Flutter-The parameter 'email' can't have a value of 'null' because of its type, but the implicit default value is 'null'

Question

I'm new to flutter and I'm working on http post request by creating a model.

class LoginResponseModel {
  final String token;
  final String error;

  LoginResponseModel({this.token, this.error});

  factory LoginResponseModel.fromJson(Map<String, dynamic> json) {
    return LoginResponseModel(
      token: json["token"] != null ? json["token"] : "",
      error: json["error"] != null ? json["error"] : "",
    );
  }
}

class LoginRequestModel {
  String email;
  String password;
  String tenant;

  LoginRequestModel({
    this.email,
    this.password,
    this.tenant,
  });

  Map<String, dynamic> toJson() {
    Map<String, dynamic> map = {
      'email': email.trim(),
      'password': password.trim(),
      'token':tenant.trim(),
    };

    return map;
  }
}

I am getting error in the following parts of this code :

LoginRequestModel({
    this.email,
    this.password,
    this.tenant,
  });

The parameter 'email' can't have a value of 'null' because of its type, but the implicit default value is 'null'

Then I follow the path below when using this model I created to log in via the login page.

LoginRequestModel requestModel;
@override
void initState() {
super.initState();
requestModel = LoginRequestModel(email: '', password: '', tenant: ''); //After adding required, I have to enter these fields.

and when i send login request via button i see this in debug console.

{email: , password: , token: }

Answer 1

For a named parameter, if you don't indicate that it's required, then it could be null.

Change it to:

LoginRequestModel({
    required this.email,
    required this.password,
    required this.tenant,
  });