如何通过 Stream<string> 值作为在块文件 FLUTTER 中创建的 function 的参数</string>

Question

I have a login bloc file where I have created 2 streams username and password

class LoginBloc {
  LoginRepository _loginRepository = new LoginRepository();
  StreamController _loginController = StreamController<Response<LoginModel>>();

  //declare streams
  final _userName = BehaviorSubject<String>();
  final _password = BehaviorSubject<String>();

  //get data from streams
  StreamSink<Response<LoginModel>> get loginControllerSink =>
  _loginController.sink;
  Stream<String> get loginUserName => _userName.stream;
  Stream<String> get loginPassword => _password.stream;
  Stream<bool> get submitLoginForm =>
      Rx.combineLatest2(loginUserName, loginPassword, (a, b) => true);

  Function(String) get changeLoginUserName => _userName.sink.add;
  Function(String) get changeLoginPassword => _password.sink.add;

  //dispose
  dispose() {
    _userName.close();
    _password.close();
  }

  //functions
  login(email, password, context) async {
    try {
      LoginModel data = await _loginRepository.loginIntoSystem(email, password);
      loginControllerSink.add(Response.completed(data));    
      Navigator.pushNamed(context, '/dashboard');
    } catch (e) {
      loginControllerSink.add(Response.error(e.toString()));
      print(e);
    }
  }
}

Here's the login.dart

    class Login extends StatefulWidget {
  @override
  _LoginState createState() => _LoginState();
}

class _LoginState extends State<Login> {
  bool _passwordVisible = false;
  @override
  Widget build(BuildContext context) {
    Size size = MediaQuery.of(context).size;
    final LoginBloc bloc = LoginProvider.of(context);
    return Scaffold(
      backgroundColor: Colors.white,
      body: SingleChildScrollView(
        child: SafeArea(
          child: Center(
            child:
            Column(
              children: <Widget>[
                SizedBox(height: size.height*0.05),
                Icon(
                  Icons.track_changes,
                  size: size.width*0.06,
                ),
                SizedBox(height: size.height*0.02),
                Text('Login',
                    style: TextStyle(
                        color: Color(0xff005D6C),
                        fontSize: size.width*0.02,
                        fontWeight: FontWeight.bold,
                        fontStyle: FontStyle.italic)),
                SizedBox(height: size.height*0.04),
                Container(
                  width: size.width * 0.2,
                  padding: EdgeInsets.only(bottom: 20.0),
                  child: StreamBuilder<String>(
                      stream: bloc.loginUserName,
                      builder: (context, snapshot) {
                        return TextField(
                          onChanged: bloc.changeLoginUserName,
                          decoration: new InputDecoration(
                              contentPadding: EdgeInsets.symmetric(vertical: 0, horizontal: 15.0),
                              border: new OutlineInputBorder(
                                  borderSide: const BorderSide(
                                      width: 2.0, style: BorderStyle.solid),
                                  borderRadius: BorderRadius.circular(50.0)),
                              focusedBorder: OutlineInputBorder(
                                borderSide: const BorderSide(
                                    color: Colors.grey, width: 2.0),
                                borderRadius: BorderRadius.circular(50.0),
                              ),
                              hintText: 'User Name',
                              hintStyle: new TextStyle(
                                  color: Colors.grey,
                                  fontWeight: FontWeight.bold),
                              suffixIcon: const Icon(
                                Icons.person,
                                size: 30.0,
                                color: Colors.grey,
                              ),
                              errorText: snapshot.error),
                        );
                      }),
                ),
                Container(
                  width: size.width * 0.2,
                  padding: EdgeInsets.only(bottom: 20.0),
                  child: StreamBuilder<String>(
                      stream: bloc.loginPassword,
                      builder: (context, snapshot) {
                        return TextField(
                          onChanged: bloc.changeLoginPassword,
                          obscureText: !_passwordVisible,
                          maxLength: 20,
                          decoration: new InputDecoration(
                              contentPadding: EdgeInsets.symmetric(vertical: 0, horizontal: 15.0),
                              border: new OutlineInputBorder(
                                  borderSide: const BorderSide(
                                      width: 2.0, style: BorderStyle.solid),
                                  borderRadius: BorderRadius.circular(50.0)),
                              focusedBorder: OutlineInputBorder(
                                borderSide: const BorderSide(
                                    color: Colors.grey, width: 2.0),
                                borderRadius: BorderRadius.circular(50.0),
                              ),
                              hintText: 'Password',
                              hintStyle: new TextStyle(
                                  color: Colors.grey,
                                  fontWeight: FontWeight.bold),
                              prefixIcon: const Icon(
                                Icons.lock,
                                size: 30.0,
                                color: Colors.grey,
                              ),
                              suffixIcon: IconButton(
                                icon: Icon(
                                  // Based on passwordVisible state choose the icon
                                  _passwordVisible
                                      ? Icons.visibility
                                      : Icons.visibility_off,
                                  color: Colors.grey,
                                ),
                                onPressed: () {
                                  setState(() {
                                    _passwordVisible = !_passwordVisible;
                                  });
                                },
                              ),
                              errorText: snapshot.error),
                        );
                      }),
                ),

                Container(
                  width: size.width * 0.2,
                  child: ClipRRect(
                    borderRadius: BorderRadius.circular(29),
                    child: StreamBuilder<bool>(
                      stream: bloc.submitLoginForm,
                      builder: (context, snapshot){
                        return FlatButton(
                          color: Color(0XFFEFEFEF),
                          textColor: primaryColor,
                          disabledColor: Colors.grey,
                          disabledTextColor: Colors.black,
                          padding: EdgeInsets.symmetric(
                              vertical: 12.0, horizontal: 10.0),
                          onPressed: () => snapshot.hasError ? null : bloc.login(bloc.loginUserName, bloc.loginPassword, context) ,
                          child: Text(
                            "Login",
                            style: TextStyle(
                                fontSize: 20.0,
                                fontWeight: FontWeight.bold,
                                fontStyle: FontStyle.italic),
                          ),
                        );
                      },
                    ),
                  ),
                )
              ],
            )
          ),
        ),
      ),
    );
  }
}

I am calling the login function on CLick of login button and passing the username, password and context as parameters. But on click its giving "Expected a value of type 'String', but got one of type 'BehaviorSubject'"

added the loginIntoSystem:

Future<LoginModel> loginIntoSystem(String email, String password) 
async {
    dynamic body = {
      'email': email,
      'password': password
    };
    final response = await _provider.post("/login", body);
    return LoginModel.fromJson(response);
  }

Is there a way to convert BehaviorSubject to String?

Answer 1

I found the solution.

By using value property, I was able to get the values.

    final fEmail = _email.value;
    final fPassword =  _password.value;

Thank you everyone for taking your time and posting the answers.

Answer 2

You are right. I was wrong, and behavior subject has a property value which returns value of that behavior subject. You can use this to get the email and password out of your behavior subject. Also, since your bloc file already has access to those variables, you don't have to pass them as arguments from your onPressed function.

login(context) async {
    final email = _userName.value;
    final password = _password.value;
    try {
      LoginModel data = await _loginRepository.loginIntoSystem(email, password);
      loginControllerSink.add(Response.completed(data));    
      Navigator.pushNamed(context, '/dashboard');
    } catch (e) {
      loginControllerSink.add(Response.error(e.toString()));
      print(e);
    }
  }