我想在useEffect react Js中使用带有foreach的axios，但它给了我（无法读取属性Symbol（Symbol.iterator）错误？

Posted 2023-03-17

【中文标题】我想在useEffect react Js中使用带有foreach的axios，但它给了我（无法读取属性Symbol（Symbol.iterator）错误？

【英文标题】：I want to use axios with foreach in useEffect react Js but it gives me (cannot read property Symbol(Symbol.iterator) error?

【发布时间】：2021-09-08 23:36:17

【问题描述】：

我想在 foreach 中调用 axios，但它给了我错误“未处理的拒绝 (TypeError): undefined is not iterable (cannot read property Symbol(Symbol.iterator))”

let BooksInfo=["Atomic Habit","Feel the Fear . . . and Do It Anyway","The Four Agreements"]

export default BooksInfo;

这是我的第一次尝试：

import './App.css';
import Card from "./Card"
import Books from "./Books"
import  useEffect  from 'react';
import axios from "axios"
import  promised  from 'q';
function App() 
  useEffect( ()=>
    
    async function test()
      

        await Promise.all(Books.forEach( (book)=>
        console.log(book + "????????????")
        const test1= axios.get(`https://openlibrary.org/search.json?q=$book`)
        console.log(test1)
      ))
    
    test()
    console.log("outside")
  )

我也尝试过这种方式，但它仍然给我同样的错误

import './App.css';
import Card from "./Card"
import Books from "./Books"
import  useEffect  from 'react';
import axios from "axios"
import  promised  from 'q';
function App() 
  useEffect( ()=>
    
    async function test()
      

      const test1= await Promise.all(Books.forEach( (book)=>
        console.log(book + "????????????")
        axios.get(`https://openlibrary.org/search.json?q=$book`)
        .then(res=>
          console.log("helooo")
          console.log(res)
          // console.log(tes)
        )
      ))
    
    test()
    console.log("outside")
  ) 

【参考方案1】：

我会建议一种更好的方法，这样您就可以在进行 API 调用时轻松捕获错误。

  try 
    const result = await Promise.all(BooksInfo.map( (book)=>
      console.log(book + "???")
      const test1= axios.get(`https://openlibrary.org/search.json?q=$book`)
      return test1; // This is essential; this is how map func works
    ))

    console.info("API Result", result);
   catch (error) 
    console.error("Network error",error);
  

【参考方案2】：

我认为问题可能出在Books。 您在将其导出为BooksInfo 并将其导入为Books 时对其进行迭代，如果导入不正确，则书籍为null，因此会触发错误