Question

I have a Facebook App written in PHP. Asked for user’s “email” permission. I noticed that I obtained 90% of user’s email address, but not some.

I know that the email permission allows Facebook App to get the primary email address stated in user’s profile, but why does the SDK sometimes return null?

Answer 1

“email” is an extended permission that users are not required to give when allowing an application. If you need your users to grant the “email” permission before continuing in your app, you need to check that that permission is present before allowing the user to continue his workflow after authentication.

the graph API endpoint you need to use is "/me/permissions"

Here is a method that I use to do just that:

permissions is an array of strings that represent the permissions requested.

hasPermissions(["email"], function(hasPerms){
     alert(hasPerms);
 });

function hasPermissions(permissions, callback){
    console.log("perms requested");
    console.log(permissions);
    FB.api("/me/permissions", function(response){
        var hasPerms = true;
        console.log("perms obtaind");
        console.log(response);
        for(var i in permissions){
            console.log([permissions[i]] + " - " + response["data"][0][permissions[i]])
            hasPerms = hasPerms && response["data"][0][permissions[i]] == 1;
        }
        if(typeof callback == "function"){
            callback(hasPerms);     
        }       
    });
}