React useEffect hook 和 Async/await 自己的获取数据功能? [英] React useEffect hook and Async/await own fetch data func?

问题描述

我尝试创建一个从服务器获取数据的函数，它工作正常.但我不确定这是否正确?

I tried to create a function for fetching data from the server, and it works. But I am not sure if that the right way?

我使用useState、useEffect 和Async/Await 创建了一个函数组件来获取数据:

I created a function component to fetching data, using useState, useEffect and Async/Await :

import React, { useState, useEffect } from "react";

const Fetch = () => {
  const [data, setData] = useState(null);
  useEffect(() => {
    const fetchData = async () => {
      let res = await fetch(
        "https://api.coindesk.com/v1/bpi/currentprice.json" //example and simple data
      );
      let response = await res.json();
      setData(response.disclaimer); // parse json
      console.log(response);
    };
    fetchData();
  }, []);
  return <div>{data}</div>;
};

export default Fetch; // don't run code snippet, not working, this component must be imported in main

我不确定的地方是何处调用fetchData 函数.我在useEffect里面做那个?正确的位置?并且，这个调用只会发生一次?因为我使用 []?

Where I am not sure is a place where to call the fetchData function. I do that inside useEffect? Right place? And, this call will happen only one? Because i use []?

一般来说，你会怎么做这样的事情?

Generally, how would you do something like this?

推荐答案

总的来说，您正朝着正确的方向前进.为了获取数据，您需要使用 useEffect 并将 [] 作为第二个参数传递，以确保它仅在初始安装时触发.

Overall, you are heading in the right direction. For fetching data, you'd wanna use useEffect and pass [] as a second argument to make sure it fires only on initial mount.

我相信您可以从分离 fetchJson 函数并使其更通用中受益，例如:

I believe you could benefit from decoupling fetchJson function and making it more generic, as such:

const fetchJson = async (url) => {
  const response = await fetch(url);
  return response.json();
};

const Fetch = () => {
  const [data, setData] = useState(null);

  useEffect(() => {
    fetchJson("https://api.coindesk.com/v1/bpi/currentprice.json")
      .then(({ disclaimer }) => setData(disclaimer));
  }, []);

  return <div>{data}</div>;
};

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