NoSuchMethodError: The method '[]' was called on null. (Flutter)

Question

I am running my Flutter app and getting this error:

The method '[]' was called on null.
Receiver: null
Tried calling: []("id")

This is My User Class:-

class User {

final String id;
final String username;
final String email;
final String photoUrl;


User({
  this.id,
  this.username,
  this.email,
  this.photoUrl,
});

 factory User.fromDocument(DocumentSnapshot doc) {
   return User(
    id: doc.data()['id'],
    username: doc.data()['username'],
    email: doc.data()['email'],
    photoUrl: doc.data()['photoUrl'],

    );
  }
}

The Document in the database isn't null, What Could Be Causing This Problem ??

Answer 1

Try this one

 factory User.fromDocument(DocumentSnapshot doc) {
   if(doc.data() == null){
      return User();
   }
   return User(
    id: doc.data()['id'],
    username: doc.data()['username'],
    email: doc.data()['email'],
    photoUrl: doc.data()['photoUrl'],
    );
  }