sum<U extends num> method Null safety

Future<U?> sum<U extends num>(
  1. U? selector(
    1. T object

Finds the sum of some ManagedObject property.

selector identifies the property being evaluated, e.g.

    var query = new Query<User>();
    var yearsLivesByAllUsers = await query.reduce.sum((user) => user.age);

The property must be an attribute and its type must be an num, i.e. int or double.


Future<U?> sum<U extends num>(U? selector(T object));