ExpressionEngine Docs

Developing Variable Modifiers

Add-ons can provide their own variable modifiers for use in templates.

Each variable modifier needs be created as a separate file in the Modifiers directory within the add-on’s root folder, and registered in addon.setup.php.

The file name, which is also the PHP class name, should be the modifier’s name with the first letter capitalized.

All modifier files are required to implement ExpressionEngine\Service\Template\Variables\ModifierInterface.

Each modifier should have a namespace definition, which consists of the add-on’s namespace as defined in addon.setup.php followed by \Modifiers.

Lastly, the modifier’s name should be registered in addon.setup.php.

Tip: Modifiers provided by add-ons can be called by their name as well as by their name prefixed with add-on’s name and underscore. For example, below we can use {title:hacker} and {title:seeo_hacker} to achieve the same result.


Let’s create the :hacker modifier, which would make text look geeky by converting some of the letters to similar looking numbers. This example modifier is part of the “Seeo” add-on.


* namespace is required and must be add-on's namespace + 'Modifiers'
namespace EEHarbor\Seeo\Modifiers;

use ExpressionEngine\Service\Template\Variables\ModifierInterface;

class Hacker implements ModifierInterface
    public function modify($data, $params = array(), $tagdata = false)
        return str_replace(['e', 'o', 'l'], ['3', '0', '1'], (string) $data);

Next, we’ll add the following to addon.setup.php

'modifiers' => array(

And now, let’s call it in a template.

{exp:channel:entries entry_id="1"}
    <div class="title">
        <span>{title}</span> - Hello
    <div class="hacker">
        <span>{title:hacker}</span> - H3110
    <div class="seeo_hacker">
        <span>{title:seeo_hacker}</span> - H3110