Store 没有 reducer initialState

Question

我无法获取 store reducer initialState，因此我也无法映射到组件中的 props。

这是我的减速器：

const initialState = { currentUser: null }

export default function UserReducer(state = initialState, action){
   let nextState;
   switch(action.type){
    case "USER_CONNECTED":
        nextState = {
            ...state,
            currentUser : action.value
        }
        return nextState;
    case "USER_DECONNECTED":
        nextState = {
            ...state,
            currentUser : null
        }
        return nextState;
    default:
        return state;
  }
}

这里是配置商店的class：

import { createStore, combineReducers } from 'redux';
import UserReducer from './reducers/userReducer'

const rootReducer = combineReducers({
    currentUser : UserReducer
});

const configureStore = () => {
    return createStore(rootReducer);
}

export default configureStore;

这里是我初始化商店并将其传递给应用程序的地方，感谢提供商：

import {AppRegistry} from 'react-native';
import React from 'react';
import App from './App';
import {name as appName} from './app.json';
import { Provider } from 'react-redux';
import configureStore from './store/store';


const Store = configureStore();
console.log("STORE :"+ JSON.stringify(Store.getState()));
const RNRedux = () => (

    <Provider store = { Store }>
      <App />
    </Provider>
)

AppRegistry.registerComponent(appName, () => RNRedux);

当我打印上面的 "STORE" 时，它给了我正确的输出 { currentUser : ...}。然后我按如下方式将 App.js 连接到商店：

const AppNavigator = createStackNavigator(
{
    NewAccount: NewAccountScreen,
    Login: LoginScreen
},
{
    initialRouteName: "Login"
}
);

const AppContainer = createAppContainer(AppNavigator);

export class App extends React.Component {

    constructor(props, context){
      super(props, context);
    }

    render() {
      console.log("APP.JS : "+ JSON.stringify(this.props));
      return (
        <AppContainer />
      )
    }
  }

  export default connect()(App);

所以在最后一行，我将整个 App 状态连接到组件道具，但它给了我 {}.

Answer 1

您在连接调用中缺少 mapStateToProps 参数。

export default connect()(App);

您需要指定将获取部分状态并将其传递给组件属性的映射函数。要将整个状态映射到道具，试试这个：

export default connect(state=>state)(App)

更好的做法是只传递组件需要的部分状态。这样，当状态的其他部分发生变化时，您就可以避免不必要的重新渲染。例如，如果您的连接组件只需要用户名，您可以这样做：

export default connect(state=>{firstName:state.currentUser.firstName})(App)

Store 没有 reducer initialState

Store does not have reducer initialState

state

store

react-native

redux