cant get email with Net::Facebook::Oauth2 - perl

Question

my $fb = Net::Facebook::Oauth2->new(
application_id => 'your_application_id',
application_secret => 'your_application_secret',
callback => 'http://yourdomain.com/facebook/callback'
);
my $access_token = $fb->get_access_token(code => $cgi->param('code'));
###save this token in database or session
##later on your application you can use this verifier code to comunicate
##with facebook on behalf of this user
my $fb = Net::Facebook::Oauth2->new(
access_token => $access_token
);
my $info = $fb->get(
'https://graph.facebook.com/me' ##Facebook API URL
);
print $info->as_json;
when i try to print the json format of response i am missing the email the followin is the output what i get
{"id":"100001199655561","name":"Pavan Kumar Tummalapalli","first_name":"Pavan","middle_name":"Kumar","last_name":"Tummalapalli","link":"http:\/\/www.facebook.com\/pavan.tummalapalli","username":"pavan.tummalapalli","hometown":{"id":"125303864178019","name":"Kodada, India"},"location":{"id":"115200305158163","name":"Hyderabad, Andhra Pradesh"},"favorite_athletes":[{"id":"108661895824433","name":"AB de Villiers"}],"education":[{"school":{"id":"129163957118653","name":"City Central School"},"type":"High School"},{"school":{"id":"124833707555779","name":"Anurag Engineering College"},"year":{"id":"136328419721520","name":"2009"},"type":"College"}],"gender":"male","timezone":5.5,"locale":"en_US","verified":true,"updated_time":"2012-12-30T09:13:54+0000"}
'https://graph.facebook.com/me?fields=email
the i get the following reponse as
{"error":{"message":"An active access token must be used to query information about the current user.","type":"OAuthException","code":2500}}

Answer 1

Probably you do not have adequate permission to access that data. The code you provided doesn't indicate if you have requested email permission on authorization process so I'm guessing you didn't request it.
When you redirect your user to Auth Dialog, which is like https://www.facebook.com/dialog/oauth/?client_id=YOUR_APP_ID&redirect_uri=YOUR_REDIRECT_URL&state=YOUR_STATE_VALUE&scope=COMMA_SEPARATED_LIST_OF_PERMISSION_NAMES , you have to specify scope=email to acquire permission to access email field.
To check if you have the permission, you can access the URL below and see if you have it.
my $permission_ref = $fb->get(
'https://graph.facebook.com/me/permissions'
);
The returning value should be something like below.
{
"data": [
{
"installed": 1,
"email": 1
}
]
}
If it includes email, you have the permission to access user email.
If not you'll have to request permission to get it. With Net::Facebook::OAuth2, you can generate this dialog url like below.
my $fb = Net::Facebook::Oauth2->new(
application_id => 'your_application_id',
application_secret => 'your_application_secret',
callback => 'http://yourdomain.com/facebook/callback'
);
my $url = $fb->get_authorization_url(
scope => ['email'],
);
Redirect your user to this url and you'll get the permission.
And even if you have email permission, sometimes email is not returned because of a bug. You might want to check this bug report, "API call to /me is missing user's email even with email permission."