錯誤[ERR_HTTP_HEADERS_SENT]：在將標頭發送到客戶端后無法設定標頭-如何解決

它按預期在郵遞員中顯示錯誤 json，但之后它崩潰了。

• 發送成功 json 后不會崩潰

資料庫連接 POST /api/signup 200 84.443 ms - 27 events.js:377 throw er; // 未處理的“錯誤”事件 ^

Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
at new NodeError (internal/errors.js:322:7)
at ServerResponse.setHeader (_http_outgoing.js:561:11)
at ServerResponse.header (/home/aman/Projects/Discover/discover_blog/backend/node_modules/express/lib/response.js:794:10)
at ServerResponse.send (/home/aman/Projects/Discover/discover_blog/backend/node_modules/express/lib/response.js:174:12)
at ServerResponse.json (/home/aman/Projects/Discover/discover_blog/backend/node_modules/express/lib/response.js:278:15)
at /home/aman/Projects/Discover/discover_blog/backend/controllers/auth.js:22:30
at /home/aman/Projects/Discover/discover_blog/backend/node_modules/mongoose/lib/model.js:5004:18
at processTicksAndRejections (internal/process/task_queues.js:77:11)

在函式實體上發出“錯誤”事件：在 /home/aman/Projects/Discover/discover_blog/backend/node_modules/mongoose/lib/model.js:5006:15 在 processTicksAndRejections (internal/process/task_queues.js:77: 11）{代碼：'ERR_HTTP_HEADERS_SENT'}

//

const User = require("../models/user");
const shortId = require("shortid");
//
const signup = (req, res) => {
  const { name, email, password } = req.body;
  User.findOne({ email: email }).exec((err, user) => {
    if (user) {
      return res.status(400).json({
        error: "Email is taken ",
      });
    }
  });

  let username = shortId.generate();
  let profile = `${process.env.CLIENT_URL}/profile/${username}`;
  let newUser = new User({ name, email, password, profile, username });

  newUser.save((err, user) => {
    if (err) {
      return res.status(400).json({
        error: err,
      });
    }
    return res.json({
      message: "Signup is successfull! Please signin",
      user: user,
    });
  });
};

module.exports = { signup };

uj5u.com熱心網友回復：

您運行newUser.save得太早了 - 您需要等到.findOne完成，否則您將發送初始 400 狀態（電子郵件已被接收），然后發送一個帶有注冊結果的狀態。我還建議不要忽略可能的.findOne錯誤。

const signup = (req, res) => {
    const { name, email, password } = req.body;
    User.findOne({ email: email }).exec((err, user) => {
        if (err) {
            return res.status(400).json({
                error: err,
            });
        }
        if (user) {
            return res.status(400).json({
                error: "Email is taken ",
            });
        }
        const username = shortId.generate();
        const profile = `${process.env.CLIENT_URL}/profile/${username}`;
        const newUser = new User({ name, email, password, profile, username });

        newUser.save((err, user) => {
            if (err) {
                return res.status(400).json({
                    error: err,
                });
            }
            return res.json({
                message: "Signup is successfull! Please signin",
                user: user,
            });
        });
    });
};

標籤：节点.js 表示

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