ProcessWire - Hooks

Wie funktionieren Hooks

https://processwire.com/docs/modules/hooks/

Hier in Kürze die wichtigsten Infos.

Alle Klassen die von Wire abstammen können Hookable Methoden implementieren..

Beginnt eine Funktion in der Klasse mit 3 Underscores wird Sie automatisch Hookable.

public function ___hookableMethod($arg1, $arg2) {
  // this method is hookable
}

Aufgerufen wird die Funktion ohne die Underscores

'''
$this->hookableMethod('a', 'b');

Mit einer Hook-Funktion kann man folgendes anstellen:

• Argumente für die Funktion holen oder modifizieren bevor sie verarbeitet werden (beforeHook)
• Den Rückgabewert der Funktion holen und/oder modifizieren nachdem die Argumente verarbeitet wurden (afterHook)
• Die Methode komplett ersetzen (Variante des beforeHook)
• Eine Methode in die Klasse einschleusen. Diese ist dann über $object->method() verfügbar.
• Eine Eigenschaft in die Klasse einschleusen. Diese ist dann über $object->property verfügbar. Das funktioniert nicht bei allen Hooks.

Wo setzt man hooks am Besten ein

Es gibt einige Standard Dateien die für solche Zwecke geeignet sind:

/site/init.php

PW Boot -> Module mit autoload -> init.php

This file is included during ProcessWire's boot initialization, immediately after autoload modules have been loaded and had their init() methods called. Anything you do in here will behave the same as an init() method on a module. When this file is called, the current $page has not yet been determined. This is an excellent place to attach hooks that don't need to know anything about the current page.

/site/ready.php

API geladen und ready -> $page bereit aber noch nicht gerendert

This file is included immediately after the API is fully ready. It behaves the same as a ready() method in an autoload module. The current $page has been determined, but not yet rendered. This is an excellent place to attach hooks that may need to know something about the current page. It's also an excellent place to include additional classes or libraries that will be used on all pages in your site.

/site/finished.php

Seite gerendert

This file is included when ProcessWire has finished rendering and delivering a page, and is in the process of shutting down. It is called immediately before the API is disengaged, so you can still access any API variable and update $session values as needed. Admittedly, this is probably not the place you would put hooks, but it is an ideal place to perform your own shutdown, should your application call for it.

Beispiele für Hooks

Basic Starter Hook

Erster Schritt zum ausprobieren

// i.e. in ready.php
$wire->addHookAfter('Pages::saved', function(HookEvent $event) {
  $page = $event->arguments(0);
  bd($page); // tracy debugger output
});

// more specific
$wire->addHookAfter('Pages::added(template=basic-page)', function(HookEvent $event) {
  $page = $event->arguments(0);
  bd($page);
});

Feld manipulieren

Beim Speichern einer Seite ein Feld anpassen

$pages->addHookAfter('saveReady', function(HookEvent $event) {
    $page = $event->arguments(0);
    // If the page has the relevant template...
    if($page->template == 'oe') {
        // make title uppercase
        $page->name = strtoupper($page->name);
    }
});

Seiten im Backend sortieren

/*sort clients of key account manager by title in backend*/
$pages->addHookAfter('saveReady', function(HookEvent $event) {
    $page = $event->arguments(0);
    // If the page has the relevant template...
    if($page->template == 'key_account_manager') {
        // Sort the Page Reference field by title
        $page->pr_kam_clients->sort('title') ;
    }
});

Externe Klasse verfügbar machen

/site/ready.php

<?php

$pages->addHookAfter('saved', function($event) {
  $page = $event->object;
  if($page->template == 'product') {
    // update other related pages when 'product' page is saved
  }
});

if($page->template != 'admin') {
  // include an external helper class...
  require('./classes/ProductCart.php');
  // ...and establish it as a new $cart API variable, and
  // populate it with products saved in the user's session:
  $wire->wire('cart', new ProductCart($session->productsInCart));
}

There is also a /site/finished.php that obtains the products from the $cart and saves them back to the session, ready for the next request:

/site/finished.php

<?php

if($page->template != 'admin') {
  $session->productsInCart = $cart->getArray();
}

Custom Hook Methode

Beispiel aus der ready.php

/** @var ProcessWire $wire */

/**
 * Example of a custom hook method
 * 
 * This hook adds a “numPosts” method to pages using template “category”.
 * The return value is the quantity of posts in category.
 *
 * Usage:
 * ~~~~~
 * $numPosts = $page->numPosts(); // returns integer
 * numPosts = $page->numPosts(true); // returns string like "5 posts"
 * ~~~~~
 *
 */
$wire->addHook('Page(template=category)::numPosts', function($event) {
	/** @var Page $page */
	$page = $event->object;

	// only category pages have numPosts
	if($page->template != 'category') return;

	// find number of posts
	$numPosts = $event->pages->count("template=blog-post, categories=$page");

	if($event->arguments(0) === true) {
		// if true argument was specified, format it as a "5 posts" type string
		$numPosts = sprintf(_n('%d post', '%d posts', $numPosts), $numPosts);
	}

	$event->return = $numPosts;
});

Rendering von Formularen anpassen

Manchmal rendern Module Formulare im Frontend, aber die Styles passen nicht ganz zum eigenen Style. Man kann aber vor dem Rendern des Formulars einhaken und noch ein paar Klassen nachschieben bevor es gerendert wird. Die Hookfunktion kann man in ready.php unterbringen. Also kurz bevor ProcessWire mit dem Rendern der Seite loslegt.

ready.php

/**
 * add uikit classes to checkout forms
 */
  $this->addHookBefore('InputfieldForm::render', function(HookEvent $event) {
    if(page()->template->name == 'checkout'){
        // Get the object the event occurred on
        $InputfieldForm = $event->object;
        foreach($InputfieldForm as $f){
            bd(get_class($f),'Inputfield Hook->field');
            switch (get_class($f)) {
                case 'ProcessWire\InputfieldEmail':
                case 'ProcessWire\InputfieldText':
                    $f->addClass('uk-input');
                    break;
                case 'ProcessWire\InputfieldTextarea':
                    $f->addClass('uk-textarea');
                    break;
                case 'ProcessWire\InputfieldRadios':
                    $f->addClass('uk-radio');
                    break;
                case 'ProcessWire\InputfieldCheckbox':
                    $f->addClass('uk-checkbox');
                    break;
                case 'ProcessWire\InputfieldSubmit':
                    $f->addClass('uk-button uk-button-primary');
                    break;
            }
            

        }
        return $InputfieldForm; // send back manipulated object
    }
  });