Symfony switch language - php

Question

I use symfony 1.4.11 .User can switch language , in my layout I have
<?php foreach (sfConfig::get('app_cultures_enabled') as $key => $lng): ?>
<?php echo link_to_if($sf_user->getCulture() != $lng,
"<img src=\"/images/flags/$lng.png\" alt=\"$lng\">",
preg_replace('/sf_culture=[a-z][a-z]/', 'sf_culture='.$lng, $sf_context->getRouting()->getCurrentInternalUri(true)))?>
<?php endforeach ?>
So in each page I generate link, that I can switch language.
But I have page with next rout:
page:
url: /:sf_culture/page/:slug
param: { module: page, action: show}
requirements: { sf_culture: (?:se|no|en), sf_method: GET }
And when I go to this page I have error, that :
The "/:sf_culture/page/:slug" route has some missing mandatory parameters (:slug).
I think that problem in
<?php echo link_to_if($sf_user->getCulture() != $lng,
"<img src=\"/images/flags/$lng.png\" alt=\"$lng\">",
preg_replace('/sf_culture=[a-z][a-z]/', 'sf_culture='.$lng, $sf_context->getRouting()->getCurrentInternalUri(true)))?>
it can not generate link with slug, or..

Answer 1

If I'm reading this right, it looks like you're trying to mimick the slug variable using $sf_context->getRouting()->getCurrentInternalUri(true).
I've never done a language switch link this way but basically if that works, you need to pass it as a variable called "slug" to the routing. Somewhere in that magical link_to_if() function you need to have:
'&slug=' . $slug // the slug!
... given that slug is a named parameter that the routing rule is expecting.
UPDATE:
This is how I'd normally change language:
I'd create a separate action (e.g. changeLanguage) without a template, and then create links to it with the language as a parameter:
mysite.com/change-language/fr/ (?lang=fr)
mysite.com/change-language/de/ (?lang=de)
mysite.com/change-language/es/ (?lang=es)
In that action, I use $this->getUser()->setCulture($lang) to change language and anything else I want to do, and then use $this->redirect($request->getReferer()) to redirect the user back to the page they came from. If your app needs to use multi-language URLs, I would ensure that those get rendered on their own pages from a URL parameter (like the "slug"). And if you're doing this with SEO in mind, things also get a little more complicated because you should link directly to different language pages instead of using re-directs etc (to pass link juice).
Hope that helps.