I use widget StatefulWidget and _inputFiled

I've created a model class

class Profile {
  String? email;
  String? username;
  String? password;

  Profile({
    this.email,
    this.username,
    this.password,
  });
}

And using like

class _RegisterScreenState extends State<RegisterScreen> {
  final formKey = GlobalKey<FormState>();
  Profile profile = Profile();

  @override
  Widget build(BuildContext context) {
    return Form(
      child: Scaffold(
        body: Container(
          margin: EdgeInsets.all(24),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.spaceEvenly,
            children: [
             // _header(context),
              _inputField(context),
             // _forgotPassword(context),
            ],
          ),
        ),
      ),
    );
  }
 _inputField(context) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.stretch,
      children: [
        TextFormField(
          keyboardType: TextInputType.emailAddress,
          onSaved: (String? email) {
            formKey.currentState?.save();
            profile.email = email!;
          },
        ),
        SizedBox(height: 10),
        TextFormField(
          onSaved: (String? username) {
            formKey.currentState?.save();
            profile.username = username!;
          },
        ),
        SizedBox(height: 10),
        TextFormField(
          onSaved: (String? password) {
            profile.password = password!;
          },
        ),
        SizedBox(height: 10),
        ElevatedButton(
          onPressed: () {
            formKey.currentState?.save(); // Save the entire form
            print(
                "email =${profile.email} username =${profile.username} password =${profile.password}");
            Navigator.push(context, MaterialPageRoute(builder: ((context) {
              return LoginScreen();
            })));
          },
          child: Text(
            "Register",
          ), 
        )
      ],
    );
  }

Terminal say : email =null username =null password =null

CodePudding user response：

The form key hasn't been used.

  Widget build(BuildContext context) {
    return Form(
      key: formKey, // add here
      child: Scaffold(

CodePudding user response：

You need put your Global key in your form:

  return Form(
      key: formKey,
      child: Scaffold(
 

And the formKey.currentState?.save() only on

 ElevatedButton(
          onPressed: () {
            formKey.currentState?.save(); // Save the entire form
            print(
                "email =${profile.email} username =${profile.username} password =${profile.password}");

it is not needed in onSave methods as it will be executed first on button onPressed

CodePudding user response：

It is becauae you made them null able and if you dont initialize them the first value will be null.