Flutter表单验证插件easy_breezy_validator的使用

当然，下面是一个关于如何在Flutter中使用easy_breezy_validator插件进行表单验证的代码示例。这个插件可以帮助你简化表单验证的过程。

首先，你需要在你的pubspec.yaml文件中添加easy_breezy_validator依赖：

dependencies:
  flutter:
    sdk: flutter
  easy_breezy_validator: ^x.y.z  # 请替换为最新版本号

然后运行flutter pub get来获取依赖。

接下来，我们可以创建一个简单的表单，并使用easy_breezy_validator进行验证。

1. 创建数据模型

首先，我们需要定义一个数据模型，并使用@required和@validate注解来指定哪些字段是必填的，以及如何验证这些字段。

import 'package:easy_breezy_validator/easy_breezy_validator.dart';

class UserModel {
  @required
  @validate(minLength: 3, maxLength: 15, message: "Name must be between 3 and 15 characters")
  String name = "";

  @required
  @validate(email: true, message: "Please enter a valid email address")
  String email = "";

  @required
  @validate(minLength: 6, message: "Password must be at least 6 characters long")
  String password = "";

  // Convert to a map for easy JSON serialization/deserialization
  Map<String, dynamic> toMap() {
    return {
      'name': name,
      'email': email,
      'password': password,
    };
  }
}

2. 创建表单UI

然后，我们创建一个简单的表单UI来收集用户输入。

import 'package:flutter/material.dart';
import 'package:easy_breezy_validator/easy_breezy_validator.dart';
import 'user_model.dart';  // 假设你将上面的模型保存在 user_model.dart 文件中

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Form Validation Example'),
        ),
        body: Padding(
          padding: const EdgeInsets.all(16.0),
          child: MyForm(),
        ),
      ),
    );
  }
}

class MyForm extends StatefulWidget {
  @override
  _MyFormState createState() => _MyFormState();
}

class _MyFormState extends State<MyForm> {
  final _formKey = GlobalKey<FormState>();
  late UserModel user;
  late EasyBreezyValidator validator;

  @override
  void initState() {
    super.initState();
    user = UserModel();
    validator = EasyBreezyValidator(user);
  }

  void _submitForm() {
    if (_formKey.currentState!.validate()) {
      if (validator.validate()) {
        // If validation passes, you can submit the form
        print('Form Submitted');
        print(user.toMap());
      } else {
        // If validation fails, print the errors
        validator.errors.forEach((key, value) {
          print("${key.toString().split('.').last}: ${value.join(', ')}");
        });
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Form(
      key: _formKey,
      child: Column(
        children: [
          TextFormField(
            decoration: InputDecoration(labelText: 'Name'),
            validator: (value) {
              if (value == null || value.isEmpty) {
                return 'Name is required';
              }
              // Since we're already validating with EasyBreezyValidator, we don't need to re-validate here
              return null;
            },
            onSaved: (value) {
              user.name = value!;
            },
          ),
          TextFormField(
            decoration: InputDecoration(labelText: 'Email'),
            validator: (value) {
              if (value == null || value.isEmpty) {
                return 'Email is required';
              }
              // Since we're already validating with EasyBreezyValidator, we don't need to re-validate here
              return null;
            },
            onSaved: (value) {
              user.email = value!;
            },
          ),
          TextFormField(
            decoration: InputDecoration(labelText: 'Password'),
            validator: (value) {
              if (value == null || value.isEmpty) {
                return 'Password is required';
              }
              // Since we're already validating with EasyBreezyValidator, we don't need to re-validate here
              return null;
            },
            obscureText: true,
            onSaved: (value) {
              user.password = value!;
            },
          ),
          ElevatedButton(
            onPressed: _submitForm,
            child: Text('Submit'),
          ),
        ],
      ),
    );
  }
}

3. 运行应用

将上述代码保存并运行你的Flutter应用。现在，你应该能够看到一个包含姓名、电子邮件和密码字段的表单。当你尝试提交表单时，easy_breezy_validator将自动验证这些字段，并在验证失败时显示相应的错误消息。

请注意，由于easy_breezy_validator已经处理了大部分验证逻辑，因此在TextFormField的validator回调中，我们只需要检查字段是否为空（如果需要的话）。实际的验证逻辑是在validator.validate()方法中完成的。