yii2/docs/guide/view.md

View

View is an important part of MVC and is reponsible for how data is presented to the end user.

Basics

Yii uses PHP in view templates by default so in a web application a view typically contains some HTML, echo, foreach and such basic constructs. It may also contain widget calls. Using complex code in views is considered a bad practice. Such code should be moved to controller or widgets.

View is typically called from controller action like the following:

public function actionIndex()
{
	return $this->render('index', array(
		'username' => 'samdark',
	));
}

First argument is the view name. In context of the controller Yii will search for its views in views/site/ where site is controller ID. For details on how view name is resolved please refer to [yii\base\Controller::render] method. Second argument is data array that contains key-value pairs. Value is available in the view as a variable named the same as the corresponding key.

So the view for the action above should be in views/site/index.php and can be something like:

<p>Hello, <?php echo $username?>!</p>

Intead of just scalar values you can pass anything else such as arrays or objects.

Widgets

Security

One of the main security principles is to always escape output. If violated it leads to script execution and, most probably, to cross-site scripting known as XSS leading to leaking of admin passwords, making a user to automatically perform actions etc.

Yii provides a good toolset in order help you escaping your output. The very basic thing to escape is a text without any markup. You can deal with it like the following:

<?php
use yii\helpers\Html;
?>

<div class="username">
	<?php echo Html::encode($user->name); ?>
</div>

When you want to render HTML it becomes complex so we're delegating the task to excellent HTMLPurifier library. In order to use it you need to modify your composer.json first by adding the following to require:

"ezyang/htmlpurifier": "v4.5.0"

After it's done run php composer.phar install and wait till package is downloaded. Now everything is prepared to use Yii's HtmlPurifier helper:

<?php
use yii\helpers\HtmlPurifier;
?>

<div class="post">
	<?php echo HtmlPurifier::process($post->text); ?>
</div>

Note that besides HTMLPurifier does excellent job making output safe it's not very fast so consider caching result.

Alternative template languages

There are offlicial extensions for Smarty and Twig. In order to learn more refer to Using template engines section of the guide.

Using View object

An instance of yii\base\View is available in view templates as $this variable. Using it you can do many useful things including setting page title and meta, registering scripts and accessing the context.

Setting page title

A common place to set page title are view templates. Since we can access view object with $this, setting a title becomes as easy as:

$this->title = 'My page title';

Adding meta tags

Adding meta tags such as encodig, description, keywords is easy with view object as well:

$this->registerMetaTag(array('encoding' => 'utf-8'));

The first argument is an map of <meta> tag option names and values. The code above will produce:

<meta encoding="utf-8">

Sometimes there's a need to have only a single tag of a type. In this case you need to specify the second argument:

$this->registerMetaTag(array('description' => 'This is my cool website made with Yii!'), 'meta-description');
$this->registerMetaTag(array('description' => 'This website is about funny raccoons.'), 'meta-description');

If there are multiple calls with the same value of the second argument (meta-description in this case), the latter will override the former and only a single tag will be rendered:

<meta description="This website is about funny raccoons.">

Registering link tags

<link> tag is useful in many cases such as customizing favicon, ponting to RSS feed or delegating OpenID to another server. Yii view object has a method to work with these:

$this->registerLinkTag(array(
	'title' => 'Lives News for Yii Framework',
	'rel' => 'alternate',
	'type' => 'application/rss+xml',
	'href' => 'http://www.yiiframework.com/rss.xml/',
));

The code above will result in

<link title="Lives News for Yii Framework" rel="alternate" type="application/rss+xml" href="http://www.yiiframework.com/rss.xml/" />

Same as with meta tags you can specify additional argument to make sure there's only one link of a type registered.

Registering CSS

You can register CSS using registerCss or registerCssFile. Former is for outputting code in <style> tags directly to the page which is not recommended in most cases (but still valid). Latter is for registering CSS file. In Yii it's much better to use asset manager to deal with these since it provides extra features so registerCssFile is manly useful for external CSS files.

$this->registerCss("body { background: #f00; }");

The code above will result in adding the following to the head section of the page:

<style>
body { background: #f00; }
</style>

If you want to specify additional properties of the style tag, pass array of name-values to the second argument. If you need to make sure there's only a single style tag use third argument as was mentioned in meta tags description.

$this->registerCssFile("http://example.com/css/themes/black-and-white.css", array('media' => 'print'), 'css-print-theme');

The code above will add a link to CSS file to the head section of the page. The CSS will be used only when printing the page. We're using third argument so one of the views could override it.

Registering scripts

Registering asset bundles

As was mentioned earlier it's preferred to use asset bundles instead of using CSS and JavaScript directly. You can get details on how to define asset bundles in asset manager section of the guide. As for using already defined asset bundle, it's very straightforward:

frontend\config\AppAsset::register($this);

Layout

Partials

Often you need to reuse some HTML markup in many views and often it's too simple to create a full-featured widget for it. In this case you may use partials.

Partial is a view as well. It resides in one of directories under views and by convention is often started with _. For example, we need to render a list of user profiles and, at the same time, display individual profile elsewhere.

First we need to define a partial for user profile in _profile.php:

<?php
use yii\helpers\Html;
?>

<div class="profile">
	<h2><?php echo Html::encode($username); ?></h2>
	<p><?php echo Html::encode($tagline); ?></p>
</div>

Then we're using it in index.php view where we display a list of users:

<div class="user-index">
	<?php
	foreach($users as $user) {
		echo $this->render('_profile', array(
			'username' => $user->name,
			'tagline' => $user->tagline,
		));
	}
	?>
</div>

Same way we can reuse it in another view displaying a single user profile:

echo $this->render('_profile', array(
	'username' => $user->name,
	'tagline' => $user->tagline,
));

Accessing context

Views are generally used either by controller or by widget. In both cases the object that called view rendering is available in the view as $this->context. For example if we need to print out the current internal request route in a view rendered by controller we can use the following:

echo $this->context->getRoute();

Caching blocks