复选框表单验证 [英] Checkbox form validation

问题描述

如何验证Flutter Form 中的复选框?其他所有验证都可以正常工作，但是该复选框没有显示错误.这是我的代码:

How can I validate a checkbox in a Flutter Form? Every other validation works fine, but the checkbox doesn't show an Error. Here is my code:

FormField(
  validator: (value) {
    if (value == false) {
      return 'Required.';
    }
  },
  builder: (FormFieldState<dynamic> field) {
    return CheckboxListTile(
      value: checkboxValue,
      onChanged: (val) {
        if (checkboxValue == false) {
          setState(() {
            checkboxValue = true;
          });
        } else if (checkboxValue == true) {
          setState(() {
            checkboxValue = false;
          });
        }
      },
      title: new Text(
        'I agree.',
        style: TextStyle(fontSize: 14.0),
      ),
      controlAffinity: ListTileControlAffinity.leading,
      activeColor: Colors.green,
    );
  },
),

推荐答案

对此问题的一种更清洁的解决方案是，创建一个扩展 FormField< bool>

A cleaner solution to this problem is to make a class that extends FormField<bool>

这是我的完成方式:

class CheckboxFormField extends FormField<bool> {
  CheckboxFormField(
      {Widget title,
      FormFieldSetter<bool> onSaved,
      FormFieldValidator<bool> validator,
      bool initialValue = false,
      bool autovalidate = false})
      : super(
            onSaved: onSaved,
            validator: validator,
            initialValue: initialValue,
            builder: (FormFieldState<bool> state) {
              return CheckboxListTile(
                dense: state.hasError,
                title: title,
                value: state.value,
                onChanged: state.didChange,
                subtitle: state.hasError
                    ? Builder(
                        builder: (BuildContext context) =>  Text(
                          state.errorText,
                          style: TextStyle(color: Theme.of(context).errorColor),
                        ),
                      )
                    : null,
                controlAffinity: ListTileControlAffinity.leading,
              );
            });
}

这篇关于复选框表单验证的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！