Question

I am developing a Facebook page tab that will hold a competition.

So firstly there is the fan gate, I have implemented that easy enough with the Facebook php sdk and the signed request.

When the user gets through the fan gate I.e liked the page. There is a form with entry details.

Now I can only allow someone to enter the competition once.

So what I tried was to get the user id, but depending on the Facebook account I either get back the ID or else I get the user ID =0.

Is there any way for me to get a unique value so I can store that the user has entered the competition without having to allow access.

Answer 1

The user id is given in the signed request only if the user has given permissions to the application.