The error message is: type 'Null' is not a subtype of type 'String'-CodePudding

The error displays a null value for the email parameter.

  class RegisterEmailPage extends HookWidget {

  @override
  Widget build(BuildContext context) {
    final formState = useState(GlobalKey<FormBuilderState>());

    return Scaffold(
      floatingActionButton: FloatingActionButton(
        onPressed: () {

          bool? validated = formState.value.currentState?.validate();

          if (validated == true) {
            print('Now I\'m here &&&&& formState.value.currentState?.value is: ' formState.value.currentState?.value['email'] );
            String email = formState.value.currentState?.value['email'];
            print('email is : ....'   formState.value.currentState?.value['email']);
            Provider.of<AuthProvider>(context, listen: false)
                .registerCheckEmail(context, email: email, onSuccess: (res) {});
          } else {
          }
        },

Even though I set a few prints for get Log, I did not get any log in order to check the value of this parameter.

CodePudding user response：

You are getting null from response formState.value.currentState?.value['email']. Please check the value you are getting from above code.

CodePudding user response：

Try this:

String email = formState.value.currentState?.value['email']??"Email Not Found";

Whenever you get null email it will take "No Email Found" value. So you do not get Null Value error.

CodePudding user response：

Since flutter2, null safety which has been mandatory and we have to handle nulls when we are not sure if the response is non-null. And there is always a possibility that

formState.value.currentState

can be null.

Hence you have two ways to handle this,

you can either change your variable type to

String? email = formState.value.currentState?.value['email'];
or with the existing variable type you can use,

email = formState.value.currentState?.value['email'] ?? "";

This should help.