为什么 state 没有以肘为单位更新？

Question

I am new at flutter ant trying to use bloc/cubit

I have a state inside cubit file and when I try to emit state... state is not changing and I don't understand why

This is my cubit file:

//auth_cubit.dart

import 'package:flutter_bloc/flutter_bloc.dart';

part of 'auth_state.dart'; // here ide returns an error: The part-of directive must be the only directive in a part.

class AuthCubit extends Cubit<AuthState> { // The name 'AuthState' isn't a type so it can't be used as a type argument.
  AuthCubit() : super(AuthState(
    email: "Log in",
    password: null,
    firstName: "",
    lastName: "",
    genderId: 0,
    ageGroupId: 0,
    countryUuid: 0
  ));

  void setCountryUuid(int countryUuid) => emit(AuthState(countryUuid: countryUuid));

}

//auth_state.dart

part of 'auth_cubit.dart';

class AuthState {
  final email;
  final password;
  final firstName;
  final lastName;
  final genderId;
  final ageGroupId;
  final countryUuid;

  const AuthState({
    this.email, //string
    this.password, //string
    this.firstName, //string
    this.lastName, //string
    this.genderId, //int
    this.ageGroupId, //int
    this.countryUuid //int
  });
}

Why does state cannot connect to cubit?

Answer 1

There is error to fix first, see above on the part part (ahah):

import 'package:flutter_bloc/flutter_bloc.dart';

part 'auth_state.dart'; // Just use part in the cubit

class AuthCubit extends Cubit<AuthState> { // This error should be gone
  AuthCubit() : super(AuthState(
    email: "Log in",
    password: null,
    firstName: "",
    lastName: "",
    genderId: 0,
    ageGroupId: 0,
    countryUuid: 0
  ));

  void setCountryUuid(int countryUuid) => emit(AuthState(countryUuid: countryUuid));

}

After that, your cubit should be able to emit new state.

Answer 2

Using equatable will help for value equality.

By default, == returns true if two objects are the same instance.

class AuthState extends Equatable {
  final String? email;
  final String? password;
  final String? firstName;
  final String? lastName;
  final int? genderId;
  final int? ageGroupId;
  final int? countryUuid;

  const AuthState({
    this.email,
    this.password,
    this.firstName,
    this.lastName,
    this.genderId,
    this.ageGroupId,
    this.countryUuid,
  });

  AuthState copyWith({
    String? email,
    String? password,
    String? firstName,
    String? lastName,
    int? genderId,
    int? ageGroupId,
    int? countryUuid,
  }) {
    return AuthState(
      email: email ?? this.email,
      password: password ?? this.password,
      firstName: firstName ?? this.firstName,
      lastName: lastName ?? this.lastName,
      genderId: genderId ?? this.genderId,
      ageGroupId: ageGroupId ?? this.ageGroupId,
      countryUuid: countryUuid ?? this.countryUuid,
    );
  }

  @override
  List<Object?> get props =>
      [email, password, firstName, lastName, genderId, ageGroupId, countryUuid];
}

emit new instance to update the UI.

emit(state.copyWith(countryUuid: countryUuid));