Facebook targeted application – Ask for user email before or after social connect?
I created an app that does some automation using Facebook groups but I'm having a small issue with my registration/login workflow. The app requires the users' Facebook user_managed_groups permission to do it's work so I opted to have the user login/register with Facebook and OAuth and there is no other way to get access to my app. The issue I ran into is that Facebook does not always return the user email address in some cases (privacy, SMS signup).
Reading this and this tell me that a Facebook only login is not a great idea, but my application is literally useless without Facebook so I think in my case this Facebook login is required (please feel free to dispute this if I'm missing something).
I would like a valid user email address on system, but now I'm torn on whether to offer a pre-registration with email address only or do it after the Facebook login/registration?
Thinking things through if I have users pre-register to give their email address they would have the following steps:
- Register
- Wait for email then confirm email address
- Connect their Facebook
On the other hand with Facebook registration they would simply connect their Facebook and go on their merry way. The only problem I see with the second flow is if there is no email on file and I ask for it then it would have to be confirmed before I could send them emails.
I'm very new to this so I feel like I'm missing something. What is the best way to handle this Facebook null email exception?