Facebook Messenger Platform: how to get user specific information?

Question

I'm trying the recent released Facebook Messenger Platform and so far so good. Everything worked well and I was able to create a echo bot.

But I'm wondering how I could identify this user that started chatting in my page. For example, when a user started chatting I get a PID user (page specific user id).

Making the follow request to Facebook Graph API:

GET https://graph.facebook.com/v2.6/{PAGE_SPECIFIC_USER_ID}

I discovered that I can just ask for the following fields: first_name,last_name and profile_pic.

So my question is, how could I discover if this user is a current customer of my business page? Is there another way of querying more information (like e-mail and real facebook user id)?

Answer 1

Facebook has updated the messenger platform API (2016-07-01) and introduced a new feature called Account Linking. This can be used to identify a user who has created an account on your website via Facebook Login and you can link the two accounts. Facebook login has its own set of permissions which can be used to get a lot more information via Facebook graph API. You can find the complete list here.