Question

NextJS：TypeError：无法读取未定义的属性“json”

2020-09-09

3526

javascript json reactjs next.js

我已将此代码放入 NextJS 环境的 pages 文件夹中。它通过调用外部 API Rest 获取数据，并且它正在运行，因为 console.log(response); 行通过控制台向我显示了 Json API 响应。我遇到的问题是，我在浏览器中收到此错误：

TypeError：无法读取未定义的属性“json”

与此行代码相对应：

const data = await res.json();

这是包含代码的完整文件：

import React from "react";
import fetch from "node-fetch";

const getFetch = async (invoicesUrl, params) => {
  fetch(invoicesUrl, params)
    .then((response) => {
      return response.json();
    })
    .then((response) => {
      console.log(response);
    })
    .catch((err) => {
      console.log(err);
    });
};

export const getServerSideProps = async () => {
  const invoicesUrl = "https://192.168.1.38/accounts/123456";
  const params = {
    method: "get",
    headers: {
      Accept: "application/json",
      "Content-Type": "application/json",
    },
  };
  const res = await getFetch(invoicesUrl, params);
  const data = await res.json();
  console.log("Data Json: ", data);

  return { props: { data } };
};

这是我在控制台上看到的 Json API 响应：

{
  account: [
    {
      id: '7051321',
      type: 'probe',
      status: 'open',
      newAccount: [Object],
      lastDate: '2020-07-04',
      taxExcluded: [Object],
      totalRecover: [Object],
      documentLinks: []
    },
  ]
}

有什么想法可以解决它吗？提前致谢。

更新以下代码运行良好：

import React from "react";
import fetch from "node-fetch";

const getFetch = async (invoicesUrl, params) => {
   return fetch(invoicesUrl, params);
};

export const getServerSideProps = async () => {
  const invoicesUrl = "https://192.168.1.38/accounts/123456";
  const params = {
    method: "get",
    headers: {
      Accept: "application/json",
      "Content-Type": "application/json",
    },
  };
  try {
    const res = await getFetch(invoicesUrl, params);
    const data = await res.json();
    console.log("Data JSON: ", data);
    return { props: { data } };
  } catch (error) {
    console.log("Data ERROR: ", error);
  }
};

Answer 1

有几件事你需要改变。

const getFetch = async (invoicesUrl, params) => {
  fetch(invoicesUrl, params)
    .then((response) => {
      return response.json();
    })
    .then((response) => {
      console.log(response);
      return response; // 1. Add this line. You need to return the response.
    })
    .catch((err) => {
      console.log(err);
    });
};

export const getServerSideProps = async () => {
  const invoicesUrl = "https://192.168.1.38/accounts/123456";
  const params = {
    method: "get",
    headers: {
      Accept: "application/json",
      "Content-Type": "application/json",
    },
  };
  const data = await getFetch(invoicesUrl, params);
  // const data = await res.json(); 2. Remove this you have already converted to JSON by calling .json in getFetch
  console.log("Data Json: ", data); // Make sure this prints the data.

  return { props: { data } };
};

Answer 2

您的 return 语句放错了位置。当函数期望返回时。您需要在执行语句时返回，而不是在承诺 then 函数内，因为它是一个异步回调函数，与 getFetch 函数内的语句不同步。我希望我已经说清楚了。以下是无论如何都会返回某些内容的代码

import React from "react";
import fetch from "node-fetch";

const getFetch = async (invoicesUrl, params) => {
  return fetch(invoicesUrl, params);
};

export const getServerSideProps = async () => {
  const invoicesUrl = "https://192.168.1.38/accounts/123456";
  const params = {
    method: "get",
    headers: {
      Accept: "application/json",
      "Content-Type": "application/json",
    },
  };
  try{
     const res = await getFetch(invoicesUrl, params);
     console.log("Data Json: ", res);
  }catch(error){
     console.log("Data Json: ", error);
  }
  return { props: { res } };
};