React Hook useEffect 缺少依賴項：'fetchData'

Question

誰能幫我解決這個錯誤？ 在useEffect 中，我調用了一個發出請求並將響應插入到 redux 狀態的函數。

import React, { useEffect, useState } from "react";
import { BrowserRouter as Router, Switch, Route} from "react-router-dom";
import { useDispatch, useSelector } from 'react-redux'
import { actions } from './actions/actions'
import { I18nProvider } from './i18n'
import axios from 'axios'

import Home from './views/home/home';
import Page1 from './views/page1/page1';
import Page2 from './views/page2/page2'
import Page3 from './views/page3/page3'

const App = () => {

  const [isLoading, setIsLoading] = useState(true)

  const localeDefault = useSelector(state => state.audioGuideReducers.lang)

  const dispatch = useDispatch()
  const setDataRedux= (data) => dispatch(actions.setDataRedux(data))

  useEffect(() => {
    fetchData();
  }, []);

  const fetchData = async () => {
    await axios.get('https://link-api.com/alldata')
      .then((response) => {
        setDataRedux(response.data.data)
        setIsLoading(false)
      })
      .catch( (error) => {
        console.log(error.message);
      })
  }

  return (
    <I18nProvider locale={localeDefault}>
      <Router>
        {
          isLoading ?
            <h1> Loading... </h1>
            :
            <Switch>
              <Route path="/page3/:id" component={Page3} />
              <Route path="/page2" component={Page2} />
              <Route path="/page1" component={Page1} />
              <Route path="/" component={Home} />
            </Switch>
        }
      </Router>
    </I18nProvider>
  );
}

export default App

盡管應用程序正在“運行”，但我想解決出現的以下警告：“ React Hook useEffect 缺少依賴項：'fetchData'。包括它或刪除依賴項矩陣 react-hooks/exaustive-deps ”

Answer 1

將fetchData作為參數傳遞給useEffect

 useEffect(() => {
    fetchData();
  }, [fetchData]);

Answer 2

這是因為每當您使用useEffect以及使用useEffect之外的東西時。 UseEffect 需要確保何時更新，這就是為什么您需要在其依賴項中傳遞它：

useEffect(() => {
    fetchData();
  }, [fetchData]);

  const fetchData = async () => {
    await axios.get('https://link-api.com/alldata')
      .then((response) => {
        setDataRedux(response.data.data)
        setIsLoading(false)
      })
      .catch( (error) => {
        console.log(error.message);
      })
  }

如果你只需要在useEffect里面把fetchData放在fetchData里面， useEffect更好的方法是：

const setDataRedux = React.useCallback((data) => dispatch(actions.setDataRedux(data)), [])
useEffect(() => {
    const fetchData = async () => {
    await axios.get('https://link-api.com/alldata')
      .then((response) => {
        setDataRedux(response.data.data)
        setIsLoading(false)
      })
      .catch( (error) => {
        console.log(error.message);
      })
  }
    fetchData();
  }, [setDataRedux]);