country is getting appended twice in storefront URL(spartacus) - spartacus-storefront

Question

I'm having trouble with the basesite service. We currently have three websites: global, cn (China), and tw (Taiwan) (Taiwan)
To pick the region, we have a drop-down menu on the global site. Using baseservice(spartacus), the selected region is set.
this.baseSiteService.setActive(region);
localhost:4200/cn/cn When the above line has run, appears in the URL
Could someone please explain how it is appended twice in the url and how to override this?

Answer 1

You said in the comment that you "don't have any services or configs related to site context". So I guess what you see in the URL by default are 2 different site contexts: baseSite and language, which "by coincidence" have the same values pairwise):
localhost:4200/<baseSite>/<language>
I guess what you want to achieve in this case is to have an URL of the shape localhost:4200/<baseSite>. This can be achieved in 2 ways, depending on whether you're using static or automatic site-context configuration.
You can configure which site contexts should appear in the URL in 2 ways:
if you're using CMS-driven site context configuration in Spartacus (aka. automatic site-context-configuration), then you need to configure it in CMS Backoffice tool. As in the screenshot below, for each of your basesites go to WCMS -> Website -> <select your base site> -> Administration (tab) -> URL Encoding Attributes and put there only the value storefront (get rid of language or anything else there). And save the changes.
if you're using static site-context configuration in Spartacus, then you need to provide the following static config in your app:
provideConfig({
urlParameters: ['baseSite']
})
References:
Automatic Site Configuration Detection from URL (demo video)
Spartacus docs on Site-context configuration