Reactjs 从存储中存储和检索状态
我正在尝试将Reactjs 从存储中存储和检索状态,reactjs,redux,react-redux,react-hooks,Reactjs,Redux,React Redux,React Hooks,我正在尝试将userToken保存在Redux存储中并检索它。在我的index.js中,我用Provider包装我的App,它将store作为道具: import { createStore } from "redux"; import { Provider } from "react-redux"; import rootReducer from "./reducers/rootReducer"; const store = createStore(rootReducer); ReactD
userToken
保存在Redux存储中并检索它。在我的index.js
中,我用Provider
包装我的App
,它将store
作为道具:
import { createStore } from "redux";
import { Provider } from "react-redux";
import rootReducer from "./reducers/rootReducer";
const store = createStore(rootReducer);
ReactDOM.render(
<Provider store={store}>
<App />
</Provider>,
document.getElementById("root")
);
我已经定义了一个助手函数validateLogInTest
:
export const validateLoginAttempt = payload => {
if (typeof payload.data.token !== "undefined") {
//Saves in localstorage correctly.
localStorage.setItem("userToken", payload.data.token);
return true;
}
return false;
};
在我的一个功能组件中,我有一个fetch()
const dispatch = useDispatch();
<...>
.then(data => {
dispatch({ type: "login", payload: { data } });
history.push("/");
})
这给了我一个错误
:
Error: An error occured while selecting the store state: Cannot read property 'userToken' of undefined.
如果我尝试在我的App
组件中按如下方式getStore
,我会得到storeundefined
:
const store = useStore();
console.log("store", store.getState());
有人能帮我找到正确的方向吗?我无法解决这个问题。有多个问题,但最大的问题是:
reducer是一个纯函数,它接受前一个状态和一个动作,返回下一个状态
您不从reducer返回任何内容(隐式地返回undefined
),因此导致TypeError无法读取undefined的属性“userToken”。
:
const initialState = {};
const rootReducer = (state = initialState, action) => {
switch (action.type) {
case "login": {
return {...state, userToken: action.payload.data.token};
}
default:
return state;
}
};
而“纯函数”意味着没有副作用,因此localStorage.setItem
内部validateLogInTest
在减速机中没有位置,应该放在action creator中:
const dispatch = useDispatch();
...
.then(data => {
const isLoggedIn = validateLoginAttempt(data);
if (isLoggedIn) {
dispatch({ type: "login", payload: { data } });
history.push("/");
} else {
console.error("not logged in")
}
})
非常感谢。除了返回{…状态之外,userToken:action.payload.data.token}代码>。从存储中删除相同的userToken
的正确方法是什么?类似于case'logout':返回{…state,userToken:null}
const initialState = {};
const rootReducer = (state = initialState, action) => {
switch (action.type) {
case "login": {
return {...state, userToken: action.payload.data.token};
}
default:
return state;
}
};
const dispatch = useDispatch();
...
.then(data => {
const isLoggedIn = validateLoginAttempt(data);
if (isLoggedIn) {
dispatch({ type: "login", payload: { data } });
history.push("/");
} else {
console.error("not logged in")
}
})