[英]React/Redux - dispatch action on app load/init
我有來自服務器的令牌身份驗證,因此當我的 Redux 應用程序最初加載時,我需要向該服務器發出請求以檢查用戶是否已通過身份驗證,如果是,我應該獲取令牌。
我發現不推薦使用 Redux 核心 INIT 操作,那么在呈現應用程序之前如何調度操作?
您可以在 Root componentDidMount
方法中調度操作,在render
方法中您可以驗證身份驗證狀態。
像這樣的東西:
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)
我對為此提出的任何解決方案都不滿意,然后我想到我正在考慮需要呈現的類。 如果我剛剛創建了一個用於啟動的類,然后將內容推送到componentDidMount
方法中,並且只讓render
顯示一個加載屏幕呢?
<Provider store={store}>
<Startup>
<Router>
<Switch>
<Route exact path='/' component={Homepage} />
</Switch>
</Router>
</Startup>
</Provider>
然后有這樣的事情:
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);
然后編寫一些 redux 操作來異步初始化您的應用程序。 很好用。
這里的所有答案似乎都是創建根組件並在 componentDidMount 中觸發它的變體。 我最喜歡 redux 的一件事是它將數據從組件生命周期中提取出來。 在這種情況下,我看不出有什么不同的理由。
如果你將你的商店導入到根index.js
文件中,你可以在那個文件中調度你的動作創建者(我們稱之為initScript()
),它會在加載任何東西之前觸發。
例如:
//index.js
store.dispatch(initScript());
ReactDOM.render(
<Provider store={store}>
<Routes />
</Provider>,
document.getElementById('root')
);
如果您使用的是 React Hooks,一種單行解決方案是
useEffect(() => store.dispatch(handleAppInit()), []);
空數組確保它只在第一次渲染時被調用一次。
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>
);
}
2020 年更新:與其他解決方案一起,我使用 Redux 中間件來檢查每個請求是否有失敗的登錄嘗試:
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:此答案適用於React Router 3
我使用 react-router onEnter道具解決了這個問題。 這是代碼的樣子:
// 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>
);
使用redux-saga中間件你可以做得很好。
只需定義一個 saga,它在被觸發之前不會監視已調度的動作(例如,使用take
或takeLatest
)。 當像這樣從 root saga fork
ed 時,它將在應用程序啟動時只運行一次。
以下是一個不完整的例子,它需要一些關於redux-saga
包的知識,但說明了這一點:
傳奇/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];
上述調度代碼launchStart
和launchComplete
Redux的動作,你應該創建。 創建這樣的操作是一個很好的做法,因為它們可以派上用場,以便在啟動或完成時通知狀態執行其他操作。
你的 root saga 應該分叉這個launchSaga
saga:
傳奇/ 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;
請閱讀redux-saga非常好的文檔以獲取更多信息。
這是使用 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>);
}
相似,但是是上述的替代方法(這僅適用於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);
};
我正在使用 redux-thunk 從應用程序初始化的 API 端點獲取用戶下的帳戶,並且它是異步的,因此數據在我的應用程序呈現后進入,並且上面的大多數解決方案對我來說並沒有產生奇跡,有些是貶值。 所以我查看了 componentDidUpdate()。 所以基本上在 APP init 上,我必須有來自 API 的帳戶列表,而我的 redux 商店帳戶將為空或 []。 之后就這樣了。
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);
如果你使用 React Hooks,你可以簡單地使用 React.useEffect 調度一個動作
React.useEffect(props.dispatchOnAuthListener, []);
我使用此模式注冊onAuthStateChanged
偵聽器
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);
與上面提到的 Chris Kemp 相同的解決方案。 可能更通用,只是一個與 redux 無關的 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;
使用:Apollo Client 2.0、React-Router v4、React 16 (Fiber)
選擇的答案使用舊的 React Router v3。 我需要執行“調度”來加載應用程序的全局設置。 訣竅是使用 componentWillUpdate,雖然示例使用的是 apollo 客戶端,但不獲取解決方案是等效的。 你不需要滾球
設置加載.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;
應用程序.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"
/>
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