Rendering Views

The PhpRenderer

Zend\View\Renderer\PhpRenderer "renders" view scripts written in PHP, capturing and returning the output. It composes Variable containers and/or View Models, a helper plugin manager for helpers, and optional filtering of the captured output.

The PhpRenderer is template-system agnostic; you may use PHP as your template language, or create instances of other template systems and manipulate them within your view script. Anything you can do with PHP is available to you.

Usage

Basic usage consists of instantiating or otherwise obtaining an instance of the PhpRenderer, providing it with a resolver which will resolve templates to PHP view scripts, and then calling its render() method.

Instantiating a renderer:

use Zend\View\Renderer\PhpRenderer;

$renderer = new PhpRenderer();

zend-view ships with several types of "resolvers", which are used to resolve a template name to a resource a renderer can consume. The ones we will usually use with the PhpRenderer are:

• Zend\View\Resolver\TemplateMapResolver, which simply maps template names directly to view scripts.
• Zend\View\Resolver\TemplatePathStack, which creates a LIFO stack of script directories in which to search for a view script. By default, it appends the suffix .phtml to the requested template name, and then loops through the script directories; if it finds a file matching the requested template, it returns the full file path.
• Zend\View\Resolver\RelativeFallbackResolver, which allows using short template name into partial rendering. It is used as wrapper for each of two aforesaid resolvers. For example, this allows usage of partial template paths such as my/module/script/path/my-view/some/partial.phtml, while rendering template my/module/script/path/my-view by short name some/partial.
• Zend\View\Resolver\AggregateResolver, which allows attaching a FIFO queue of resolvers to consult.

We suggest using the AggregateResolver, as it allows you to create a multi-tiered strategy for resolving template names.

Programmatically, you would then do something like this:

use Zend\View\Renderer\PhpRenderer;
use Zend\View\Resolver;

$renderer = new PhpRenderer();

$resolver = new Resolver\AggregateResolver();

$renderer->setResolver($resolver);

$map = new Resolver\TemplateMapResolver([
    'layout'      => __DIR__ . '/view/layout.phtml',
    'index/index' => __DIR__ . '/view/index/index.phtml',
]);
$stack = new Resolver\TemplatePathStack([
    'script_paths' => [
        __DIR__ . '/view',
        $someOtherPath
    ],
]);

// Attach resolvers to the aggregate:
$resolver
    ->attach($map)    // this will be consulted first, and is the fastest lookup
    ->attach($stack)  // filesystem-based lookup
    ->attach(new Resolver\RelativeFallbackResolver($map)) // allow short template names
    ->attach(new Resolver\RelativeFallbackResolver($stack));

You can also specify a specific priority value when registering resolvers, with high, positive integers getting higher priority, and low, negative integers getting low priority, when resolving.

If you are started your application via the skeleton application, you can provide the above via configuration:

// In the Application module configuration
// (module/Application/config/module.config.php):
return [
    'view_manager' => [
        'template_map' => [
            'layout'      => __DIR__ . '/../view/layout.phtml',
            'index/index' => __DIR__ . '/../view/index/index.phtml',
        ],
        'template_path_stack' => [
            'application' => __DIR__ . '/../view',
        ],
    ],
];

If you did not begin with the skeleton application, you will need to write your own factories for creating each resolver and wiring them to the AggregateResolver and injecting into the PhpRenderer.

Now that we have our PhpRenderer instance, and it can find templates, let's inject some variables. This can be done in 4 different ways.

• Pass an associative array (or ArrayAccess instance, or Zend\View\Variables instance) of items as the second argument to render(): $renderer->render($templateName, ['foo' => 'bar'])
• Assign a Zend\View\Variables instance, associative array, or ArrayAccess instance to the setVars() method.
• Assign variables as instance properties of the renderer: $renderer->foo = 'bar'. This essentially proxies to an instance of Variables composed internally in the renderer by default.
• Create a ViewModel instance, assign variables to that, and pass the ViewModel to the render() method:

As an example of the latter:

use Zend\View\Model\ViewModel;
use Zend\View\Renderer\PhpRenderer;

$renderer = new PhpRenderer();

$model    = new ViewModel();
$model->setVariable('foo', 'bar');
// or
$model = new ViewModel(['foo' => 'bar']);

$model->setTemplate($templateName);
$renderer->render($model);

Now, let's render something. As an example, let us say you have a list of book data.

// use a model to get the data for book authors and titles.
$data = [
    [
        'author' => 'Hernando de Soto',
        'title' => 'The Mystery of Capitalism',
    ],
    [
        'author' => 'Henry Hazlitt',
        'title' => 'Economics in One Lesson',
    ],
    [
        'author' => 'Milton Friedman',
        'title' => 'Free to Choose',
    ],
];

// now assign the book data to a renderer instance
$renderer->books = $data;

// and render the template "booklist"
echo $renderer->render('booklist');

More often than not, you'll likely be using the MVC layer. As such, you should be thinking in terms of view models. Let's consider the following code from within an action method of a controller.

namespace Bookstore\Controller;

use Zend\Mvc\Controller\AbstractActionController;

class BookController extends AbstractActionController
{
    public function listAction()
    {
        // do some work...

        // Assume $data is the list of books from the previous example
        $model = new ViewModel(['books' => $data]);

        // Optionally specify a template; if we don't, by default it will be
        // auto-determined based on the module name, controller name and this action.
        // In this example, the template would resolve to "bookstore/book/list",
        // and thus the file "bookstore/book/list.phtml"; the following overrides
        // that to set the template to "booklist", and thus the file "booklist.phtml"
        // (note the lack of directory preceding the filename).
        $model->setTemplate('booklist');

        return $model
    }
}

This will then be rendered as if the following were executed:

$renderer->render($model);

Now we need the associated view script. At this point, we'll assume that the template booklist resolves to the file booklist.phtml. This is a PHP script like any other, with one exception: it executes inside the scope of the PhpRenderer instance, which means that references to $this point to the PhpRenderer instance properties and methods. Thus, a very basic view script could look like this:

<?php if ($this->books): ?>

    <!-- A table of some books. -->
    <table>
        <tr>
            <th>Author</th>
            <th>Title</th>
        </tr>

        <?php foreach ($this->books as $key => $val): ?>
        <tr>
            <td><?= $this->escapeHtml($val['author']) ?></td>
            <td><?= $this->escapeHtml($val['title']) ?></td>
        </tr>
        <?php endforeach; ?>

    </table>

<?php else: ?>

    <p>There are no books to display.</p>

<?php endif;?>

Escape Output

The security mantra is "Filter input, escape output." If you are unsure of the source of a given variable — which is likely most of the time — you should escape it based on which HTML context it is being injected into. The primary contexts to be aware of are HTML Body, HTML Attribute, Javascript, CSS and URI. Each context has a dedicated helper available to apply the escaping strategy most appropriate to each context. You should be aware that escaping does vary significantly between contexts; there is no one single escaping strategy that can be globally applied. In the example above, there are calls to an escapeHtml() method. The method is actually a helper, a plugin available via method overloading. Additional escape helpers provide the escapeHtmlAttr(), escapeJs(), escapeCss(), and escapeUrl() methods for each of the HTML contexts you are most likely to encounter. By using the provided helpers and being aware of your variables' contexts, you will prevent your templates from running afoul of Cross-Site Scripting (XSS) vulnerabilities.

We've now toured the basic usage of the PhpRenderer. By now you should know how to instantiate the renderer, provide it with a resolver, assign variables and/or create view models, create view scripts, and render view scripts.

Options and Configuration

Zend\View\Renderer\PhpRenderer utilizes several collaborators in order to do its work. Use the following methods to configure the renderer.

Unless otherwise noted, class names are relative to the Zend\View namespace.

setHelperPluginManager

setHelperPluginManager(string|HelperPluginManager $helpers): void

Set the helper plugin manager instance used to load, register, and retrieve helpers.

setResolver

setResolver(Resolver\\ResolverInterface $resolver) : void

Set the resolver instance.

setFilterChain

setFilterChain(\Zend\Filter\FilterChain $filters) : void

Set a filter chain to use as an output filter on rendered content.

setVars

setVars(array|\ArrayAccess|Variables $variables) : void

Set the variables to use when rendering a view script/template.

setCanRenderTrees

setCanRenderTrees(boolean $canRenderTrees) : void

Set the flag indicating whether or not we should render trees of view models. If set to true, the Zend\View\View instance will not attempt to render children separately, but instead pass the root view model directly to the PhpRenderer. It is then up to the developer to render the children from within the view script. This is typically done using the RenderChildModel helper: $this->renderChildModel('child_name').

Additional Methods

Typically, you'll only ever access variables and helpers within your view scripts or when interacting with the PhpRenderer. However, there are a few additional methods you may be interested in.

Unless otherwise noted, class names are relative to the Zend\View namespace.

render

render(
    string|Model\ModelInterface $nameOrModel,
    array|\Traversable $values = null
) : string

Render a template/view model.

If $nameOrModel is a string, it is assumed to be a template name. That template will be resolved using the current resolver, and then rendered.

If $values is non-null, those values, and those values only, will be used during rendering, and will replace whatever variable container previously was in the renderer; however, the previous variable container will be reset when done.

If $values is empty, the current variables container (see setVars()) will be injected when rendering.

If $nameOrModel is a ModelInterface instance, the template name will be retrieved from it and used. Additionally, if the model contains any variables, these will be used when rendering; otherwise, the variables container already present, if any, will be used.

The method returns the script output.

resolver

resolver() : Resolver\ResolverInterface

Retrieves the current Resolver instance.

vars

vars(string $key = null) : mixed

Retrieve a single variable from the container if a key is provided; otherwise it will return the variables container.

plugin

plugin(string $name, array $options = null) : Helper\HelperInterface

Retrieve a plugin/helper instance. Proxies to the plugin manager's get() method; as such, any $options you pass will be passed to the plugin's constructor if this is the first time the plugin has been retrieved. See the section on helpers for more information.

addTemplate

addTemplate(string $template) : void

Add a template to the stack. When used, the next call to render() will loop through all templates added using this method, rendering them one by one; the output of the last will be returned.