How do I create a custom Twig extension which includes third party code?

Question

I found several solutions to build a dynamic, complex navigation in craft. One is described here: Adding active class to globally cached navigation. Now i would like to create a more powerfull twig filter for creating different navigation and breadcrumb types with selecting of active links. I already wrote some test code in plain php and used for this the library simplehtmldom (helper for changing dom elements in php like in jquery). A demonstration about what i want to do can be found here: http://www.bahu.ch/craft/. Now i started with creating the twig filter, but i can't include the library in my plugin. Here is a quick overview of my plugin code.

   <?php 
   namespace Craft;
   use Twig_Extension;

   use Twig_Filter_Method;

Now i need to include the library (i know, that the next line is incorrect)

   include('simple_html_dom.php');

   class k4NavigationTwigExtension extends \Twig_Extension

   {


public function getName()
{
    return 'k4Navigation';
}

public function getFilters()
{
    return array(
        'k4Navigation' => new Twig_Filter_Method($this, 'k4Navigation'),
    );
}

public function k4Navigation($navigation)
{

    $html = str_get_html($navigation);

on the next line the current url should replace the string "test.html"

    $selectElem = $html->find('a[href="test.html"]')[0];

    if (is_object($selectElem)){
       // loop li and set class active
        for ($i = 1; $i <= 20; $i++) {
            $selectElem->setAttribute("class","active");
            $selectElem =  $selectElem->parent();
            if (!is_object($selectElem)){
                break;
            }
        }    
    }

    return $html;

   }

   }

Maybe someone can give me a hint, how to includ the library and the first example? You can download the full test code and started plugin from here: https://github.com/tombauer/k4-navigation

Many thanks for any help!

Sunny regards Tom

Answer 1

In your plugins main file add the following:

public function addTwigExtension()
{
    Craft::import('plugins.myplugin.twigextensions.myTwigExtension');

    return new MyTwigExtension();
}

In your plugin folder, add a new folder called 'twigextensions'.

In the new 'twigextensions' folder, add your twig filter 'MyTwigExtension.php'.

<?php

namespace Craft;

use Twig_Extension;
use Twig_Filter_Method;

class MyTwigExtension extends \Twig_Extension
{

    public function getName()
    {
        return 'My Twig Extension';
    }

    public function getFilters()
    {
        $returnArray = array();
        $methods = array(
            'myfilter',
        );

        foreach ($methods as $methodName) {
            $returnArray[$methodName] = new \Twig_Filter_Method($this, $methodName);
        }

        return $returnArray;
    }

    public function myfilter($content)
    {
        // perform filter operations

        return "My Filter Result";
    }

}

You can thank Luke Holder's twig extension craft-inflect for this!

Answer 2

Douglas McDonald's answer is correct with one issue though. The import statement is actually case sensitive

Craft::import('plugins.myplugin.twigextensions.MyTwigExtension');

I also have 2 additional notes:

• The getName() method is deprecated so you shouldn't bother with it
• The getFilters() method can be written much shorter, for example:

public function getFilters()
{
    return [
        'myfilter' => new \Twig_Filter_Method($this, 'myfilter'),
    ];
}