在React JS中使用路由器时如何使用Context API传递状态 [英] How to use Context API to pass down a state while using a Router in React JS

问题描述

我有一个Context API文件设置，该文件具有一个状态和一个从API提取数据并设置状态的函数，我想将该状态传递给其他组件.在我的App.js中，我正在使用React-Router来指定路由.在使用React-Router的同时，如何使用Context API将状态传递给这些组件.

I have a Context API file setup which has a state and a function which fetches data from an API and sets the state, and i want to pass the state down to my other components. In my App.js, I am using React-Router to specify the routes. How do i pass the state down to these components using Context API, whilst using React-Router.

我的ApiContext.js文件如下所示:

My ApiContext.js file looks like this :

import React, {useState, createContext } from 'react';

export const ApiContext = createContext();

export const ApiProvider = async (props) => {
    const [data, setData] = useState(null);

    const getURL = 'https://examplefetchsite.com';
    const response = await fetch(getURL).json();
    setData(response);
    return (
        <ApiContext.Provider value={[data, setData]}>
            {props.children}
        </ApiContext.Provider>
    );
}

我的App.js的返回看起来像这样:

My App.js's return looks like this :

return (
      <ApiProvider>
        <Router>
          <div>
            <NavBar />
            <Switch>
            <Route path="/" exact component={ Dashboard } />
            <Route path="/create" component={ Create } />
            <Route path="/view" component={View} />
            </Switch>
          </div>
        </Router>
      </ApiProvider>
    )

推荐答案

就上下文本身而言，您不必更改提供程序中的任何内容，而只需在子组件中执行以下操作:

In terms of the context itself, you don't have to change anything in your provider and only do something like this in the child components:

import React, {useContext} from 'react'
import {ApiContext} from './ApiContext'

const Dashboard = (props) => {
    const [data, setData] = useContext(ApiContext)

    //you should have access to both data and setData

    return (
        //things
    )
}

但是，在 ApiContext.js 中，您没有正确调用API请求.您应该使用 useEffect 仅在第一个渲染器上获取数据.

However in the ApiContext.js you aren't calling the API request properly. You should use useEffect to fetch the data only on the first render.

import React, {useState, createContext, useEffect} from 'react';

export const ApiContext = createContext();

export const ApiProvider = (props) => {
    const [data, setData] = useState(null);

    useEffect(async () => {
        const getURL = 'https://examplefetchsite.com';
        const response = await fetch(getURL).json();
        setData(response);
    }, [])

    return (
        <ApiContext.Provider value={[data, setData]}>
            {props.children}
        </ApiContext.Provider>
    );
}

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