Cannot access copyWith method on freezed class

Question

I have a freezed class and somehow I cannot access copyWith method. What is my mistake?

Class:

@freezed
class LoginState with _$LoginState {

  const factory LoginState({
    String? username,
    String? password,
    @Default(false) bool isValid,
    String? errorMessage,
  }) = _LoginState;

  factory LoginState.empty() => LoginState();
  factory LoginState.initial() = _Initial;
}

Try to access copyWith like this:

LoginState state = LoginState();
state.copyWith(); //cannot access copyWith

Answer 1

copyWith is only generated for classes that have parameters in their constructors. In your case, _LoginState is the only one with parameters: so:

LoginState state1 = _LoginState();
state1.copyWith(); //works!

LoginState state2 = _Initial();
state2.copyWith(); //Doesn't exist on this class

(state3 as _LoginState).copyWith(); //works!

So either do this type casting to make sure you're working with a class that has parameters, or add a parameter to _Initial to give it a copyWith method that actually does something.