Using flash messages in YII

When you are editing a model with a form, when you are deleting a model, or doing any
other operation, it is good to tell users if it went fine or if there was an error. Typically, after
some kind of action, such as editing a form, a redirect will happen and we need to display a
message on the page we want to go to. However, how to pass it from the current page to the
redirect target and clean afterwards? Flash messages will help us.
Getting ready
Set up a new application using yiic webapp.
How to do it...
1. Let's create a protected/controllers/WebsiteController.php controller
as follows:
class WebsiteController extends CController
{
function actionOk()
{
Yii::app()->user->setFlash('success', 'Everything went
fine!');
$this->redirect('index');
}
function actionBad()
{
Yii::app()->user->setFlash('error', 'Everything went
wrong!');
$this->redirect('index');
}
function actionIndex()
{
$this->render('index');
}
}
2. Additionally, create the protected/views/website/index.php view as follows:
<?php if(Yii::app()->user->hasFlash('success')):?>
<div class="flash-notice">
<?php echo Yii::app()->user->getFlash('success')?>
</div>
<?php endif?>
<?php if(Yii::app()->user->hasFlash('error')):?>
<div class="flash-error">
<?php echo Yii::app()->user->getFlash('error')?>
</div>
<?php endif?>
3. Now, if we go to http://example.com/website/ok, we'll be redirected to
http://example.com/website/index and a success message will be displayed.
Moreover, if we go to http://example.com/website/bad, we will be redirected
to the same page, but with an error message. Refreshing the index page will hide
the message.
How it works...
We are setting a flash message with Yii::app()->user->setFlash('success',
'Everything went fine!'), for example, calling CWebUser::setFlash. Internally,
it is saving a message into a user state, so in the lowest level, our message is being kept in
$_SESSION until Yii::app()->user->getFlash('success') is called and the
$_SESSION key is deleted.