Yii2中的自定义UrlRule

I ran into a problem in yii2, to make a url with some parameters, when each of them may be missed. For example:

site.com/index/param1/value1/param2/valu2/param3/value3/param4/value4

Or:

site.com/param2/value2/param4/value4

There are only 4 parameters with fixed names. I tried searching on this but didn't find appropriate documentation.

public function createUrl ($ manager, $ route, $ params)
    {
        if ($ route === 'site / index') {
            if (isset ($ params ['ship']) OR isset ($ params ['map']) OR isset ($ params ['gamemode']) OR isset ($ params ['version'])) {
                return (isset ($ params ['ship']))? $ params ['ship']. '/' ''
                . (isset ($ params ['map']))? $ params ['map']. '/' ''
                . (isset ($ params ['gamemode']))? $ params ['gamemode']. '/' ''
                . (isset ($ params ['version']))? $ params ['version']. '/', '';
            }
        }
        return false;
    }

    public function parseRequest ($ manager, $ request)
    {
        $ pathInfo = $ request-> getPathInfo ();
        if (preg_match ('% ^ (\ w +) (/ (\ w +))? $%', $ pathInfo, $ matches)) {

        }
        return false;
    }

Also, I am not able to understand what to do in parseRequest and where it is taken $params.

You can add some rules to urlManager like this:

'urlManager' => [
        'enablePrettyUrl' => true,
        'showScriptName' => false,
        'rules' => [
            ...
            'site/param1/<param1:\w+>' => 'site/action',
            'site/param2/<param2:\w+>' => 'site/action',
            'site/param3/<param3:\w+>' => 'site/action',
            'site/param4/<param4:\w+>' => 'site/action',
            'site/param1/<param1:\w+>/param2/<param2:\w+>' => 'site/action',
            'site/param1/<param1:\w+>/param3/<param3:\w+>' => 'site/action',
            'site/param1/<param1:\w+>/param4/<param4:\w+>' => 'site/action',
            'site/param2/<param2:\w+>/param3/<param3:\w+>' => 'site/action',
            'site/param2/<param2:\w+>/param4/<param4:\w+>' => 'site/action',
            'site/param3/<param3:\w+>/param4/<param4:\w+>' => 'site/action',
            'site/param1/<param1:\w+>/param2/<param2:\w+>/param3/<param3:\w+>' => 'site/action',
            'site/param1/<param1:\w+>/param2/<param2:\w+>/param4/<param4:\w+>' => 'site/action',
            'site/param1/<param1:\w+>/param3/<param3:\w+>/param4/<param4:\w+>' => 'site/action',
            'site/param2/<param2:\w+>/param3/<param3:\w+>/param4/<param4:\w+>' => 'site/action',
            'site/param1/<param1:\w+>/param2/<param2:\w+>/param3/<param3:\w+>/param4/<param4:\w+>' => 'site/action',
            ...

This might not be the most elegant way, however it still works. The main problems comes when there are more parameters.