Why does the Spring Social plugin occasionally return an empty email on the User class? - facebook

Question

I have a Grails project (v2.4.2) that is making use of the spring-security-facebook:0.17 plugin to authenticate via Spring Security. At first sight, all seems well. However, there is a large set of users that for some unknown reason I cannot access their email address. I am using spring social to grab the email. I have permission and it is set in the scope. Here is a code snippet where I authenticate a new user:
log.info("Create domain for facebook user $token.uid")
//Use Spring Social Facebook to load details for current user from Facebook API
log.info("create: FacebookAuthToken: $token")
log.info("created FacebookAuthToken.FacebookAccessToken = ${token.accessToken}")
Facebook facebook = new FacebookTemplate(token.accessToken.accessToken)
org.springframework.social.facebook.api.User fbProfile = facebook.userOperations().getUserProfile()
// Check if email is actual granted because in production some are coming back null
boolean isEmailGranted=false
List<Permission> permissions = facebook?.userOperations()?.getUserPermissions()
String permissionString = "["
for (int i=0;i<permissions.size();i++) {
permissionString += "["+ permissions[i].getName() + ":" + permissions[i].getStatus()+"]"
if (permissions[i].getName()=="email" && permissions[i].isGranted())
isEmailGranted=true
}
permissionString += "]"
log.info("create: Facebook Permissions = " + permissionString)
def grailsWebRequest = WebUtils.retrieveGrailsWebRequest()
def flash = grailsWebRequest.flashScope
if (!isEmailGranted) {
log.warn("create: Unable to subscribe facebook user because email priviledge was not granted.")
flash.message = 'Login to Facebook failed. We must have access to your email address in order to proceed with login.'
throw new InsufficientAuthenticationException("Facebook email not accessible")
}
log.info("created: ")
String email = fbProfile.getEmail()
String firstName = fbProfile.getFirstName()
String lastName = fbProfile.getLastName()
String fullName = fbProfile.getName()
String username = firstName
String password = token.accessToken.accessToken
if (!email) {
log.error("create: Permission was granted to use facebook email but the value is null.")
flash.message = 'Login to Facebook failed. We are temporarily unable to access your email although permission has been granted'
throw new InsufficientAuthenticationException("Facebook email not accessible for unknown reason")
}
Why would I receive an empty email when permission has been granted? Is there a preferred method for handling this behavior (other than failing the authentication and making up a fake email address). Many thanks!

Answer 1

The documentation for the 'email' field of the 'user' object ( https://developers.facebook.com/docs/reference/api/user/ ) clarifies the expected behaviour here, which is:
"this field will not be returned if no valid email address is available"
There is a detailed explanation about different situations where an email won't be sent. Please check it out:
https://developers.facebook.com/bugs/298946933534016/
I hope it helps.