NextJS：TypeError：无法读取未定义的属性“json”

Question

我已将此代码放入 NextJS 环境中的 pages 文件夹中。它获取调用外部 API Rest 的数据，并且它正在工作，因为 console.log(response); 行通过控制台向我显示 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”

对应这行代码：

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 } };
};

这是我通过控制台看到的 Json API 响应：

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

知道如何解决吗？ 提前致谢。

更新 这里的代码运行良好：

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

有几件事你必须改变。

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 语句在错误的位置。 当函数期望返回时。当语句不在 Promise then 函数内执行时，您需要返回，因为它是一个异步回调函数，与 getFetchfunction 内的语句不同步。我希望我已经把事情说清楚了。以下是返回内容的代码

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 } };
};