widgets\ActiveForm validate()

Validates one or several models and returns an error message array indexed by the attribute IDs.

This is a helper method that simplifies the way of writing AJAX validation code.

For example, you may use the following code in a controller action to respond to an AJAX validation request:

$model = new Post;
$model->load(Yii::$app->request->post());
if (Yii::$app->request->isAjax) {
    Yii::$app->response->format = Response::FORMAT_JSON;
    return ActiveForm::validate($model);
}
// ... respond to non-AJAX request ...

To validate multiple models, simply pass each model as a parameter to this method, like the following:

ActiveForm::validate($model1, $model2, ...);