Axios POST请求报错：TypeError: Converting circular structure to JSON

我尝试用Axios向API发送POST请求，请求体包含Candidates和Items两个嵌套列表的对象，请求时出现了循环引用转JSON的错误，相关代码、请求体和错误信息如下：

请求代码 #

algoController.calculate = async (req, res) => {
  const config = {
    headers:{
      "api-key": process.env.PERSONAL_API_KEY,
      'Content-Type': 'application/json'
    }
  };
  console.log(req.body.data);
  console.log(config);
  res.send( await axios.post(process.env.API_ADDRESS, req.body.data, config)).data
};

请求体日志 #

{
  Candidates: [ { Width: 5000, Length: 5000, Height: 5000, MaxWeight: 1000000 } ],
  Items: [
    {
      Width: 20,
      Length: 16,
      Height: 10,
      Weight: 0,
      TagOrColor: '#00be00',
      Quantity: 10
    }
  ]
}

错误信息 #

C:\Users\tlege\OneDrive\Masaüstü\bindrake\node_modules\express\lib\response.js:1150
    : JSON.stringify(value);
           ^

TypeError: Converting circular structure to JSON
    --> starting at object with constructor 'ClientRequest'
    |     property 'socket' -> object with constructor 'TLSSocket'
    --- property '_httpMessage' closes the circle
    at JSON.stringify (<anonymous>)
    at stringify (C:\Users\tlege\OneDrive\Masaüstü\bindrake\node_modules\express\lib\response.js:1150:12)
    at ServerResponse.json (C:\Users\tlege\OneDrive\Masaüstü\bindrake\node_modules\express\lib\response.js:271:14)
    at ServerResponse.send (C:\Users\tlege\OneDrive\Masaüstü\bindrake\node_modules\express\lib\response.js:162:21)
    at algoController.calculate (C:\Users\tlege\OneDrive\Masaüstü\bindrake\controllers\algoController.js:14:7)
    at processTicksAndRejections (node:internal/process/task_queues:96:5)

解决方案 #

错误核心是括号位置错误：你把.data放在了res.send()的外面，导致res.send()接收的是整个Axios响应对象（包含socket等存在循环引用的属性），而非接口返回的纯数据。

修正后的代码（两种写法任选其一）：

写法一：拆分步骤更清晰 #

algoController.calculate = async (req, res) => {
  const config = {
    headers:{
      "api-key": process.env.PERSONAL_API_KEY,
      'Content-Type': 'application/json'
    }
  };
  console.log(req.body.data);
  console.log(config);
  // 先获取完整响应，再提取数据部分
  const apiResponse = await axios.post(process.env.API_ADDRESS, req.body.data, config);
  res.send(apiResponse.data);
};

写法二：简洁链式调用 #

algoController.calculate = async (req, res) => {
  const config = {
    headers:{
      "api-key": process.env.PERSONAL_API_KEY,
      'Content-Type': 'application/json'
    }
  };
  console.log(req.body.data);
  console.log(config);
  // 将.data移到await的括号内，确保发送的是纯数据
  res.send( (await axios.post(process.env.API_ADDRESS, req.body.data, config)).data );
};

调整后就能正确提取接口返回的纯数据，避免循环引用无法转JSON的问题。

内容的提问来源于stack exchange，提问作者Bot Ellis