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Hook

LUYA has a built in hooking mechanism which allows you to print code in various sections. The luya\Hook class is similar to Yii events.

Let´s assume we have a layout file with a section output which is used sometimes but could be blank as well:

php
<html>
<head>
    <title>Page</title>
</head>
<body>
    <nav>
    ...
    </nav>
    
    <?= $content; ?>
    
    <footer>
        <?= Hook::string('layoutFooter'); ?>
    </footer>
</body>
</html>

Hooks setup

Now a hooking listener is setup which is listening to the identifier layoutFooter. After setting up the hook listener, the luya\Hook can be filled with content from various files like blocks, controllers or widgets.

Let´s assume we have a controller with an action:

php
class DefaultController extends \luya\web\Controller
{
    public function actionIndex()
    {
        Hook::on('layoutFooter', function($hook) {
            return 'Output from the Hook.';
        });
    
        return $this->render('index');
    } 
}

You can also provide an array instead of a callable function in order to have a more structured object oriented way:

php
class DefaultController extends \luya\web\Controller
{
    public function actionIndex()
    {
        Hook::on('layoutFooter', [$this, 'footerHook']);
    
        return $this->render('index');
    } 
    
    public function footerHook($hook)
    {
        // do something
        return $this->renderPartial('_footerHook', []);
    }
}

If luya\Hook::on() is called multiple times in a request cycle the output will concated and sorted by execution time.

Using array output

Sometimes it is more convenient to iterate elements instead of concant the output. This can be helpful e.g. if you are working with list outputs:

php
Hook::on('fooBarArray', function($hook) {
    $hook[] = 'Hello';
    $hook[] = 'World';
});
Hook::on('fooBarArray', function($hook) {
    $hook[] = 'Hola';
    $hook[] = 'LUYA!';
});

As the luya\Hook::iterate() method can be called multiple times the hook iteration array contains now 4 elements which can be rendered as following:

php
<ul>
    <?php foreach (Hook::iterate('fooBarArray') as $item): ?>
        <li>
            <?= $item; ?>
        </li>
    <?php endforeach; ?>
</ul>

The rendered output for the iteration example:

html
<ul>
    <li>Hello</li>
    <li>World</li>
    <li>Hola</li>
    <li>LUYA!</li>
</ul>

It´s also possible to use associated arrays with keys:

php
Hook::on('fooBarArrayLinks', function($hook) {
    $hook['https://luya.io'] = 'LUYA Website';
    $hook['https://github.com'] = 'GitHub';
});

When using array keys multiple times the last executed item will override the former key.

php
<ul>
    <?php foreach (Hook::iterate('fooBarArrayLinks') as $url => $name): ?>
        <li>
            <a href="<?= $url; ?>"><?= $name; ?></a>
        </li>
    <?php endforeach; ?>
</ul>

The rendered output for the iteration example:

html
<ul>
    <li><a href="https://luya.io">LUYA Website<a/></li>
    <li><a href="https://github.com">GitHub</a></li>
</ul>