Can some one explain Event rules in plugins

Question

So here is what I see in a controller:

 $event->rules['cpActionTrigger1'] = 'plugin/default/do-something';

What does the first part 'cpActionTrigger1' refer to and what does the second part refer to. I am guessing route and template but never see it spelled out in docs.

Answer 1

This looks like it’d be in a closure registered on the UrlManager::EVENT_REGISTER_CP_URL_RULES event, like this:

Event::on(
    UrlManager::class,
    UrlManager::EVENT_REGISTER_CP_URL_RULES,
    function (RegisterUrlRulesEvent $e) {
        $e->rules['my/route'] => 'module/controller/action';
    });

The above explains it almost in context—when creating a route with a plain string, it's interpreted as:

<module-id>/<controller-name>/<action-name>

The "Module ID" is either defined by the Plugin in question, or when you declare modules in app.php:

<?php

return [
    '*' => [
        // Lots of other irrelevant (but important) stuff redacted, here!
        'modules' => [
            'bizniz' => \modules\mymodule\BusinessStuff::class,
        ],
     ],
];

If you had a Controller in your Module (and have properly declared BusinessStuff::$controllerNamespace) that looked like this…

<?php

namespace modules\mymodule\controllers;

use craft\base\Controller;

class FinanceController extends Controller
{
    public function actionCountBeans()
    {
        return $this->asJson(['profit' => (rand() / getrandmax()) * 1000000]);
    }
}

…your "action path" would be bizniz/finance/count-beans. Yii takes care of mapping the path to your controller—and the UrlManager ensures the key you assign it to acts as an alias.