React/Redux - 在应用加载/初始化时分派动作

Question

我有来自服务器的令牌身份验证，因此当我的 Redux 应用程序最初加载时，我需要向该服务器发出请求以检查用户是否已通过身份验证，如果是，我应该获取令牌。

我发现不推荐使用 Redux 核心 INIT 操作，那么在呈现应用程序之前如何调度操作？

Answer 1

您可以在 Root componentDidMount方法中调度操作，在render方法中您可以验证身份验证状态。

像这样的东西：

class App extends Component {
  componentDidMount() {
    this.props.getAuth()
  }

  render() {
    return this.props.isReady
      ? <div> ready </div>
      : <div>not ready</div>
  }
}

const mapStateToProps = (state) => ({
  isReady: state.isReady,
})

const mapDispatchToProps = {
  getAuth,
}

export default connect(mapStateToProps, mapDispatchToProps)(App)

Answer 2

我对为此提出的任何解决方案都不满意，然后我想到我正在考虑需要呈现的类。 如果我刚刚创建了一个用于启动的类，然后将内容推送到componentDidMount方法中，并且只让render显示一个加载屏幕呢？

<Provider store={store}>
  <Startup>
    <Router>
      <Switch>
        <Route exact path='/' component={Homepage} />
      </Switch>
    </Router>
  </Startup>
</Provider>

然后有这样的事情：

class Startup extends Component {
  static propTypes = {
    connection: PropTypes.object
  }
  componentDidMount() {
    this.props.actions.initialiseConnection();
  }
  render() {
    return this.props.connection
      ? this.props.children
      : (<p>Loading...</p>);
  }
}

function mapStateToProps(state) {
  return {
    connection: state.connection
  };
}

function mapDispatchToProps(dispatch) {
  return {
    actions: bindActionCreators(Actions, dispatch)
  };
}

export default connect(
  mapStateToProps,
  mapDispatchToProps
)(Startup);

然后编写一些 redux 操作来异步初始化您的应用程序。 很好用。

Answer 3

这里的所有答案似乎都是创建根组件并在 componentDidMount 中触发它的变体。 我最喜欢 redux 的一件事是它将数据从组件生命周期中提取出来。 在这种情况下，我看不出有什么不同的理由。

如果你将你的商店导入到根index.js文件中，你可以在那个文件中调度你的动作创建者（我们称之为initScript() ），它会在加载任何东西之前触发。

例如：

//index.js

store.dispatch(initScript());

ReactDOM.render(
  <Provider store={store}>
    <Routes />
  </Provider>,
  document.getElementById('root')
);

Answer 4

如果您使用的是 React Hooks，一种单行解决方案是

useEffect(() => store.dispatch(handleAppInit()), []);

空数组确保它只在第一次渲染时被调用一次。

完整示例：

import React, { useEffect } from 'react';
import { Provider } from 'react-redux';

import AppInitActions from './store/actions/appInit';
import store from './store';

export default function App() {
  useEffect(() => store.dispatch(AppInitActions.handleAppInit()), []);
  return (
    <Provider store={store}>
      <div>
        Hello World
      </div>
    </Provider>
  );
}

Answer 5

2020 年更新：与其他解决方案一起，我使用 Redux 中间件来检查每个请求是否有失败的登录尝试：

export default () => next => action => {
  const result = next(action);
  const { type, payload } = result;

  if (type.endsWith('Failure')) {
    if (payload.status === 401) {
      removeToken();

      window.location.replace('/login');
    }
  }

  return result;
};

2018 年更新：此答案适用于React Router 3

我使用 react-router onEnter道具解决了这个问题。 这是代码的样子：

// this function is called only once, before application initially starts to render react-route and any of its related DOM elements
// it can be used to add init config settings to the application
function onAppInit(dispatch) {
  return (nextState, replace, callback) => {
    dispatch(performTokenRequest())
      .then(() => {
        // callback is like a "next" function, app initialization is stopped until it is called.
        callback();
      });
  };
}

const App = () => (
  <Provider store={store}>
    <IntlProvider locale={language} messages={messages}>
      <div>
        <Router history={history}>
          <Route path="/" component={MainLayout} onEnter={onAppInit(store.dispatch)}>
            <IndexRoute component={HomePage} />
            <Route path="about" component={AboutPage} />
          </Route>
        </Router>
      </div>
    </IntlProvider>
  </Provider>
);

Answer 6

使用redux-saga中间件你可以做得很好。

只需定义一个 saga，它在被触发之前不会监视已调度的动作（例如，使用take或takeLatest ）。 当像这样从 root saga fork ed 时，它将在应用程序启动时只运行一次。

以下是一个不完整的例子，它需要一些关于redux-saga包的知识，但说明了这一点：

传奇/launchSaga.js

import { call, put } from 'redux-saga/effects';

import { launchStart, launchComplete } from '../actions/launch';
import { authenticationSuccess } from '../actions/authentication';
import { getAuthData } from '../utils/authentication';
// ... imports of other actions/functions etc..

/**
 * Place for initial configurations to run once when the app starts.
 */
const launchSaga = function* launchSaga() {
  yield put(launchStart());

  // Your authentication handling can go here.
  const authData = yield call(getAuthData, { params: ... });
  // ... some more authentication logic
  yield put(authenticationSuccess(authData));  // dispatch an action to notify the redux store of your authentication result

  yield put(launchComplete());
};

export default [launchSaga];

上述调度代码launchStart和launchComplete Redux的动作，你应该创建。 创建这样的操作是一个很好的做法，因为它们可以派上用场，以便在启动或完成时通知状态执行其他操作。

你的 root saga 应该分叉这个launchSaga saga：

传奇/ index.js

import { fork, all } from 'redux-saga/effects';
import launchSaga from './launchSaga';
// ... other saga imports

// Single entry point to start all sagas at once
const root = function* rootSaga() {
  yield all([
    fork( ... )
    // ... other sagas
    fork(launchSaga)
  ]);
};

export default root;

请阅读redux-saga非常好的文档以获取更多信息。

Answer 7

这是使用 React (16.8) 中最新的 Hooks 的答案：

import { appPreInit } from '../store/actions';
// app preInit is an action: const appPreInit = () => ({ type: APP_PRE_INIT })
import { useDispatch } from 'react-redux';
export default App() {
    const dispatch = useDispatch();
    // only change the dispatch effect when dispatch has changed, which should be never
    useEffect(() => dispatch(appPreInit()), [ dispatch ]);
    return (<div>---your app here---</div>);
}

Answer 8

相似，但是是上述的替代方法（这仅适用于React-Router v3）：

Routes.js

import React from 'react';
import { Route, IndexRoute } from 'react-router';

import App from '../components/App';
import Home from '../views/Home';
import OnLoadAuth from '../containers/app/OnLoadAuth';

export default = (
  <Route path="/" component={OnLoadAuth(App)}>
    <IndexRoute component={Home} />
    {* Routes that require authentication *}
  </Route>
);

OnLoadAuth.js

import React, { Component } from 'react';
import { connect } from 'react-redux';

import { authenticateUser, fetchingUser } from '../../actions/AuthActionCreators';
import Spinner from '../../components/loaders/Spinner';

export default App => {
  class OnLoadAuth extends Component {
    componentDidMount = () => this.props.authenticateUser();

    render = () => (
      (this.props.isLoading === undefined || this.props.isLoading)
       ? <Spinner />
       : <App {...this.props} />
    )
 }

 return connect(
    state => ({ isLoading: state.auth.fetchingUser }),
      { authenticateUser, fetchingUser }
    )(OnLoadAuth);
};

Answer 9

我正在使用 redux-thunk 从应用程序初始化的 API 端点获取用户下的帐户，并且它是异步的，因此数据在我的应用程序呈现后进入，并且上面的大多数解决方案对我来说并没有产生奇迹，有些是贬值。 所以我查看了 componentDidUpdate()。 所以基本上在 APP init 上，我必须有来自 API 的帐户列表，而我的 redux 商店帐户将为空或 []。 之后就这样了。

class SwitchAccount extends Component {

    constructor(props) {
        super(props);

        this.Format_Account_List = this.Format_Account_List.bind(this); //function to format list for html form drop down

        //Local state
        this.state = {
                formattedUserAccounts : [],  //Accounts list with html formatting for drop down
                selectedUserAccount: [] //selected account by user

        }

    }



    //Check if accounts has been updated by redux thunk and update state
    componentDidUpdate(prevProps) {

        if (prevProps.accounts !== this.props.accounts) {
            this.Format_Account_List(this.props.accounts);
        }
     }


     //take the JSON data and work with it :-)   
     Format_Account_List(json_data){

        let a_users_list = []; //create user array
        for(let i = 0; i < json_data.length; i++) {

            let data = JSON.parse(json_data[i]);
            let s_username = <option key={i} value={data.s_username}>{data.s_username}</option>;
            a_users_list.push(s_username); //object
        }

        this.setState({formattedUserAccounts: a_users_list}); //state for drop down list (html formatted)

    }

     changeAccount() {

         //do some account change checks here
      }

      render() {


        return (
             <Form >
                <Form.Group >
                    <Form.Control onChange={e => this.setState( {selectedUserAccount : e.target.value})} as="select">
                        {this.state.formattedUserAccounts}
                    </Form.Control>
                </Form.Group>
                <Button variant="info" size="lg" onClick={this.changeAccount} block>Select</Button>
            </Form>
          );


         }    
 }

 const mapStateToProps = state => ({
      accounts: state.accountSelection.accounts, //accounts from redux store
 });


  export default connect(mapStateToProps)(SwitchAccount);

Answer 10

如果你使用 React Hooks，你可以简单地使用 React.useEffect 调度一个动作

React.useEffect(props.dispatchOnAuthListener, []);

我使用此模式注册onAuthStateChanged侦听器

function App(props) {
  const [user, setUser] = React.useState(props.authUser);
  React.useEffect(() => setUser(props.authUser), [props.authUser]);
  React.useEffect(props.dispatchOnAuthListener, []);
  return <>{user.loading ? "Loading.." :"Hello! User"}<>;
}

const mapStateToProps = (state) => {
  return {
    authUser: state.authentication,
  };
};

const mapDispatchToProps = (dispatch) => {
  return {
    dispatchOnAuthListener: () => dispatch(registerOnAuthListener()),
  };
};

export default connect(mapStateToProps, mapDispatchToProps)(App);

Answer 11

与上面提到的 Chris Kemp 相同的解决方案。 可能更通用，只是一个与 redux 无关的 canLift func？

interface Props {
  selector: (state: RootState) => boolean;
  loader?: JSX.Element;
}

const ReduxGate: React.FC<Props> = (props) => {
  const canLiftGate = useAppSelector(props.selector);
  return canLiftGate ? <>{props.children}</> : props.loader || <Loading />;
};

export default ReduxGate;

Answer 12

使用：Apollo Client 2.0、React-Router v4、React 16 (Fiber)

选择的答案使用旧的 React Router v3。 我需要执行“调度”来加载应用程序的全局设置。 诀窍是使用 componentWillUpdate，虽然示例使用的是 apollo 客户端，但不获取解决方案是等效的。 你不需要滚球

设置加载.js

import React, { Component } from 'react';
import { connect } from 'react-redux';
import {bindActionCreators} from "redux";
import {
  graphql,
  compose,
} from 'react-apollo';

import {appSettingsLoad} from './actions/appActions';
import defQls from './defQls';
import {resolvePathObj} from "./utils/helper";
class SettingsLoad extends Component {

  constructor(props) {
    super(props);
  }

  componentWillMount() { // this give infinite loop or no sense if componente will mount or not, because render is called a lot of times

  }

  //componentWillReceiveProps(newProps) { // this give infinite loop
  componentWillUpdate(newProps) {

    const newrecord = resolvePathObj(newProps, 'getOrgSettings.getOrgSettings.record');
    const oldrecord = resolvePathObj(this.props, 'getOrgSettings.getOrgSettings.record');
    if (newrecord === oldrecord) {
      // when oldrecord (undefined) !== newrecord (string), means ql is loaded, and this will happens
      //  one time, rest of time:
      //     oldrecord (undefined) == newrecord (undefined)  // nothing loaded
      //     oldrecord (string) == newrecord (string)   // ql loaded and present in props
      return false;
    }
    if (typeof newrecord ==='undefined') {
      return false;
    }
    // here will executed one time
    setTimeout(() => {
      this.props.appSettingsLoad( JSON.parse(this.props.getOrgSettings.getOrgSettings.record));
    }, 1000);

  }
  componentDidMount() {
    //console.log('did mount this props', this.props);

  }

  render() {
    const record = resolvePathObj(this.props, 'getOrgSettings.getOrgSettings.record');
    return record
      ? this.props.children
      : (<p>...</p>);
  }
}

const withGraphql = compose(

  graphql(defQls.loadTable, {
    name: 'loadTable',
    options: props => {
      const optionsValues = {  };
      optionsValues.fetchPolicy = 'network-only';
      return optionsValues ;
    },
  }),
)(SettingsLoad);


const mapStateToProps = (state, ownProps) => {
  return {
    myState: state,
  };
};

const mapDispatchToProps = (dispatch) => {
  return bindActionCreators ({appSettingsLoad, dispatch }, dispatch );  // to set this.props.dispatch
};

const ComponentFull = connect(
  mapStateToProps ,
  mapDispatchToProps,
)(withGraphql);

export default ComponentFull;

应用程序.js

class App extends Component<Props> {
  render() {

    return (
        <ApolloProvider client={client}>
          <Provider store={store} >
            <SettingsLoad>
              <BrowserRouter>
            <Switch>
              <LayoutContainer
                t={t}
                i18n={i18n}
                path="/myaccount"
                component={MyAccount}
                title="form.myAccount"
              />
              <LayoutContainer
                t={t}
                i18n={i18n}
                path="/dashboard"
                component={Dashboard}
                title="menu.dashboard"
              />