未处理抛出错误！无法解构'(0 , react_redux__WEBPACK_IMPORTED_MODULE_2__.useSelector)(...)'的属性"类别"，因为它未定义

Question

Auth.js

import { createSlice } from "@reduxjs/toolkit";
export const authSlice = createSlice({
name: "auth",
initialState: {
isAuthenticated: false,
user: {},
},
reducers: {
setUser: (state, { payload }) => {
state.user = payload.user;
state.isAuthenticated = true;
},
logout: (state) => {
state.user = {};
state.isAuthenticated = false;
},
},
});
export const { setUser, logout } = authSlice.actions;
export default authSlice.reducer;

index.js(商店)

import { configureStore } from "@reduxjs/toolkit";
import authReducer from "./auth.js";
export default configureStore({
reducer: {
auth: authReducer,
},
});

交易表单.js

const { categories } = useSelector((state) => state.auth.user);

**当我登录时出现了一个错误，但在重新加载页面时，错误就消失了。如何修复错误**

Answer 1

如果你没有登录，你就不会得到一个用户，然后你就无法从中提取类别

const { categories } = useSelector((state) => state.auth.user ?? {categories: []});

根据你对用户和类别数据的处理方式，你最好这样做：

const user = useSelector((state) => state.auth.user);
if(!user){
return;
}
const categories = user.categories
...