/**
		 * Begin of custom development
		 */
		$value = new stdClass();
		$value->id = 7;
		$value->value = $_POST['article_classes'];

		$currentValues = json_decode($article->get('extra_fields'));
		//If no previous Value
		if(empty($currentValues) || !is_array($currentValues)) {
			$currentValues = array();
			$currentValues[] = $value;
		} else {
			foreach ($currentValues as $key => $oneValue) {
				if($oneValue->id == 7) {
					$currentValues[$key] = $value;
				}
			}
		}

		$article->set('extra_fields', json_encode($currentValues)); 
		/**
		 * End of custom development
		 */

$value = new stdClass();
		$value->id = 7;
		$value->value = $_POST['article_classes'];

		$currentValues = json_decode($vars['var1']-->get('extra_fields'));
		//If no previous Value
		if(empty($currentValues) || !is_array($currentValues)) {
			$currentValues = array();
			$currentValues[] = $value;
		} else {
			foreach ($currentValues as $key => $oneValue) {
				if($oneValue->id == 7) {
					$currentValues[$key] = $value;
				}
			}
		}

        $vars['var2']->set('extra_fields', json_encode($currentValues));