How to merge route parameters in MenuBuidler for language switcher functionality using KnpMenuBundle and Symfony3

Introduction

In my personal project I am using:

• XAMPP with PHP v7.1.6
• Symfony v3.3.6
• KnpMnenuBundle dev-master / 2.2.x-dev [link 1], [link 2], [link 3] in order to manage Menus.
• Bootstrap v3.3.7
• Bootstrap and KnpMenuBundle integration [link 4]

Setting up

To setup i used documentation in [2], [3] and code samples [4]. My menu is working, integration between Bootstrap and KnpMenuBundle also works.

Problem

In order to implement language switcher, i am using twig templates.

It works fine, but i would like to move to more scalable approach - namely - using dedicated bundle (KnpMenuBundle).

At the moment MenuBuilder produces ugly URLs (shown in results section of code sample 1). I would like it to generate links that are shown in results section of code sample 2.

I do not know how to achieve that.

Question

How can one produce pretty URLs using MenuBuilder?

How can one force merging of route parameters in MenuBuilder?

CODE: sample 1

sample of my MenuBuilder

$language['Language']->setChildrenAttribute("class", "dropdown-menu")
    ->addChild('Language LV', array('label' => 'language.lv', 'route' => 'homepage_lv', 'routeParameters' => array('_locale' => 'lv')))
    ->setExtra('translation_domain', 'language');
$language['Language']->setChildrenAttribute("class", "dropdown-menu")
    ->addChild('Language EN', array('label' => 'language.en', 'route' => 'homepage_en', 'routeParameters' => array('_locale' => 'en')))
    ->setExtra('translation_domain', 'language');
$language['Language']->setChildrenAttribute("class", "dropdown-menu")
    ->addChild('Language RU', array('label' => 'language.ru', 'route' => 'homepage_ru', 'routeParameters' => array('_locale' => 'ru')))
    ->setExtra('translation_domain', 'language');

produces following links:

• http://127.0.0.1:8000/lv/?_locale=lv
• http://127.0.0.1:8000/en/?_locale=en
• http://127.0.0.1:8000/ru/?_locale=ru

locale change does not occurs

CODE: sample 2

conventional Menu twig template

<li><a href="{{ path(current_route, app.request.get('_route_params') | merge({'_locale': 'lv'})) }}">{{ "language.lv" | trans({}, "language") }}</a></li>
<li><a href="{{ path(current_route, app.request.get('_route_params') | merge({'_locale': 'en'})) }}">{{ "language.en" | trans({}, "language") }}</a></li>
<li><a href="{{ path(current_route, app.request.get('_route_params') | merge({'_locale': 'ru'})) }}">{{ "language.ru" | trans({}, "language") }}</a></li>

produces following links:

• http://127.0.0.1:8000/lv/home
• http://127.0.0.1:8000/en/home
• http://127.0.0.1:8000/ru/home

actually changes locale after clicking on them

CODE: sample 3

relevant part of my routing.yml file

# redirecting home
homepage:
    path: /
    defaults:
        _controller: 'FrameworkBundle:Redirect:redirect'
        route: home
        permanent: true

# redirecting home
homepage_lv:
    path: /lv/
    defaults:
        _controller: 'FrameworkBundle:Redirect:redirect'
        route: home
        permanent: true

# redirecting home
homepage_en:
    path: /en/
    defaults:
        _controller: 'FrameworkBundle:Redirect:redirect'
        route: home
        permanent: true

# redirecting home
homepage_ru:
    path: /ru/
    defaults:
        _controller: 'FrameworkBundle:Redirect:redirect'
        route: home
        permanent: true

home:
    path:     /{_locale}/home
    defaults: { _controller: 'AppBundle:Home:home' }
    requirements:
        _locale: lv|en|ru

Conclusion

Please advise.

Thank you for your time and knowledge.

So it looks like, that routes with parameters in MenuBuilder (as opposed to routes in twig templates) does not handle redirects in routing.yml

That means that correct syntax for my case is:

$language['Language']->setChildrenAttribute("class", "dropdown-menu")
    ->addChild('Language LV', array('label' => 'language.lv', 'route' => 'home', 'routeParameters' => array('_locale' => 'lv')))
    ->setExtra('translation_domain', 'language');
$language['Language']->setChildrenAttribute("class", "dropdown-menu")
    ->addChild('Language EN', array('label' => 'language.en', 'route' => 'home', 'routeParameters' => array('_locale' => 'en')))
    ->setExtra('translation_domain', 'language');
$language['Language']->setChildrenAttribute("class", "dropdown-menu")
    ->addChild('Language RU', array('label' => 'language.ru', 'route' => 'home', 'routeParameters' => array('_locale' => 'ru')))
    ->setExtra('translation_domain', 'language');

And it results in pretty URLs.