Customize: Ensure that a setting (especially a multidimensional one) can still be previewed when the post value to preview is set after `preview()` is invoked.

* Introduce `customize_post_value_set_{$setting_id}` and `customize_post_value_set` actions which are done when `WP_Customize_Manager::set_post_value()` is called.
* Clear the `preview_applied` flag for aggregated multidimensional settings when a post value is set. This ensures the new value is used instead of a previously-cached previewed value.
* Move `$is_preview` property from subclasses to `WP_Customize_Setting` parent class.
* Deferred preview: Ensure that when `preview()` short-circuits due to not being applicable that it will be called again later when the post value is set.
* Populate post value for updated-widget with the (unsanitized) JS-value in `WP_Customize_Widgets::call_widget_update()` so that value will be properly sanitized when accessed in `WP_Customize_Manager::post_value()`.

Includes unit tests with assertions to check the reported issues and validate the fixes.

Fixes defect introduced in [35007].
See #32103.
Fixes #34738.

Built from https://develop.svn.wordpress.org/trunk@35724


git-svn-id: http://core.svn.wordpress.org/trunk@35688 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-customize-manager.php

@@ -659,6 +659,36 @@ final class WP_Customize_Manager {
 	public function set_post_value( $setting_id, $value ) {
 		$this->unsanitized_post_values();
 		$this->_post_values[ $setting_id ] = $value;
+
+		/**
+		 * Announce when a specific setting's unsanitized post value has been set.
+		 *
+		 * Fires when the {@see WP_Customize_Manager::set_post_value()} method is called.
+		 *
+		 * The dynamic portion of the hook name, `$setting_id`, refers to the setting ID.
+		 *
+		 * @since 4.4.0
+		 *
+		 * @param mixed                $value Unsanitized setting post value.
+		 * @param WP_Customize_Manager $this  WP_Customize_Manager instance.
+		 */
+		do_action( "customize_post_value_set_{$setting_id}", $value, $this );
+
+		/**
+		 * Announce when any setting's unsanitized post value has been set.
+		 *
+		 * Fires when the {@see WP_Customize_Manager::set_post_value()} method is called.
+		 *
+		 * This is useful for <code>WP_Customize_Setting</code> instances to watch
+		 * in order to update a cached previewed value.
+		 *
+		 * @since 4.4.0
+		 *
+		 * @param string               $setting_id Setting ID.
+		 * @param mixed                $value      Unsanitized setting post value.
+		 * @param WP_Customize_Manager $this       WP_Customize_Manager instance.
+		 */
+		do_action( 'customize_post_value_set', $setting_id, $value, $this );
 	}
 
 	/**

wp-includes/class-wp-customize-setting.php

@@ -81,6 +81,15 @@ class WP_Customize_Setting {
 	 */
 	protected $id_data = array();
 
+	/**
+	 * Whether or not preview() was called.
+	 *
+	 * @since 4.4.0
+	 * @access protected
+	 * @var bool
+	 */
+	protected $is_previewed = false;
+
 	/**
 	 * Cache of multidimensional values to improve performance.
 	 *
@@ -191,6 +200,8 @@ class WP_Customize_Setting {
 		}
 
 		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;
 		}
 	}
@@ -245,6 +256,12 @@ class WP_Customize_Setting {
 		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' );
@@ -273,7 +290,11 @@ class WP_Customize_Setting {
 			$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;
 		}
 
@@ -327,9 +348,28 @@ class WP_Customize_Setting {
 				 */
 				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 <code>WP_Customize_Setting::_multidimensional_preview_filter()</code>
+	 * is called for this setting.
+	 *
+	 * @since 4.4.0
+	 * @access private
+	 * @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'][ $this->id ] );
+	}
+
 	/**
 	 * Callback function to filter non-multidimensional theme mods and options.
 	 *
@@ -369,13 +409,13 @@ class WP_Customize_Setting {
 	 * the first setting previewed will be used to apply the values for the others.
 	 *
 	 * @since 4.4.0
-	 * @access public
+	 * @access private
 	 *
 	 * @see WP_Customize_Setting::$aggregated_multidimensionals
 	 * @param mixed $original Original root value.
 	 * @return mixed New or old value.
 	 */
-	public function _multidimensional_preview_filter( $original ) {
+	final public function _multidimensional_preview_filter( $original ) {
 		if ( ! $this->is_current_blog_previewed() ) {
 			return $original;
 		}

wp-includes/class-wp-customize-widgets.php

@@ -1380,7 +1380,7 @@ final class WP_Customize_Widgets {
 		 * in place from WP_Customize_Setting::preview() will use this value
 		 * instead of the default widget instance value (an empty array).
 		 */
-		$this->manager->set_post_value( $setting_id, $instance );
+		$this->manager->set_post_value( $setting_id, $this->sanitize_widget_js_instance( $instance ) );
 
 		// Obtain the widget control with the updated instance in place.
 		ob_start();

wp-includes/customize/class-wp-customize-nav-menu-item-setting.php

@@ -119,15 +119,6 @@ class WP_Customize_Nav_Menu_Item_Setting extends WP_Customize_Setting {
 	 */
 	public $original_nav_menu_term_id;
 
-	/**
-	 * Whether or not preview() was called.
-	 *
-	 * @since 4.3.0
-	 * @access protected
-	 * @var bool
-	 */
-	protected $is_previewed = false;
-
 	/**
 	 * Whether or not update() was called.
 	 *

wp-includes/customize/class-wp-customize-nav-menu-setting.php

@@ -88,15 +88,6 @@ class WP_Customize_Nav_Menu_Setting extends WP_Customize_Setting {
 	 */
 	public $previous_term_id;
 
-	/**
-	 * Whether or not preview() was called.
-	 *
-	 * @since 4.3.0
-	 * @access protected
-	 * @var bool
-	 */
-	protected $is_previewed = false;
-
 	/**
 	 * Whether or not update() was called.
 	 *

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.4-beta4-35723';
+$wp_version = '4.4-beta4-35724';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.