# Introduction

`Zend_View` is a class for working with the "view" portion of the model-view-controller pattern. That is, it exists to help keep the view script separate from the model and controller scripts. It provides a system of helpers, output filters, and variable escaping.

`Zend_View` 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.

Essentially, using `Zend_View` happens in two major steps:

1. Your controller script creates an instance of `Zend_View` and assigns variables to that instance.

2. The controller tells the `Zend_View` to render a particular view, thereby handing control over the view script, which generates the view output.

## Controller Script

As a simple example, let us say your controller has a list of book data that it wants to have rendered by a view. The controller script might look something like this:

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

    // now assign the book data to a Zend_View instance
    Zend_Loader::loadClass('Zend_View');
    $view = new Zend_View();
    $view->books = $data;

    // and render a view script called "booklist.php"
    echo $view->render('booklist.php');

## View Script

Now we need the associated view script, "booklist.php". This is a PHP script like any other, with one exception: it executes inside the scope of the `Zend_View` instance, which means that references to $this point to the `Zend_View` instance properties and methods. (Variables assigned to the instance by the controller are public properties of the `Zend_View` instance). Thus, a very basic view script could look like this:

     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><?php echo $this->escape($val['author']) ?></td>
                <td><?php echo $this->escape($val['title']) ?></td>
            </tr>
            <?php endforeach; ?>

        </table>

    <?php else: ?>

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

    <?php endif;?>

Note how we use the "escape()" method to apply output escaping to variables.

## Options

`Zend_View` has several options that may be set to configure the behaviour of your view scripts.

- `basePath`: indicate a base path from which to set the script, helper, and filter path. It assumes a directory structure of:

      base/path/
          helpers/
          filters/
          scripts/

  This may be set via `setBasePath()`, `addBasePath()`, or the `basePath` option to the constructor.

- `encoding`: indicate the character encoding to use with `htmlentities()`, `htmlspecialchars()`, and other operations. Defaults to ISO-8859-1 (latin1). May be set via `setEncoding()` or the `encoding` option to the constructor.

- `escape`: indicate a callback to be used by `escape()`. May be set via `setEscape()` or the `escape` option to the constructor.

- `filter`: indicate a filter to use after rendering a view script. May be set via `setFilter()`, `addFilter()`, or the `filter` option to the constructor.

- `strictVars:` force `Zend_View` to emit notices and warnings when uninitialized view variables are accessed. This may be set by calling `strictVars(true)` or passing the `strictVars` option to the constructor.

## Short Tags with View Scripts

In our examples and documentation, we make use of PHP short tags: `<?` and `<?=`. In addition, we typically use the alternate syntax for control structures. These are convenient shorthands to use when writing view scripts, as they make the constructs more terse, and keep statements on single lines.

That said, many developers prefer to use full tags for purposes of validation or portability. For instance, `short_open_tag` is disabled in the php.ini.recommended file, and if you template XML in view scripts, short open tags will cause the templates to fail validation.

Additionally, if you use short tags when the setting is off, then the view scripts will either cause errors or simply echo code to the user.

For this latter case, where you wish to use short tags but they are disabled, you have two options:

- Turn on short tags in your `.htaccess` file:

      php_value "short_open_tag" "on"

  This will only be possible if you are allowed to create and utilize `.htaccess` files. This directive can also be added to your `httpd.conf` file.

- Enable an optional stream wrapper to convert short tags to long tags on the fly:

      $view->setUseStreamWrapper(true);

  This registers `Zend_View_Stream` as a stream wrapper for view scripts, and will ensure that your code continues to work as if short tags were enabled.

### View Stream Wrapper Degrades Performance

Usage of the stream wrapper will degrade performance of your application, though actual benchmarks are unavailable to quantify the amount of degradation. We recommend that you either enable short tags, convert your scripts to use full tags, or have a good partial and/or full page content caching strategy in place.

## Utility Accessors

Typically, you'll only ever need to call on `assign()`, `render()`, or one of the methods for setting/adding filter, helper, and script paths. However, if you wish to extend `Zend_View` yourself, or need access to some of its internals, a number of accessors exist:

- `getVars()` will return all assigned variables.

- `clearVars()` will clear all assigned variables; useful when you wish to re-use a view object, but want to control what variables are available.

- `getScriptPath($script)` will retrieve the resolved path to a given view script.

- `getScriptPaths()` will retrieve all registered script paths.

- `getHelperPath($helper)` will retrieve the resolved path to the named helper class.

- `getHelperPaths()` will retrieve all registered helper paths.

- `getFilterPath($filter)` will retrieve the resolved path to the named filter class.

- `getFilterPaths()` will retrieve all registered filter paths.