如何在 React 的 Context 提供程序中使用 axios get 调用

Question

我想拨打电话来获取用户信息并在整个应用程序的不同组件中使用它，所以我使用了react.Context，并且我设法在组件之间移动字符串，但是当我尝试使用 axios.get 时，我是无法将数据获取到另一个组件，这里是上下文代码：

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>
    );
} 

有人可以告诉我我在这里做错了什么吗

Answer 1

state如果你能以无忧无虑的方式处理，那就更容易管理。而不是将res我认为将是您的状态的 直接传递给Provider. 我认为，如果你有多个state想要添加到你的User上下文中的话。你也需要将它们传递为value. 那将不灵活。

我建议你像这样管理它们：-

1. 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actiondid state。基本上是您需要对 进行更改的任何内容state）

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。如果有的话，您可以稍后在下面添加更多或初始化更多状态。另外，您将来const initialState也不需要添加更多。）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>
  );
};

然后你可以像这样使用它们：-

1. 确保您想要使用encapsulate上下文（这将位于）componentUserApp.js

• 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. 您可以通过state initialized以下方式使用任何：-UserStateuseState

• 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;

您可能会在沙箱中看到工作代码