How to get email and username when Facebook registers -

as far know, on new facebook api, there no way facebook username. also, if user registered facebook, or account might lack email address if or logged in phone number.

however, working on project, where, upon login facebook, if user not have user, facebook login interpreted registration. since, according best knowledge, there no way facebook username using api, using email field generate username, taking account letters.

however, in cases, username generated way duplicated, or facebook account not have email address. best solution can think redirect user form or can enter email and/or username, not user-experience.

is there way gather these data without making user enter them? or close it?

first of all, should present data want store user before store it, , let him change it.

that being said, (app scoped) id thing unique, can either use email directly (if user registered, add facebook id database) , present input field if there no email - or generate username first , last name. present chosen username user , let him change it, or tell him exists.

after all, wouldn´t user want choose username?

if want make smooth user , don´t want bug him in anyway, can store facebook id. or use email directly username (including @ sign , domain), wrote above. if that´s not enough, need implement own routine auto-generate usernames. there´s no general logic facebook this.