Facebook: Access list of my friends' friends

how can i get a list of my friends friends in Facebook using any Facebook API?

I've seen this working on some Facebook apps - like the Marketplace app that allows to search for ads from my friends and their friends.

How do they do it? However, I'm getting stuck with FQL here:

"SELECT uid2 FROM friend WH开发者_如何学GoERE uid1 in ( select uid2 from friend where uid1 = {0} )"

because facebook tells me:

Can't lookup all friends of XXXX; can only lookup for the logged in user (YYYY) or for pairs of users

(where XXXX would be the first user ID returned by the subselect and YYYY is my user ID)

So, can anyone tell me, what's the trick to get this working?

It's not possible to get Friend's Friends. It has not been allowed via the API for years.

I think that the only way to browse the friend's friend's graph is that both of them gave permissions to your application. In that case you can rebuit the graph and scroll it until the second level.