Flutter数据可视化与UI组件插件dash_kit_core的使用

Dash Kit Core 是一个提供基本架构组件的库，它基于Async Redux包构建，并提供了额外的API，例如用于监视应用程序中操作当前状态的操作状态API和高效的存储和更新数据的StoreList。

什么是AsyncRedux？

async_redux 的工作流如下图所示：

其主要概念区别在于引入了异步Reducer（Async Reducer），允许声明返回Future的异步操作。更多关于async_redux的信息，可以参考这篇文章或直接访问官方文档。

示例代码

class QueryAndIncrementAction extends ReduxAction<AppState> {
  @override
  Future<AppState> reduce() async {
    int value = await getAmount();
    return state.copy(counter: state.counter + value);
  }
}

操作 Operations

在开发过程中，我们经常需要执行许多异步操作并在它们完成后做某些事情。因此，Dash Kit Core添加了获取异步操作状态的功能。通过为ReduxAction添加一个包装器来实现这一点，该包装器称为Action。为了确保类型安全，我们可以编写另一个包装器，定义特定的操作类型。

枚举操作类型

enum Operation {
  login,
  loginViaFacebook,
  loginViaGoogle,
  loginViaApple,
}

创建应用状态

import 'package:built_value/built_value.dart';

part 'app_state.g.dart';

abstract class AppState implements Built<AppState, AppStateBuilder>, GlobalState {
  factory AppState([void Function(AppStateBuilder) updates]) = _$AppState;

  AppState._();

  ProfileState get profile;

  @override
  BuiltMap<Object, OperationState> get operationsState;

  @override
  T updateOperation<T extends GlobalState>(
     Object? operationKey,
     OperationState operationState,
  ) {
    if (operationKey == null) {
      return this as T;
    }

    final GlobalState newState = rebuild(
      (s) => s.operationsState[operationKey] = operationState,
    );
    return newState as T;
  }

  @override
  OperationState getOperationState(Object operationKey) {
    return operationsState[operationKey] ?? OperationState.idle;
  }

  static AppState initial() {
    return AppState(
      (b) => b.profile = ProfileState.initial().toBuilder(),
    );
  }
}

登录操作示例

class LoginAction extends Action<AppState> {
  LoginAction({
    required this.email,
    required this.password,
  });

  final String email;
  final String password;

  @override
  Operation get operationKey => Operation.login;

  @override
  Future<AppState> reduce() async {
    final currentUserName = await Future.delayed(Duration(seconds: 5), () {
      if (email.isNotEmpty && password.isNotEmpty) {
        return 'UserName';
      }
    });

    return state.rebuild((s) {
      s.profileState.name = currentUserName;
    });
  }
}

在UI中使用操作状态

class _MyHomePageState extends State<MyHomePage> {
  final _formKey = GlobalKey<FormState>();
  final _emailController = TextEditingController();
  final _passwordController = TextEditingController();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: StoreConnector<AppState, OperationState>(
        converter: (store) => store.state.getOperationState(Operation.login),
        builder: (context, operationState) => LoadableView(
          isLoading: operationState.isInProgress,
          child: Padding(
            padding: const EdgeInsets.all(8),
            child: Form(
              key: _formKey,
              child: Column(
                children: [
                  TextFormField(
                    controller: _emailController,
                    decoration: const InputDecoration(hintText: 'Email'),
                  ),
                  TextFormField(
                    controller: _passwordController,
                    decoration: const InputDecoration(hintText: 'Password'),
                    obscureText: true,
                  ),
                  TextButton(
                    onPressed: _onLoginPressed,
                    child: const Text('LOG IN'),
                  ),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }

  Future<void> _onLoginPressed() async {
    return context
        .dispatchAndWait(
          LoginAction(
            email: _emailController.text,
            password: _passwordController.text,
          ),
        )
        .then((_) => _openSuccessDialog())
        .catchError(_onError);
  }

  void _onError(dynamic error) {
    showDialog(
        context: context,
        builder: (context) {
          return Dialog(
            shape: RoundedRectangleBorder(
              borderRadius: BorderRadius.circular(6),
            ),
            backgroundColor: Colors.white,
            child: const SizedBox(
              height: 100,
              width: 100,
              child: Center(
                child: Text('ERROR: something went wrong'),
              ),
            ),
          );
        });
  }

  void _openSuccessDialog() {
    final state = StoreProvider.state<AppState>(context);
    final userName = state.profileState.name;

    showDialog(
        context: context,
        builder: (context) {
          return Dialog(
            shape: RoundedRectangleBorder(
              borderRadius: BorderRadius.circular(6),
            ),
            backgroundColor: Colors.white,
            child: SizedBox(
              height: 100,
              width: 100,
              child: Center(
                child: Text('Hi, $userName!'),
              ),
            ),
          );
        });
  }
}

StoreList

StoreList是对BuiltList的一个封装，提供了更方便的方式来更新存储中的数据。它适用于存储列表或字典类型的数据。

示例代码

// 定义用户资料类
class UserProfile implements StoreListItem {
  UserProfile({Object id}) : super(id);
}

// 在全局状态中使用StoreList
StoreList<UserProfile> get userProfiles;

// 获取所有项
state.userProfiles.itemsMap;

// 获取所有ID
state.userProfiles.itemsIds;

// 获取单个项
state.userProfiles.getItem('Some ID according to type which you use');

// 删除项
@override
Future<AppState> reduce() async {
  return state.dataStructure.someOldList.deleteItem(conditionItemId);
}

PaginatedList

PaginatedList用于分页加载数据，通常包含以下元信息：

• items: 数据项
• meta: 分页信息（如前一页、当前页、下一页、总条数）

初始化和更新

// 初始化
static AppState initial() {
  return AppState(
    (b) => b.paginatedList = PaginatedList<YourType>.empty(),
  );
}

// 更新
@Override
Future<AppState> reduce() async {
  return state.paginatedList.update(
    items: newItems,
    totalCount: response.totalCount,
  );
}

通过以上内容，您应该能够理解如何使用dash_kit_core进行数据可视化和UI组件的集成。希望这些信息对您有所帮助！