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Using Views

Views represent the user interface of your application. Views are often HTML files with embedded PHP code that perform tasks related solely to the presentation of the data. Views handle the job of providing data to the web browser or other tool that is used to make requests from your application.

The Phalcon\Mvc\View and Phalcon\Mvc\View\Simple are responsible for the managing the view layer of your MVC application.

Integrating Views with Controllers

Phalcon automatically passes the execution to the view component as soon as a particular controller has completed its cycle. The view component will look in the views folder for a folder named as the same name of the last controller executed and then for a file named as the last action executed. For instance, if a request is made to the URL http://127.0.0.1/blog/posts/show/301, Phalcon will parse the URL as follows:

Server Address 127.0.0.1
Phalcon Directory blog
Controller posts
Action show
Parameter 301

The dispatcher will look for a “PostsController” and its action “showAction”. A simple controller file for this example:

<?php

class PostsController extends \Phalcon\Mvc\Controller
{

    public function indexAction()
    {

    }

    public function showAction($postId)
    {
        // Pass the $postId parameter to the view
        $this->view->setVar("postId", $postId);
    }

}

The setVar allows us to create view variables on demand so that they can be used in the view template. The example above demonstrates how to pass the $postId parameter to the respective view template.

Hierarchical Rendering

Phalcon\Mvc\View supports a hierarchy of files and is the default component for view rendering in Phalcon. This hierarchy allows for common layout points (commonly used views), as well as controller named folders defining respective view templates.

This component uses by default PHP itself as the template engine, therefore views should have the .phtml extension. If the views directory is app/views then view component will find automatically for these 3 view files.

Name File Description
Action View app/views/posts/show.phtml This is the view related to the action. It only will be shown when the “show” action was executed.
Controller Layout app/views/layouts/posts.phtml This is the view related to the controller. It only will be shown for every action executed within the controller “posts”. All the code implemented in the layout will be reused for all the actions in this controller.
Main Layout app/views/index.phtml This is main action it will be shown for every controller or action executed within the application.

You are not required to implement all of the files mentioned above. Phalcon\Mvc\View will simply move to the next view level in the hierarchy of files. If all three view files are implemented, they will be processed as follows:

<!-- app/views/posts/show.phtml -->

<h3>This is show view!</h3>

<p>I have received the parameter <?php echo $postId ?></p>
<!-- app/views/layouts/posts.phtml -->

<h2>This is the "posts" controller layout!</h2>

<?php echo $this->getContent() ?>
<!-- app/views/index.phtml -->
<html>
    <head>
        <title>Example</title>
    </head>
    <body>

        <h1>This is main layout!</h1>

        <?php echo $this->getContent() ?>

    </body>
</html>

Note the lines where the method $this->getContent() was called. This method instructs Phalcon\Mvc\View on where to inject the contents of the previous view executed in the hierarchy. For the example above, the output will be:

../_images/views-1.png

The generated HTML by the request will be:

<!-- app/views/index.phtml -->
<html>
    <head>
        <title>Example</title>
    </head>
    <body>

        <h1>This is main layout!</h1>

        <!-- app/views/layouts/posts.phtml -->

        <h2>This is the "posts" controller layout!</h2>

        <!-- app/views/posts/show.phtml -->

        <h3>This is show view!</h3>

        <p>I have received the parameter 101</p>

    </body>
</html>

Using Templates

Templates are views that can be used to share common view code. They act as controller layouts, so you need to place them in the layouts directory.

<?php

class PostsController extends \Phalcon\Mvc\Controller
{
    public function initialize()
    {
        $this->view->setTemplateAfter('common');
    }

    public function lastAction()
    {
        $this->flash->notice("These are the latest posts");
    }
}
<!-- app/views/index.phtml -->
<!DOCTYPE html>
<html>
    <head>
        <title>Blog's title</title>
    </head>
    <body>
        <?php echo $this->getContent() ?>
    </body>
</html>
<!-- app/views/layouts/common.phtml -->

<ul class="menu">
    <li><a href="/">Home</a></li>
    <li><a href="/articles">Articles</a></li>
    <li><a href="/contact">Contact us</a></li>
</ul>

<div class="content"><?php echo $this->getContent() ?></div>
<!-- app/views/layouts/posts.phtml -->

<h1>Blog Title</h1>

<?php echo $this->getContent() ?>
<!-- app/views/posts/last.phtml -->

<article>
    <h2>This is a title</h2>
    <p>This is the post content</p>
</article>

<article>
    <h2>This is another title</h2>
    <p>This is another post content</p>
</article>

The final output will be the following:

<!-- app/views/index.phtml -->
<!DOCTYPE html>
<html>
    <head>
        <title>Blog's title</title>
    </head>
    <body>

        <!-- app/views/layouts/common.phtml -->

        <ul class="menu">
            <li><a href="/">Home</a></li>
            <li><a href="/articles">Articles</a></li>
            <li><a href="/contact">Contact us</a></li>
        </ul>

        <div class="content">

            <!-- app/views/layouts/posts.phtml -->

            <h1>Blog Title</h1>

            <!-- app/views/posts/last.phtml -->

            <article>
                <h2>This is a title</h2>
                <p>This is the post content</p>
            </article>

            <article>
                <h2>This is another title</h2>
                <p>This is another post content</p>
            </article>

        </div>

    </body>
</html>

Control Rendering Levels

As seen above, Phalcon\Mvc\View supports a view hierarchy. You might need to control the level of rendering produced by the view component. The method PhalconMvc\View::setRenderLevel() offers this functionality.

This method can be invoked from the controller or from a superior view layer to interfere with the rendering process.

<?php

use Phalcon\Mvc\Controller,
    Phalcon\Mvc\View;

class PostsController extends Controller
{

    public function indexAction()
    {

    }

    public function findAction()
    {

        // This is an Ajax response so it doesn't generate any kind of view
        $this->view->setRenderLevel(View::LEVEL_NO_RENDER);

        //...
    }

    public function showAction($postId)
    {
        // Shows only the view related to the action
        $this->view->setRenderLevel(View::LEVEL_ACTION_VIEW);
    }

}

The available render levels are:

Class Constant Description Order
LEVEL_NO_RENDER Indicates to avoid generating any kind of presentation.  
LEVEL_ACTION_VIEW Generates the presentation to the view associated to the action. 1
LEVEL_BEFORE_TEMPLATE Generates presentation templates prior to the controller layout. 2
LEVEL_LAYOUT Generates the presentation to the controller layout. 3
LEVEL_AFTER_TEMPLATE Generates the presentation to the templates after the controller layout. 4
LEVEL_MAIN_LAYOUT Generates the presentation to the main layout. File views/index.phtml 5

Disabling render levels

You can permanently or temporarily disable render levels. A level could be permanently disabled if it isn’t used at all in the whole application:

<?php

use Phalcon\Mvc\View;

$di->set('view', function(){

    $view = new View();

    //Disable several levels
    $view->disableLevel(array(
        View::LEVEL_LAYOUT => true,
        View::LEVEL_MAIN_LAYOUT => true
    ));

    return $view;

}, true);

Or disable temporarily in some part of the application:

<?php

use Phalcon\Mvc\View,
    Phalcon\Mvc\Controller;

class PostsController extends Controller
{

    public function indexAction()
    {

    }

    public function findAction()
    {
        $this->view->disableLevel(View::LEVEL_MAIN_LAYOUT);
    }

}

Picking Views

As mentioned above, when Phalcon\Mvc\View is managed by Phalcon\Mvc\Application the view rendered is the one related with the last controller and action executed. You could override this by using the Phalcon\Mvc\View::pick() method:

<?php

class ProductsController extends \Phalcon\Mvc\Controller
{

    public function listAction()
    {
        // Pick "views-dir/products/search" as view to render
        $this->view->pick("products/search");

        // Pick "views-dir/books/list" as view to render
        $this->view->pick(array('books'));

        // Pick "views-dir/products/search" as view to render
        $this->view->pick(array(1 => 'search'));
    }
}

Disabling the view

If your controller doesn’t produce any output in the view (or not even have one) you may disable the view component avoiding unnecessary processing:

<?php

class UsersController extends \Phalcon\Mvc\Controller
{

    public function closeSessionAction()
    {
        //Close session
        //...

        //An HTTP Redirect
        $this->response->redirect('index/index');

        //Disable the view to avoid rendering
        $this->view->disable();
    }

}

You can return a ‘response’ object to avoid disable the view manually:

<?php

class UsersController extends \Phalcon\Mvc\Controller
{

    public function closeSessionAction()
    {
        //Close session
        //...

        //An HTTP Redirect
        return $this->response->redirect('index/index');
    }

}

Simple Rendering

Phalcon\Mvc\View\Simple is an alternative component to Phalcon\Mvc\View. It keeps most of the philosophy of Phalcon\Mvc\View but lacks of a hierarchy of files which is, in fact, the main feature of its counterpart.

This component allows the developer to have control of when a view is rendered and its location. In addition, this component can leverage of view inheritance available in template engines such as Volt and others.

The default component must be replaced in the service container:

<?php

$di->set('view', function() {

    $view = new Phalcon\Mvc\View\Simple();

    $view->setViewsDir('../app/views/');

    return $view;

}, true);

Automatic rendering must be disabled in Phalcon\Mvc\Application (if needed):

<?php

try {

    $application = new Phalcon\Mvc\Application($di);

    $application->useImplicitView(false);

    echo $application->handle()->getContent();

} catch (\Exception $e) {
    echo $e->getMessage();
}

To render a view it’s necessary to call the render method explicitly indicating the relative path to the view you want to display:

<?php

class PostsController extends \Phalcon\Mvc\Controller
{

    public function indexAction()
    {
        //Render 'views-dir/index.phtml'
        echo $this->view->render('index');

        //Render 'views-dir/posts/show.phtml'
        echo $this->view->render('posts/show');

        //Render 'views-dir/index.phtml' passing variables
        echo $this->view->render('index', array('posts' => Posts::find()));

        //Render 'views-dir/posts/show.phtml' passing variables
        echo $this->view->render('posts/show', array('posts' => Posts::find()));
    }

}

Using Partials

Partial templates are another way of breaking the rendering process into simpler more manageable chunks that can be reused by different parts of the application. With a partial, you can move the code for rendering a particular piece of a response to its own file.

One way to use partials is to treat them as the equivalent of subroutines: as a way to move details out of a view so that your code can be more easily understood. For example, you might have a view that looks like this:

<div class="top"><?php $this->partial("shared/ad_banner") ?></div>

<div class="content">
    <h1>Robots</h1>

    <p>Check out our specials for robots:</p>
    ...
</div>

<div class="footer"><?php $this->partial("shared/footer") ?></div>

Method partial() does accept a second parameter as an array of variables/parameters that only will exists in the scope of the partial:

<?php $this->partial("shared/ad_banner", array('id' => $site->id, 'size' => 'big')) ?>

Transfer values from the controller to views

Phalcon\Mvc\View is available in each controller using the view variable ($this->view). You can use that object to set variables directly to the view from a controller action by using the setVar() method.

<?php

class PostsController extends \Phalcon\Mvc\Controller
{

    public function indexAction()
    {

    }

    public function showAction()
    {
        //Pass all the posts to the views
        $this->view->setVar("posts", Posts::find());

        //Using the magic setter
        $this->view->posts = Posts::find();

        //Passing more than one variable at the same time
        $this->view->setVars(array(
            'title' => $post->title,
            'content' => $post->content
        ));
    }

}

A variable with the name of the first parameter of setVar() will be created in the view, ready to be used. The variable can be of any type, from a simple string, integer etc. variable to a more complex structure such as array, collection etc.

<div class="post">
<?php

  foreach ($posts as $post) {
    echo "<h1>", $post->title, "</h1>";
  }

?>
</div>

Using models in the view layer

Application models are always available at the view layer. The Phalcon\Loader will instantiate them at runtime automatically:

<div class="categories">
<?php

    foreach (Categories::find("status = 1") as $category) {
       echo "<span class='category'>", $category->name, "</span>";
    }

?>
</div>

Although you may perform model manipulation operations such as insert() or update() in the view layer, it is not recommended since it is not possible to forward the execution flow to another controller in the case of an error or an exception.

Caching View Fragments

Sometimes when you develop dynamic websites and some areas of them are not updated very often, the output is exactly the same between requests. Phalcon\Mvc\View offers caching a part or the whole rendered output to increase performance.

Phalcon\Mvc\View integrates with Phalcon\Cache to provide an easier way to cache output fragments. You could manually set the cache handler or set a global handler:

<?php

class PostsController extends \Phalcon\Mvc\Controller
{

    public function showAction()
    {
        //Cache the view using the default settings
        $this->view->cache(true);
    }

    public function showArticleAction()
    {
        // Cache this view for 1 hour
        $this->view->cache(array(
            "lifetime" => 3600
        ));
    }

    public function resumeAction()
    {
        //Cache this view for 1 day with the key "resume-cache"
        $this->view->cache(
            array(
                "lifetime" => 86400,
                "key"      => "resume-cache",
            )
        );
    }

    public function downloadAction()
    {
        //Passing a custom service
        $this->view->cache(
            array(
                "service"  => "myCache",
                "lifetime" => 86400,
                "key"      => "resume-cache",
            )
        );
    }

}

When we do not define a key to the cache, the component automatically creates one using a md5 hash of the name of the view currently being rendered. It is a good practice to define a key for each action so you can easily identify the cache associated with each view.

When the View component needs to cache something it will request a cache service from the services container. The service name convention for this service is “viewCache”:

<?php

use Phalcon\Cache\Frontend\Output as OutputFrontend,
    Phalcon\Cache\Backend\Memcache as MemcacheBackend;

//Set the views cache service
$di->set('viewCache', function() {

    //Cache data for one day by default
    $frontCache = new OutputFrontend(array(
        "lifetime" => 86400
    ));

    //Memcached connection settings
    $cache = new MemcacheBackend($frontCache, array(
        "host" => "localhost",
        "port" => "11211"
    ));

    return $cache;
});
The frontend must always be Phalcon\Cache\Frontend\Output and the service ‘viewCache’ must be registered as always open (not shared) in the services container (DI)

When using views, caching can be used to prevent controllers from needing to generate view data on each request.

To achieve this we must identify uniquely each cache with a key. First we verify that the cache does not exist or has expired to make the calculations/queries to display data in the view:

<?php

class DownloadController extends \Phalcon\Mvc\Controller
{

    public function indexAction()
    {

        //Check whether the cache with key "downloads" exists or has expired
        if ($this->view->getCache()->exists('downloads')) {

            //Query the latest downloads
            $latest = Downloads::find(array(
                'order' => 'created_at DESC'
            ));

            $this->view->latest = $latest;
        }

        //Enable the cache with the same key "downloads"
        $this->view->cache(array(
            'key' => 'downloads'
        ));
    }

}

The PHP alternative site is an example of implementing the caching of fragments.

Template Engines

Template Engines help designers to create views without the use of a complicated syntax. Phalcon includes a powerful and fast templating engine called Volt.

Additionally, Phalcon\Mvc\View allows you to use other template engines instead of plain PHP or Volt.

Using a different template engine, usually requires complex text parsing using external PHP libraries in order to generate the final output for the user. This usually increases the number of resources that your application will use.

If an external template engine is used, Phalcon\Mvc\View provides exactly the same view hierarchy and it’s still possible to access the API inside these templates with a little more effort.

This component uses adapters, these help Phalcon to speak with those external template engines in a unified way, let’s see how to do that integration.

Creating your own Template Engine Adapter

There are many template engines, which you might want to integrate or create one of your own. The first step to start using an external template engine is create an adapter for it.

A template engine adapter is a class that acts as bridge between Phalcon\Mvc\View and the template engine itself. Usually it only needs two methods implemented: __construct() and render(). The first one receives the Phalcon\Mvc\View instance that creates the engine adapter and the DI container used by the application.

The method render() accepts an absolute path to the view file and the view parameters set using $this->view->setVar(). You could read or require it when it’s necessary.

<?php

class MyTemplateAdapter extends \Phalcon\Mvc\View\Engine
{

    /**
     * Adapter constructor
     *
     * @param \Phalcon\Mvc\View $view
     * @param \Phalcon\DI $di
     */
    public function __construct($view, $di)
    {
        //Initialize here the adapter
        parent::__construct($view, $di);
    }

    /**
     * Renders a view using the template engine
     *
     * @param string $path
     * @param array $params
     */
    public function render($path, $params)
    {

        // Access view
        $view = $this->_view;

        // Access options
        $options = $this->_options;

        //Render the view
        //...
    }

}

Changing the Template Engine

You can replace or add more a template engine from the controller as follows:

<?php

class PostsController extends \Phalcon\Mvc\Controller
{

    public function indexAction()
    {
        // Set the engine
        $this->view->registerEngines(
            array(
                ".my-html" => "MyTemplateAdapter"
            )
        );
    }

    public function showAction()
    {
        // Using more than one template engine
        $this->view->registerEngines(
            array(
                ".my-html" => 'MyTemplateAdapter',
                ".phtml" => 'Phalcon\Mvc\View\Engine\Php'
            )
        );
    }

}

You can replace the template engine completely or use more than one template engine at the same time. The method Phalcon\Mvc\View::registerEngines() accepts an array containing data that define the template engines. The key of each engine is an extension that aids in distinguishing one from another. Template files related to the particular engine must have those extensions.

The order that the template engines are defined with Phalcon\Mvc\View::registerEngines() defines the relevance of execution. If Phalcon\Mvc\View finds two views with the same name but different extensions, it will only render the first one.

If you want to register a template engine or a set of them for each request in the application. You could register it when the view service is created:

<?php

//Setting up the view component
$di->set('view', function() {

    $view = new \Phalcon\Mvc\View();

    //A trailing directory separator is required
    $view->setViewsDir('../app/views/');

    $view->registerEngines(array(
        ".my-html" => 'MyTemplateAdapter'
    ));

    return $view;

}, true);

There are adapters available for several template engines on the Phalcon Incubator

Injecting services in View

Every view executed is included inside a Phalcon\DI\Injectable instance, providing easy access to the application’s service container.

The following example shows how to write a jQuery ajax request using a url with the framework conventions. The service “url” (usually Phalcon\Mvc\Url) is injected in the view by accessing a property with the same name:

<script type="text/javascript">

$.ajax({
    url: "<?php echo $this->url->get("cities/get") ?>"
})
.done(function() {
    alert("Done!");
});

</script>

Stand-Alone Component

All the components in Phalcon can be used as glue components individually because they are loosely coupled to each other:

Hierarchical Rendering

Using Phalcon\Mvc\View in a stand-alone mode can be demonstrated below

<?php

$view = new \Phalcon\Mvc\View();

//A trailing directory separator is required
$view->setViewsDir("../app/views/");

// Passing variables to the views, these will be created as local variables
$view->setVar("someProducts", $products);
$view->setVar("someFeatureEnabled", true);

//Start the output buffering
$view->start();

//Render all the view hierarchy related to the view products/list.phtml
$view->render("products", "list");

//Finish the output buffering
$view->finish();

echo $view->getContent();

A short syntax is also available:

<?php

$view = new \Phalcon\Mvc\View();

echo $view->getRender('products', 'list',
    array(
        "someProducts" => $products,
        "someFeatureEnabled" => true
    ),
    function($view) {
        //Set any extra options here
        $view->setViewsDir("../app/views/");
        $view->setRenderLevel(Phalcon\Mvc\View::LEVEL_LAYOUT);
    }
);

Simple Rendering

Using Phalcon\Mvc\View\Simple in a stand-alone mode can be demonstrated below:

<?php

$view = new \Phalcon\Mvc\View\Simple();

//A trailing directory separator is required
$view->setViewsDir("../app/views/");

// Render a view and return its contents as a string
echo $view->render("templates/welcomeMail");

// Render a view passing parameters
echo $view->render("templates/welcomeMail", array(
    'email' => $email,
    'content' => $content
));

View Events

Phalcon\Mvc\View and Phalcon\Mvc\View\Simple are able to send events to an EventsManager if it is present. Events are triggered using the type “view”. Some events when returning boolean false could stop the active operation. The following events are supported:

Event Name Triggered Can stop operation?
beforeRender Triggered before starting the render process Yes
beforeRenderView Triggered before rendering an existing view Yes
afterRenderView Triggered after rendering an existing view No
afterRender Triggered after completing the render process No
notFoundView Triggered when a view was not found No

The following example demonstrates how to attach listeners to this component:

<?php

$di->set('view', function() {

    //Create an events manager
    $eventsManager = new Phalcon\Events\Manager();

    //Attach a listener for type "view"
    $eventsManager->attach("view", function($event, $view) {
        echo $event->getType(), ' - ', $view->getActiveRenderPath(), PHP_EOL;
    });

    $view = new \Phalcon\Mvc\View();
    $view->setViewsDir("../app/views/");

    //Bind the eventsManager to the view component
    $view->setEventsManager($eventsManager);

    return $view;

}, true);

The following example shows how to create a plugin that clean/repair the HTML produced by the render process using Tidy:

<?php

class TidyPlugin
{

    public function afterRender($event, $view)
    {

        $tidyConfig = array(
            'clean' => true,
            'output-xhtml' => true,
            'show-body-only' => true,
            'wrap' => 0,
        );

        $tidy = tidy_parse_string($view->getContent(), $tidyConfig, 'UTF8');
        $tidy->cleanRepair();

        $view->setContent((string) $tidy);
    }

}

//Attach the plugin as a listener
$eventsManager->attach("view:afterRender", new TidyPlugin());