	 * @var string
    	 */
    	public $default = '';

    	/**
    	 * Options for rendering the live preview of changes in Customizer.
    	 *
    	 * Set this value to 'postMessage' to enable a custom JavaScript handler to render changes to this setting
    	 * as opposed to reloading the whole page.
    	 *
    	 * @since 3.4.0
    	 * @var string
    	 */
    	public $transport = 'refresh';

    	/**
    	 * Server-side validation callback for the setting's value.
    	 *
    	 * @since 4.6.0
    	 * @var callable
    	 */
    	public $validate_callback = '';

    	/**
    	 * Callback to filter a Customize setting value in un-slashed form.
    	 *
    	 * @since 3.4.0
    	 * @var callable
    	 */
    	public $sanitize_callback = '';

    	/**
    	 * Callback to convert a Customize PHP setting value to a value that is JSON serializable.
    	 *
    	 * @since 3.4.0
    	 * @var callable
    	 */
    	public $sanitize_js_callback = '';

    	/**
    	 * Whether or not the setting is initially dirty when created.
    	 *
    	 * This is used to ensure that a setting will be sent from the pane to the
    	 * preview when loading the Customizer. Normally a setting only is synced to
    	 * the preview if it has been changed. This allows the setting to be sent
    	 * from the start.
    	 *
    	 * @since 4.2.0
    	 * @var bool
    	 */
    	public $dirty = false;

    	/**
    	 * ID Data.
    	 *
    	 * @since 3.4.0
    	 * @var array
    	 */
    	protected $id_data = array();

    	/**
    	 * Whether or not preview() was called.
    	 *
    	 * @since 4.4.0
    	 * @var bool
    	 */
    	protected $is_previewed = false;

    	/**
    	 * Cache of multidimensional values to improve performance.
    	 *
    	 * @since 4.4.0
    	 * @var array
    	 */
    	protected static $aggregated_multidimensionals = array();

    	/**
    	 * Whether the multidimensional setting is aggregated.
    	 *
    	 * @since 4.4.0
    	 * @var bool
    	 */
    	protected $is_multidimensional_aggregated = false;

    	/**
    	 * Constructor.
    	 *
    	 * Any supplied $args override class property defaults.
    	 *
    	 * @since 3.4.0
    	 *
    	 * @param WP_Customize_Manager $manager Customizer bootstrap instance.
    	 * @param string               $id      A specific ID of the setting.
    	 *                                      Can be a theme mod or option name.
    	 * @param array                $args    {
    	 *     Optional. Array of properties for the new Setting object. Default empty array.
    	 *
    	 *     @type string          $type                 Type of the setting. Default 'theme_mod'.
    	 *     @type string          $capability           Capability required for the setting. Default 'edit_theme_options'
    	 *     @type string|string[] $theme_supports       Theme features required to support the panel. Default is none.
    	 *     @type string          $default              Default value for the setting. Default is empty string.
    	 *     @type string          $transport            Options for rendering the live preview of changes in Customizer.
    	 *                                                 Using 'refresh' makes the change visible by reloading the whole preview.
    	 *                                                 Using 'postMessage' allows a custom JavaScript to handle live changes.
    	 *                                                 Default is 'refresh'.
    	 *     @type callable        $validate_callback    Server-side validation callback for the setting's value.
    	 *     @type callable        $sanitize_callback    Callback to filter a Customize setting value in un-slashed form.
    	 *     @type callable        $sanitize_js_callback Callback to convert a Customize PHP setting value to a value that is
    	 *                                                 JSON serializable.
    	 *     @type bool            $dirty                Whether or not the setting is initially dirty when created.
    	 * }
    	 */
    	public function __construct( $manager, $id, $args = array() ) {
    		$keys = array_keys( get_object_vars( $this ) );
    		foreach ( $keys as $key ) {
    			if ( isset( $args[ $key ] ) ) {
    				$this->$key = $args[ $key ];
    			}
    		}

    		$this->manager = $manager;
    		$this->id      = $id;

    		// Parse the ID for array keys.
    		$this->id_data['keys'] = preg_split( '/\[/', str_replace( ']', '', $this->id ) );
    		$this->id_data['base'] = array_shift( $this->id_data['keys'] );

    		// Rebuild the ID.
    		$this->id = $this->id_data['base'];
    		if ( ! empty( $this->id_data['keys'] ) ) {
    			$this->id .= '[' . implode( '][', $this->id_data['keys'] ) . ']';
    		}

    		if ( $this->validate_callback ) {
    			add_filter( "customize_validate_{$this->id}", $this->validate_callback, 10, 3 );
    		}
    		if ( $this->sanitize_callback ) {
    			add_filter( "customize_sanitize_{$this->id}", $this->sanitize_callback, 10, 2 );
    		}
    		if ( $this->sanitize_js_callback ) {
    			add_filter( "customize_sanitize_js_{$this->id}", $this->sanitize_js_callback, 10, 2 );
    		}

    		if ( 'option' === $this->type || 'theme_mod' === $this->type ) {
    			// Other setting types can opt-in to aggregate multidimensional explicitly.
    			$this->aggregate_multidimensional();

    			// Allow option settings to indicate whether they should be autoloaded.
    			if ( 'option' === $this->type && isset( $args['autoload'] ) ) {
    				self::$aggregated_multidimensionals[ $this->type ][ $this->id_data['base'] ]['autoload'] = $args['autoload'];
    			}
    		}
    	}

    	/**
    	 * Get parsed ID data for multidimensional setting.
    	 *
    	 * @since 4.4.0
    	 *
    	 * @return array {
    	 *     ID data for multidimensional setting.
    	 *
    	 *     @type string $base ID base
    	 *     @type array  $keys Keys for multidimensional array.
    	 * }
    	 */
    	final public function id_data() {
    		return $this->id_data;
    	}

    	/**
    	 * Set up the setting for aggregated multidimensional values.
    	 *
    	 * When a multidimensional setting gets aggregated, all of its preview and update
    	 * calls get combined into one call, greatly improving performance.
    	 *
    	 * @since 4.4.0
    	 */
    	protected function aggregate_multidimensional() {
    		$id_base = $this->id_data['base'];
    		if ( ! isset( self::$aggregated_multidimensionals[ $this->type ] ) ) {
    			self::$aggregated_multidimensionals[ $this->type ] = array();
    		}
    		if ( ! isset( self::$aggregated_multidimensionals[ $this->type ][ $id_base ] ) ) {
    			self::$aggregated_multidimensionals[ $this->type ][ $id_base ] = array(
    				'previewed_instances'       => array(), // Calling preview() will add the $setting to the array.
    				'preview_applied_instances' => array(), // Flags for which settings have had their values applied.
    				'root_value'                => $this->get_root_value( array() ), // Root value for initial state, manipulated by preview and update calls.
    			);
    		}

    		if ( ! empty( $this->id_data['keys'] ) ) {
    			// Note the preview-applied flag is cleared at priority 9 to ensure it is cleared before a deferred-preview runs.
    			add_action( "customize_post_value_set_{$this->id}", array( $this, '_clear_aggregated_multidimensional_preview_applied_flag' ), 9 );
    			$this->is_multidimensional_aggregated = true;
    		}
    	}

    	/**
    	 * Reset `$aggregated_multidimensionals` static variable.
    	 *
    	 * This is intended only for use by unit tests.
    	 *
    	 * @since 4.5.0
    	 * @ignore
    	 */
    	public static function reset_aggregated_multidimensionals() {
    		self::$aggregated_multidimensionals = array();
    	}

    	/**
    	 * The ID for the current site when the preview() method was called.
    	 *
    	 * @since 4.2.0
    	 * @var int
    	 */
    	protected $_previewed_blog_id;

    	/**
    	 * Return true if the current site is not the same as the previewed site.
    	 *
    	 * @since 4.2.0
    	 *
    	 * @return bool If preview() has been called.
    	 */
    	public function is_current_blog_previewed() {
    		if ( ! isset( $this->_previewed_blog_id ) ) {
    			return false;
    		}
    		return ( get_current_blog_id() === $this->_previewed_blog_id );
    	}

    	/**
    	 * Original non-previewed value stored by the preview method.
    	 *
    	 * @see WP_Customize_Setting::preview()
    	 * @since 4.1.1
    	 * @var mixed
    	 */
    	protected $_original_value;

    	/**
    	 * Add filters to supply the setting's value when accessed.
    	 *
    	 * If the setting already has a pre-existing value and there is no incoming
    	 * post value for the setting, then this method will short-circuit since
    	 * there is no change to preview.
    	 *
    	 * @since 3.4.0
    	 * @since 4.4.0 Added boolean return value.
    	 *
    	 * @return bool False when preview short-circuits due no change needing to be previewed.
    	 */
    	public function preview() {
    		if ( ! isset( $this->_previewed_blog_id ) ) {
    			$this->_previewed_blog_id = get_current_blog_id();
    		}

    		// Prevent re-previewing an already-previewed setting.
    		if ( $this->is_previewed ) {
    			return true;
    		}

    		$id_base                 = $this->id_data['base'];
    		$is_multidimensional     = ! empty( $this->id_data['keys'] );
    		$multidimensional_filter = array( $this, '_multidimensional_preview_filter' );

    		/*
    		 * Check if the setting has a pre-existing value (an isset check),
    		 * and if doesn't have any incoming post value. If both checks are true,
    		 * then the preview short-circuits because there is nothing that needs
    		 * to be previewed.
    		 */
    		$undefined     = new stdClass();
    		$needs_preview = ( $undefined !== $this->post_value( $undefined ) );
    		$value         = null;

    		// Since no post value was defined, check if we have an initial value set.
    		if ( ! $needs_preview ) {
    			if ( $this->is_multidimensional_aggregated ) {
    				$root  = self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['root_value'];
    				$value = $this->multidimensional_get( $root, $this->id_data['keys'], $undefined );
    			} else {
    				$default       = $this->default;
    				$this->default = $undefined; // Temporarily set default to undefined so we can detect if existing value is set.
    				$value         = $this->value();
    				$this->default = $default;
    			}
    			$needs_preview = ( $undefined === $value ); // Because the default needs to be supplied.
    		}

    		// If the setting does not need previewing now, defer to when it has a value to preview.
    		if ( ! $needs_preview ) {
    			if ( ! has_action( "customize_post_value_set_{$this->id}", array( $this, 'preview' ) ) ) {
    				add_action( "customize_post_value_set_{$this->id}", array( $this, 'preview' ) );
    			}
    			return false;
    		}

    		switch ( $this->type ) {
    			case 'theme_mod':
    				if ( ! $is_multidimensional ) {
    					add_filter( "theme_mod_{$id_base}", array( $this, '_preview_filter' ) );
    				} else {
    					if ( empty( self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['previewed_instances'] ) ) {
    						// Only add this filter once for this ID base.
    						add_filter( "theme_mod_{$id_base}", $multidimensional_filter );
    					}
    					self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['previewed_instances'][ $this->id ] = $this;
    				}
    				break;
    			case 'option':
    				if ( ! $is_multidimensional ) {
    					add_filter( "pre_option_{$id_base}", array( $this, '_preview_filter' ) );
    				} else {
    					if ( empty( self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['previewed_instances'] ) ) {
    						// Only add these filters once for this ID base.
    						add_filter( "option_{$id_base}", $multidimensional_filter );
    						add_filter( "default_option_{$id_base}", $multidimensional_filter );
    					}
    					self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['previewed_instances'][ $this->id ] = $this;
    				}
    				break;
    			default:
    				/**
    				 * Fires when the WP_Customize_Setting::preview() method is called for settings
    				 * not handled as theme_mods or options.
    				 *
    				 * The dynamic portion of the hook name, `$this->id`, refers to the setting ID.
    				 *
    				 * @since 3.4.0
    				 *
    				 * @param WP_Customize_Setting $setting WP_Customize_Setting instance.
    				 */
    				do_action( "customize_preview_{$this->id}", $this );

    				/**
    				 * Fires when the WP_Customize_Setting::preview() method is called for settings
    				 * not handled as theme_mods or options.
    				 *
    				 * The dynamic portion of the hook name, `$this->type`, refers to the setting type.
    				 *
    				 * @since 4.1.0
    				 *
    				 * @param WP_Customize_Setting $setting WP_Customize_Setting instance.
    				 */
    				do_action( "customize_preview_{$this->type}", $this );
    		}

    		$this->is_previewed = true;

    		return true;
    	}

    	/**
    	 * Clear out the previewed-applied flag for a multidimensional-aggregated value whenever its post value is updated.
    	 *
    	 * This ensures that the new value will get sanitized and used the next time
    	 * that `WP_Customize_Setting::_multidimensional_preview_filter()`
    	 * is called for this setting.
    	 *
    	 * @since 4.4.0
    	 *
    	 * @see WP_Customize_Manager::set_post_value()
    	 * @see WP_Customize_Setting::_multidimensional_preview_filter()
    	 */
    	final public function _clear_aggregated_multidimensional_preview_applied_flag() {
    		unset( self::$aggregated_multidimensionals[ $this->type ][ $this->id_data['base'] ]['preview_applied_instances'][ $this->id ] );
    	}

    	/**
    	 * Callback function to filter non-multidimensional theme mods and options.
    	 *
    	 * If switch_to_blog() was called after the preview() method, and the current
    	 * site is now not the same site, then this method does a no-op and returns
    	 * the original value.
    	 *
    	 * @since 3.4.0
    	 *
    	 * @param mixed $original Old value.
    	 * @return mixed New or old value.
    	 */
    	public function _preview_filter( $original ) {
    		if ( ! $this->is_current_blog_previewed() ) {
    			return $original;
    		}

    		$undefined  = new stdClass(); // Symbol hack.
    		$post_value = $this->post_value( $undefined );
    		if ( $undefined !== $post_value ) {
    			$value = $post_value;
    		} else {
    			/*
    			 * Note that we don't use $original here because preview() will
    			 * not add the filter in the first place if it has an initial value
    			 * and there is no post value.
    			 */
    			$value = $this->default;
    		}
    		return $value;
    	}

    	/**
    	 * Callback function to filter multidimensional theme mods and options.
    	 *
    	 * For all multidimensional settings of a given type, the preview filter for
    	 * the first setting previewed will be used to apply the values for the others.
    	 *
    	 * @since 4.4.0
    	 *
    	 * @see WP_Customize_Setting::$aggregated_multidimensionals
    	 * @param mixed $original Original root value.
    	 * @return mixed New or old value.
    	 */
    	final public function _multidimensional_preview_filter( $original ) {
    		if ( ! $this->is_current_blog_previewed() ) {
    			return $original;
    		}

    		$id_base = $this->id_data['base'];

    		// If no settings have been previewed yet (which should not be the case, since $this is), just pass through the original value.
    		if ( empty( self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['previewed_instances'] ) ) {
    			return $original;
    		}

    		foreach ( self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['previewed_instances'] as $previewed_setting ) {
    			// Skip applying previewed value for any settings that have already been applied.
    			if ( ! empty( self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['preview_applied_instances'][ $previewed_setting->id ] ) ) {
    				continue;
    			}

    			// Do the replacements of the posted/default sub value into the root value.
    			$value = $previewed_setting->post_value( $previewed_setting->default );
    			$root  = self::$aggregated_multidimensionals[ $previewed_setting->type ][ $id_base ]['root_value'];
    			$root  = $previewed_setting->multidimensional_replace( $root, $previewed_setting->id_data['keys'], $value );
    			self::$aggregated_multidimensionals[ $previewed_setting->type ][ $id_base ]['root_value'] = $root;

    			// Mark this setting having been applied so that it will be skipped when the filter is called again.
    			self::$aggregated_multidimensionals[ $previewed_setting->type ][ $id_base ]['preview_applied_instances'][ $previewed_setting->id ] = true;
    		}

    		return self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['root_value'];
    	}

    	/**
    	 * Checks user capabilities and theme supports, and then saves
    	 * the value of the setting.
    	 *
    	 * @since 3.4.0
    	 *
    	 * @return void|false Void on success, false if cap check fails
    	 *                    or value isn't set or is invalid.
    	 */
    	final public function save() {
    		$value = $this->post_value();

    		if ( ! $this->check_capabilities() || ! isset( $value ) ) {
    			return false;
    		}

    		$id_base = $this->id_data['base'];

    		/**
    		 * Fires when the WP_Customize_Setting::save() method is called.
    		 *
    		 * The dynamic portion of the hook name, `$id_base` refers to
    		 * the base slug of the setting name.
    		 *
    		 * @since 3.4.0
    		 *
    		 * @param WP_Customize_Setting $setting WP_Customize_Setting instance.
    		 */
    		do_action( "customize_save_{$id_base}", $this );

    		$this->update( $value );
    	}

    	/**
    	 * Fetch and sanitize the $_POST value for the setting.
    	 *
    	 * During a save request prior to save, post_value() provides the new value while value() does not.
    	 *
    	 * @since 3.4.0
    	 *
    	 * @param mixed $default_value A default value which is used as a fallback. Default null.
    	 * @return mixed The default value on failure, otherwise the sanitized and validated value.
    	 */
    	final public function post_value( $default_value = null ) {
    		return $this->manager->post_value( $this, $default_value );
    	}

    	/**
    	 * Sanitize an input.
    	 *
    	 * @since 3.4.0
    	 *
    	 * @param string|array $value The value to sanitize.
    	 * @return string|array|null|WP_Error Sanitized value, or `null`/`WP_Error` if invalid.
    	 */
    	public function sanitize( $value ) {

    		/**
    		 * Filters a Customize setting value in un-slashed form.
    		 *
    		 * @since 3.4.0
    		 *
    		 * @param mixed                $value   Value of the setting.
    		 * @param WP_Customize_Setting $setting WP_Customize_Setting instance.
    		 */
    		return apply_filters( "customize_sanitize_{$this->id}", $value, $this );
    	}

    	/**
    	 * Validates an input.
    	 *
    	 * @since 4.6.0
    	 *
    	 * @see WP_REST_Request::has_valid_params()
    	 *
    	 * @param mixed $value Value to validate.
    	 * @return true|WP_Error True if the input was validated, otherwise WP_Error.
    	 */
    	public function validate( $value ) {
    		if ( is_wp_error( $value ) ) {
    			return $value;
    		}
    		if ( is_null( $value ) ) {
    			return new WP_Error( 'invalid_value', __( 'Invalid value.' ) );
    		}

    		$validity = new WP_Error();

    		/**
    		 * Validates a Customize setting value.
    		 *
    		 * Plugins should amend the `$validity` object via its `WP_Error::add()` method.
    		 *
    		 * The dynamic portion of the hook name, `$this->ID`, refers to the setting ID.
    		 *
    		 * @since 4.6.0
    		 *
    		 * @param WP_Error             $validity Filtered from `true` to `WP_Error` when invalid.
    		 * @param mixed                $value    Value of the setting.
    		 * @param WP_Customize_Setting $setting  WP_Customize_Setting instance.
    		 */
    		$validity = apply_filters( "customize_validate_{$this->id}", $validity, $value, $this );

    		if ( is_wp_error( $validity ) && ! $validity->has_errors() ) {
    			$validity = true;
    		}
    		return $validity;
    	}

    	/**
    	 * Get the root value for a setting, especially for multidimensional ones.
    	 *
    	 * @since 4.4.0
    	 *
    	 * @param mixed $default_value Value to return if root does not exist.
    	 * @return mixed
    	 */
    	protected function get_root_value( $default_value = null ) {
    		$id_base = $this->id_data['base'];
    		if ( 'option' === $this->type ) {
    			return get_option( $id_base, $default_value );
    		} elseif ( 'theme_mod' === $this->type ) {
    			return get_theme_mod( $id_base, $default_value );
    		} else {
    			/*
    			 * Any WP_Customize_Setting subclass implementing aggregate multidimensional
    			 * will need to override this method to obtain the data from the appropriate
    			 * location.
    			 */
    			return $default_value;
    		}
    	}

    	/**
    	 * Set the root value for a setting, especially for multidimensional ones.
    	 *
    	 * @since 4.4.0
    	 *
    	 * @param mixed $value Value to set as root of multidimensional setting.
    	 * @return bool Whether the multidimensional root was updated successfully.
    	 */
    	protected function set_root_value( $value ) {
    		$id_base = $this->id_data['base'];
    		if ( 'option' === $this->type ) {
    			$autoload = true;
    			if ( isset( self::$aggregated_multidimensionals[ $this->type ][ $this->id_data['base'] ]['autoload'] ) ) {
    				$autoload = self::$aggregated_multidimensionals[ $this->type ][ $this->id_data['base'] ]['autoload'];
    			}
    			return update_option( $id_base, $value, $autoload );
    		} elseif ( 'theme_mod' === $this->type ) {
    			set_theme_mod( $id_base, $value );
    			return true;
    		} else {
    			/*
    			 * Any WP_Customize_Setting subclass implementing aggregate multidimensional
    			 * will need to override this method to obtain the data from the appropriate
    			 * location.
    			 */
    			return false;
    		}
    	}

    	/**
    	 * Save the value of the setting, using the related API.
    	 *
    	 * @since 3.4.0
    	 *
    	 * @param mixed $value The value to update.
    	 * @return bool The result of saving the value.
    	 */
    	protected function update( $value ) {
    		$id_base = $this->id_data['base'];
    		if ( 'option' === $this->type || 'theme_mod' === $this->type ) {
    			if ( ! $this->is_multidimensional_aggregated ) {
    				return $this->set_root_value( $value );
    			} else {
    				$root = self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['root_value'];
    				$root = $this->multidimensional_replace( $root, $this->id_data['keys'], $value );
    				self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['root_value'] = $root;
    				return $this->set_root_value( $root );
    			}
    		} else {
    			/**
    			 * Fires when the WP_Customize_Setting::update() method is called for settings
    			 * not handled as theme_mods or options.
    			 *
    			 * The dynamic portion of the hook name, `$this->type`, refers to the type of setting.
    			 *
    			 * @since 3.4.0
    			 *
    			 * @param mixed                $value   Value of the setting.
    			 * @param WP_Customize_Setting $setting WP_Customize_Setting instance.
    			 */
    			do_action( "customize_update_{$this->type}", $value, $this );

    			return (bool) has_action( "customize_update_{$this->type}" );
    		}
    	}

    	/**
    	 * Deprecated method.
    	 *
    	 * @since 3.4.0
    	 * @deprecated 4.4.0 Deprecated in favor of update() method.
    	 */
    	protected function _update_theme_mod() {
    		_deprecated_function( __METHOD__, '4.4.0', __CLASS__ . '::update()' );
    	}

    	/**
    	 * Deprecated method.
    	 *
    	 * @since 3.4.0
    	 * @deprecated 4.4.0 Deprecated in favor of update() method.
    	 */
    	protected function _update_option() {
    		_deprecated_function( __METHOD__, '4.4.0', __CLASS__ . '::update()' );
    	}

    	/**
    	 * Fetch the value of the setting.
    	 *
    	 * @since 3.4.0
    	 *
    	 * @return mixed The value.
    	 */
    	public function value() {
    		$id_base      = $this->id_data['base'];
    		$is_core_type = ( 'option' === $this->type || 'theme_mod' === $this->type );

    		if ( ! $is_core_type && ! $this->is_multidimensional_aggregated ) {

    			// Use post value if previewed and a post value is present.
    			if ( $this->is_previewed ) {
    				$value = $this->post_value( null );
    				if ( null !== $value ) {
    					return $value;
    				}
    			}

    			$value = $this->get_root_value( $this->default );

    			/**
    			 * Filters a Customize setting value not handled as a theme_mod or option.
    			 *
    			 * The dynamic portion of the hook name, `$id_base`, refers to
    			 * the base slug of the setting name, initialized from `$this->id_data['base']`.
    			 *
    			 * For settings handled as theme_mods or options, see those corresponding
    			 * functions for available hooks.
    			 *
    			 * @since 3.4.0
    			 * @since 4.6.0 Added the `$setting` instance as the second parameter.
    			 *
    			 * @param mixed                $default_value The setting default value. Default empty.
    			 * @param WP_Customize_Setting $setting       The setting instance.
    			 */
    			$value = apply_filters( "customize_value_{$id_base}", $value, $this );
    		} elseif ( $this->is_multidimensional_aggregated ) {
    			$root_value = self::$aggregated_multidimensionals[ $this->type ][ $id_base ]['root_value'];
    			$value      = $this->multidimensional_get( $root_value, $this->id_data['keys'], $this->default );

    			// Ensure that the post value is used if the setting is previewed, since preview filters aren't applying on cached $root_value.
    			if ( $this->is_previewed ) {
    				$value = $this->post_value( $value );
    			}
    		} else {
    			$value = $this->get_root_value( $this->default );
    		}
    		return $value;
    	}

    	/**
    	 * Sanitize the setting's value for use in JavaScript.
    	 *
    	 * @since 3.4.0
    	 *
    	 * @return mixed The requested escaped value.
    	 */
    	public function js_value() {

    		/**
    		 * Filters a Customize setting value for use in JavaScript.
    		 *
    		 * The dynamic portion of the hook name, `$this->id`, refers to the setting ID.
    		 *
    		 * @since 3.4.0
    		 *
    		 * @param mixed                $value   The setting value.
    		 * @param WP_Customize_Setting $setting WP_Customize_Setting instance.
    		 */
    		$value = apply_filters( "customize_sanitize_js_{$this->id}", $this->value(), $this );

    		if ( is_string( $value ) ) {
    			return html_entity_decode( $value, ENT_QUOTES, 'UTF-8' );
    		}

    		return $value;
    	}

    	/**
    	 * Retrieves the data to export to the client via JSON.
    	 *
    	 * @since 4.6.0
    	 *
    	 * @return array Array of parameters passed to JavaScript.
    	 */
    	public function json() {
    		return array(
    			'value'     => $this->js_value(),
    			'transport' => $this->transport,
    			'dirty'     => $this->dirty,
    			'type'      => $this->type,
    		);
    	}

    	/**
    	 * Validate user capabilities whether the theme supports the setting.
    	 *
    	 * @since 3.4.0
    	 *
    	 * @return bool False if theme doesn't support the setting or user can't change setting, otherwise true.
    	 */
    	final public function check_capabilities() {
    		if ( $this->capability && ! current_user_can( $this->capability ) ) {
    			return false;
    		}

    		if ( $this->theme_supports && ! current_theme_supports( ...(array) $this->theme_supports ) ) {
    			return false;
    		}

    		return true;
    	}

    	/**
    	 * Multidimensional helper function.
    	 *
    	 * @since 3.4.0
    	 *
    	 * @param array $root
    	 * @param array $keys
    	 * @param bool  $create Default false.
    	 * @return array|null Keys are 'root', 'node', and 'key'.
    	 */
    	final protected function multidimensional( &$root, $keys, $create = false ) {
    		if ( $create && empty( $root ) ) {
    			$root = array();
    		}

    		if ( ! isset( $root ) || empty( $keys ) ) {
    			return null;
    		}

    		$last = array_pop( $keys );
    		$node = &$root;

    		foreach ( $keys as $key ) {
    			if ( $create && ! isset( $node[ $key ] ) ) {
    				$node[ $key ] = array();
    			}

    			if ( ! is_array( $node ) || ! isset( $node[ $key ] ) ) {
    				return null;
    			}

    			$node = &$node[ $key ];
    		}

    		if ( $create ) {
    			if ( ! is_array( $node ) ) {
    				// Account for an array overriding a string or object value.
    				$node = array();
    			}
    			if ( ! isset( $node[ $last ] ) ) {
    				$node[ $last ] = array();
    			}
    		}

    		if ( ! isset( $node[ $last ] ) ) {
    			return null;
    		}

    		return array(
    			'root' => &$root,
    			'node' => &$node,
    			'key'  => $last,
    		);
    	}

    	/**
    	 * Will attempt to replace a specific value in a multidimensional array.
    	 *
    	 * @since 3.4.0
    	 *
    	 * @param array $root
    	 * @param array $keys
    	 * @param mixed $value The value to update.
    	 * @return mixed
    	 */
    	final protected function multidimensional_replace( $root, $keys, $value ) {
    		if ( ! isset( $value ) ) {
    			return $root;
    		} elseif ( empty( $keys ) ) { // If there are no keys, we're replacing the root.
    			return $value;
    		}

    		$result = $this->multidimensional( $root, $keys, true );

    		if ( isset( $result ) ) {
    			$result['node'][ $result['key'] ] = $value;
    		}

    		return $root;
    	}

    	/**
    	 * Will attempt to fetch a specific value from a multidimensional array.
    	 *
    	 * @since 3.4.0
    	 *
    	 * @param array $root
    	 * @param array $keys
    	 * @param mixed $default_value A default value which is used as a fallback. Default null.
    	 * @return mixed The requested value or the default value.
    	 */
    	final protected function multidimensional_get( $root, $keys, $default_value = null ) {
    		if ( empty( $keys ) ) { // If there are no keys, test the root.
    			return $root ?? $default_value;
    		}

    		$result = $this->multidimensional( $root, $keys );
    		return isset( $result ) ? $result['node'][ $result['key'] ] : $default_value;
    	}

    	/**
    	 * Will attempt to check if a specific value in a multidimensional array is set.
    	 *
    	 * @since 3.4.0
    	 *
    	 * @param array $root
    	 * @param array $keys
    	 * @return bool True if value is set, false if not.
    	 */
    	final protected function multidimensional_isset( $root, $keys ) {
    		$result = $this->multidimensional_get( $root, $keys );
    		return isset( $result );
    	}
    }
    ```

[View all references](https://developer.wordpress.org/reference/files/wp-includes/class-wp-customize-setting.php/)
[View on Trac](https://core.trac.wordpress.org/browser/tags/7.0/src/wp-includes/class-wp-customize-setting.php#L25)
[View on GitHub](https://github.com/WordPress/wordpress-develop/blob/7.0/src/wp-includes/class-wp-customize-setting.php#L25-L964)

## 󠀁[Related](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#related)󠁿

| Used by | Description | 
| [WP_Customize_Custom_CSS_Setting](https://developer.wordpress.org/reference/classes/wp_customize_custom_css_setting/)`wp-includes/customize/class-wp-customize-custom-css-setting.php` |

Custom Setting to handle WP Custom CSS.

  | 
| [WP_Customize_Nav_Menu_Setting](https://developer.wordpress.org/reference/classes/wp_customize_nav_menu_setting/)`wp-includes/customize/class-wp-customize-nav-menu-setting.php` |

Customize Setting to represent a nav_menu.

  | 
| [WP_Customize_Nav_Menu_Item_Setting](https://developer.wordpress.org/reference/classes/wp_customize_nav_menu_item_setting/)`wp-includes/customize/class-wp-customize-nav-menu-item-setting.php` |

Customize Setting to represent a nav_menu.

  | 
| [WP_Customize_Filter_Setting](https://developer.wordpress.org/reference/classes/wp_customize_filter_setting/)`wp-includes/customize/class-wp-customize-filter-setting.php` |

A setting that is used to filter a value, but will not save the results.

  | 
| [WP_Customize_Header_Image_Setting](https://developer.wordpress.org/reference/classes/wp_customize_header_image_setting/)`wp-includes/customize/class-wp-customize-header-image-setting.php` |

A setting that is used to filter a value, but will not save the results.

  | 
| [WP_Customize_Background_Image_Setting](https://developer.wordpress.org/reference/classes/wp_customize_background_image_setting/)`wp-includes/customize/class-wp-customize-background-image-setting.php` |

Customizer Background Image Setting class.

  |

[Show 1 more](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#)
[Show less](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#)

## 󠀁[Changelog](https://developer.wordpress.org/reference/classes/wp_customize_setting/?output_format=md#changelog)󠁿

| Version | Description | 
| [3.4.0](https://developer.wordpress.org/reference/since/3.4.0/) | Introduced. |

## User Contributed Notes

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