创建Firebase注册函数时遇错误：Instance member 'user'无法静态访问

问题详情 #

开发注册功能时，执行String userId = UserCredential.user!.uid;代码时触发错误提示：Instance member 'user' can't be accessed using static access.

原代码如下：

final auth = FirebaseAuth.instance;
final db = FirebaseFirestore.instance;
Future<bool> register(String email, String password, String username) async {
  try {
    await FirebaseAuth.instance
        .createUserWithEmailAndPassword(email: email, password: password);

    
   String userId = UserCredential.user!.uid;
   final userRef = FirebaseFirestore.instance.collection('users').doc(userId);
    await userRef.set({
      'username': username,
      'email': email,
    });
    return true;
  } on FirebaseAuthException catch (e) {
    if (e.code == 'weak-password') {
      print('Password provided is too weak');
      global.error = "Password provided is too weak";
    } else if (e.code == 'email-already-in-use') {
      global.error = "The account already exist for that email.";
      print('The account already exist for that email.');
    }
    return false;
  } catch (e) {
    print(e.toString());
    return false;
  }
}

解决方案 #

错误核心是：user是UserCredential的实例属性，不能直接通过类名静态访问，必须先获取createUserWithEmailAndPassword返回的实例对象，再通过实例访问user。

修改后的代码：

final auth = FirebaseAuth.instance;
final db = FirebaseFirestore.instance;
Future<bool> register(String email, String password, String username) async {
  try {
    // 接收createUserWithEmailAndPassword返回的UserCredential实例
    UserCredential userCredential = await FirebaseAuth.instance
        .createUserWithEmailAndPassword(email: email, password: password);

    // 通过实例对象访问user属性
    String userId = userCredential.user!.uid;
    final userRef = FirebaseFirestore.instance.collection('users').doc(userId);
    await userRef.set({
      'username': username,
      'email': email,
    });
    return true;
  } on FirebaseAuthException catch (e) {
    if (e.code == 'weak-password') {
      print('Password provided is too weak');
      global.error = "Password provided is too weak";
    } else if (e.code == 'email-already-in-use') {
      global.error = "The account already exist for that email.";
      print('The account already exist for that email.');
    }
    return false;
  } catch (e) {
    print(e.toString());
    return false;
  }
}

关键修改点 #

• 新增UserCredential userCredential = await ...，接收注册接口返回的实例对象
• 将UserCredential.user!.uid改为userCredential.user!.uid，通过实例访问属性

内容的提问来源于stack exchange，提问作者Chinmay