How to reset error message in TextFormField?

Question

I know this is a simple question but i did not find how to do this. How can i reset error message in TextFormField when the user input something in the field. Something like onchange listener. I notice onChanged is available in TextField but not TextFormField. How can i do this?

final _email = Container(
  child: TextFormField(
    decoration: InputDecoration(labelText: email),
    keyboardType: TextInputType.emailAddress,
    controller: emailController,
    validator: _validateEmail,
    onSaved: (input) => _stringEmail = input.toLowerCase().trim(),
  ),
);

UPDATE: I am using controller to add listener for user input. But i just want to reset the error message instead of validating the form again. Is this possible? How can i do this?

  _resetEmailErrorMessage() {
    print("Second text field: ${emailController.text}");
    //replace clear to something that can reset the validation error message
    emailController.clear();
  }

  @override
  void initState() {
    super.initState();

    //start listening to changes
    emailController.addListener(_resetEmailErrorMessage);
  }

Answer 1

You can use auto-validation feature of Form

If you looking for this solution,

"As soon as you type it validates your input and show/hide error"

Flutter provides auto-validation feature, you just need to enable it at form level.

1. Default

   _autoValidate = false;

2. Form

    body: Form( key: _formKey,
                autovalidate: _autoValidate,....)

3. Enable it when user presses submit once,

    if (_formKey.currentState.validate()) {
      // All Good
    } else {
      // start auto validate
      setState(() {
        _autoValidate = true;
      });
    }

Update :-

Now Form.autovalidate is deprecated. So Use

Form.autovalidateMode = AutovalidateMode.onUserInteraction