如何在react中使用上下文提供程序内部的axios get调用

Question

我想调用以获取用户信息，并在整个应用程序的不同组件中使用它，所以我使用react。Context和我设法在组件之间移动了一个字符串，但当我尝试使用axios.get时，我无法将数据获取到另一个组件，下面是上下文代码：

import React, { createContext } from 'react';
import axios from 'axios';
export const userContext = createContext();
export const UserProvider = (props) => {
const config = {
headers: {
'Content-Type': 'application/json',
'Authorization': `JWT ${localStorage.getItem('access')}`,
'Accept': 'application/json'
}
};
const res = axios.get(`${process.env.REACT_APP_API_URL}/auth/users/me/`, config)
return(
<userContext.Provider value= { res }>{props.children}</userContext.Provider>
);
} 

有人能告诉我我在这里做错了什么吗

Answer 1

如果您可以轻松处理state，它将更易于管理。而不是将res(我认为它将是您的状态(直接传递给Provider。我认为，随着时间的推移，如果您有多个state要添加到User上下文中。你也需要通过他们作为value。这是不灵活的。

我建议你这样管理它们：-

1. 拥有专用的User上下文文件夹：src/contexts/User

• src/contexts/User/UserContext(创建User上下文(

import { createContext } from "react";
export const UserContext = createContext();

• src/contexts/User/UserReducer(处理state更新(

export default (state, action) => {
switch (action.type) {
case "SET_USER":
return {
...state,
user: action.payload
};
case "SET_ERROR":
return {
...state,
error: action.payload.error,
message: action.payload.message
};
case "SET_LOADING":
return {
...state,
loading: action.payload
};
default:
return state;
}
};

• src/contexts/User/UserAction(处理对state所做的action。基本上是对state进行更改所需的任何操作(

import axios from "axios";
// Set Loading
export const setLoading = (dispatch, status) =>
dispatch({ type: "SET_LOADING", payload: status });
// Set Error
export const setError = (dispatch, error) =>
dispatch({
type: "SET_ERROR",
payload: { error: error.status, message: error.message }
});
// Set User (get user info)
export const getUser = async dispatch => {
setLoading(dispatch, true);
// do fetch
await axios
.get(`https://jsonplaceholder.typicode.com/users/1`)
.then(res => {
const result = res.data;
// set user info
dispatch({
type: "SET_USER",
payload: result
});
})
.catch(error => {
const result = error;
// set error if has any
dispatch({
type: "SET_ERROR",
payload: {
error: true,
message: result
}
});
});
};

• src/contexts/User/UserState(处理state初始化。如果您有，您可以稍后在下面的const initialState中添加更多或初始化更多状态。此外，您不需要在未来添加更多value。(

import React, { useContext, useReducer } from "react";
import { UserContext } from "./UserContext";
import UserReducer from "./UserReducer";
export const useUser = () => {
const { state, dispatch } = useContext(UserContext);
return [state, dispatch];
};
export const UserState = ({ children }) => {
const initialState = {
user: {},
loading: false,
error: false,
message: ""
};
const [state, dispatch] = useReducer(UserReducer, initialState);
return (
<UserContext.Provider
value={{
state: state,
dispatch: dispatch
}}
>
{children}
</UserContext.Provider>
);
};

然后你可以这样使用它们：-

1. 确保要使用User上下文的encapsulate的任何component(这将在App.js中(

• App.js：-

import React from "react";
import { UserState } from "./contexts/User/UserState";
import Demo from "./Demo";
import "./style.css";
export default function App() {
return (
<UserState>
<Demo />
</UserState>
);
}

2. 您可以使用useState在UserState中使用任何stateinitialized：-

• Demo.js(App.js子组件(：-

import React, { useEffect } from "react";
import { useUser } from "./contexts/User/UserState";
import { getUser, setLoading } from "./contexts/User/UserAction";
import "./style.css";
const Demo = () => { 
const [userState, userDispatch] = useUser();
const { user, loading, error, message } = userState;
// get user info handler
const getUserInfoHandler = async () => {
await getUser(userDispatch);
setLoading(userDispatch, false);
};
// get user info
useEffect(() => {
getUserInfoHandler();
}, []);
return (
<div>
{loading && <p>Loading...</p>}
{error && <p>{message}</p>}
<p>User name: {user.name}</p>
</div>
);
};
export default Demo;

你可以在沙箱中看到工作代码