Node.js Express中ERR_HTTP_HEADERS_SENT错误求助

错误信息 #

node:internal/errors:464
    ErrorCaptureStackTrace(err);
    ^

Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
    at new NodeError (node:internal/errors:371:5)
    at ServerResponse.setHeader (node:_http_outgoing:576:11)
    at ServerResponse.header (C:\Users\ND\StudioProjects\pos\node_modules\express\lib\response.js:794:10)
    at ServerResponse.send (C:\Users\ND\StudioProjects\pos\node_modules\express\lib\response.js:174:12)
    at ServerResponse.json (C:\Users\ND\StudioProjects\pos\node_modules\express\lib\response.js:278:15)
    at deleteAddItem (file:///C:/Users/ND/StudioProjects/pos/controller/bill/addItem.controller.js:41:21)
    at processTicksAndRejections (node:internal/process/task_queues:96:5) {
  code: 'ERR_HTTP_HEADERS_SENT'
}

相关代码 #

控制器代码 #

const deleteAddItem = async (req, res) => {
  try {
    const getItem = req.body;
    const deleteItem = await AddItem.findOneAndDelete(getItem);
    if (!deleteItem) res.status(203).json({ msg: "No bill available" });
    return res.status(202).json({ msg: "Bill Deleted" });
  } catch (error) {
    console.error(error);
    res.status(500).json({ msg: "Internal Server Error deleteAddItem", error });
  }
};

路由配置 #

billRouter.delete("/deleteAddItem", deleteAddItem);

问题根源 #

这个错误的核心是同一个请求中多次向客户端发送响应。

当!deleteItem条件成立时，代码执行res.status(203).json(...)已经发送了一次响应，但因为没有用return终止函数，后续代码会继续执行return res.status(202).json(...)，导致第二次尝试发送响应，触发ERR_HTTP_HEADERS_SENT错误。

修复方案 #

在条件分支发送响应后，用return终止函数，避免后续代码继续执行：

const deleteAddItem = async (req, res) => {
  try {
    const getItem = req.body;
    const deleteItem = await AddItem.findOneAndDelete(getItem);
    if (!deleteItem) {
      return res.status(203).json({ msg: "No bill available" });
    }
    return res.status(202).json({ msg: "Bill Deleted" });
  } catch (error) {
    console.error(error);
    res.status(500).json({ msg: "Internal Server Error deleteAddItem", error });
  }
};

也可以用else分支区分逻辑，达到同样效果：

const deleteAddItem = async (req, res) => {
  try {
    const getItem = req.body;
    const deleteItem = await AddItem.findOneAndDelete(getItem);
    if (!deleteItem) {
      res.status(203).json({ msg: "No bill available" });
    } else {
      res.status(202).json({ msg: "Bill Deleted" });
    }
  } catch (error) {
    console.error(error);
    res.status(500).json({ msg: "Internal Server Error deleteAddItem", error });
  }
};

内容的提问来源于stack exchange，提问作者MYOUSUFFS