I wrote a little commerce 2 price adjuster that works fine if i place it in /vendor/craftcms/commerce/src/adjusters/FriendsDiscountAdjuster.php and register it manually in /vendor/craftcms/commerce/src/services/OrderAdjustments.php

However, i wanted to port it to a plugin, but i do fail registering the adjuster to commerce.

I placed the adjuster in my vendor/pluginName/src/adjusters/ folder and added it to my plugin.

It fails with: Cannot declare class craft\commerce\adjusters\FriendsDiscountAdjuster, because the name is already in use

this is my main plugin file Friendsdiscount.php:

namespace hendrikeng\friendsdiscount;

use Craft;
use craft\base\Plugin;
use craft\services\Plugins;
use craft\events\PluginEvent;
use craft\commerce\services\OrderAdjustments;
use craft\events\RegisterComponentTypesEvent;
use hendrikeng\friendsdiscount\adjusters\FriendsDiscountAdjuster;

use yii\base\Event;

class Friendsdiscount extends Plugin
    public static $plugin;

    public $schemaVersion = '1.0.0';

    public function init()
        self::$plugin = $this;

            function(RegisterComponentTypesEvent $event) {
                $event->types[] = FriendsDiscountAdjuster::class;

the src/adjusters/FriendDiscountAdjuster.php:


namespace craft\commerce\adjusters;

use Craft;
use craft\commerce\base\AdjusterInterface;
use craft\commerce\elements\Order;
use craft\commerce\models\OrderAdjustment;
use craft\commerce\Plugin;

class FriendsDiscountAdjuster implements AdjusterInterface
  // ...Adjust something

1 Answer 1


the adjuster had the wrong namespace, changing it to:

namespace hendrikeng\friendsdiscount\adjusters

fixed the issue

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