How to add custom variable in url without redirect?

Question

I'm trying to add a local variable to my URL.

As an example I have this URL:

mysite.com/my-page-name/

And I want to add 'en' variable into it and leave the page working properly:

mysite.com/en/my-page-name/ 

I tried to deal with it using add_rewrite_tag() and add_rewrite_rule() but it isn't working so what am I doing wrong?

add_rewrite_tag('%locale%', '^([a-z]{2})');
add_rewrite_rule('^([a-z]{2})/(.+)[/$]', 'index.php?pagename=$matches[2]', 'top');

Answer 1

There are various ways to achieve it. The most simplest one could be to make a new page and with name "en" so the slug will be mysite.com/en/

Now make the "en" page as parent of my-page-name or in other words make my-page-name as a child of en. So slug will be mysite.com/en/my-page-name/

Answer 2

It was just a mistake in regexp in rewrite rule. This one works perfectly!

add_rewrite_rule('^([a-z]{2})\/(.+)(\/)?$', 'index.php?page=&pagename=$matches[2]&locale=$matches[1]', 'top');