PUT 请求后节点 js 服务器崩溃

Question

发出放置请求后，应用程序因错误而崩溃

[nodemon] restarting due to changes...
[nodemon] starting `node index.js`
(node:21666) DeprecationWarning: current URL string parser is deprecated, and will be removed in a future version. To use the new parser, pass option { useNewUrlParser: true } to MongoClient.connect.
(Use `node --trace-deprecation ...` to show where the warning was created)
Server up and running
(node:21666) DeprecationWarning: Mongoose: `findOneAndUpdate()` and `findOneAndDelete()` without the `useFindAndModify` option set to false are deprecated. See: https://mongoosejs.com/docs/deprecations.html#findandmodify
node:internal/process/promises:227
          triggerUncaughtException(err, true /* fromPromise */);
          ^

Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
    at new NodeError (node:internal/errors:329:5)
    at ServerResponse.setHeader (node:_http_outgoing:572:11)
    at ServerResponse.header (/Users/kayode/Desktop/learn-mern/auth/node_modules/express/lib/response.js:771:10)
    at ServerResponse.json (/Users/kayode/Desktop/learn-mern/auth/node_modules/express/lib/response.js:264:10)
    at ServerResponse.send (/Users/kayode/Desktop/learn-mern/auth/node_modules/express/lib/response.js:158:21)
    at /Users/kayode/Desktop/learn-mern/auth/routes/users.js:36:24
    at processTicksAndRejections (node:internal/process/task_queues:94:5) {
  code: 'ERR_HTTP_HEADERS_SENT'
}
[nodemon] app crashed - waiting for file changes before starting...

这是我的代码...

const router = require('express').Router();
const User = require('../models/User')

router.put('/:email', async (req, res, next) => {
    res.send(req.params._id)
    let email = req.params.email;
    let user = {
        name: req.body.name,
        email: req.body.email,
        password: req.body.password
    }

    try {
        await User.findOneAndUpdate(email, user);
        res.status(200).send(JSON.stringify('200'));
        console.log('Here first')
    } catch (err) {
        res.status(400).send(err) //not commented
    }
})

module.exports = router;

但是，如果我尝试发出另一个请求（使用邮递员），没有刷新服务器，它说发送了一个错误无法发送请求

但是话又说回来，在第 36 行，“在 /Users/kayode/Desktop/learn-mern/auth/routes/users.js:36:24”，其中写着 res.status(400).send(err) //not commented 如果我注释掉该行（即不是 return 错误），PUT 请求将会成功，之后的另一个请求也可以在不刷新或重新启动服务器的情况下工作。

我知道我可以只注释掉那一行然后继续，但我需要知道发生了什么，谢谢！

Answer 1

您正在请求的开头发送响应，并尝试在请求的末尾再次发送（第 5 行）。

const router = require('express').Router();
const User = require('../models/User')

router.put('/:email', async (req, res, next) => {
    let email = req.params.email;
    let user = {
        name: req.body.name,
        email: req.body.email,
        password: req.body.password
    }

    try {
        await User.findOneAndUpdate(email, user);
        res.status(200).send(JSON.stringify('200'));
        console.log('Here first')
    } catch (err) {
        res.status(400).send(err) //not commented
    }
})

module.exports = router;

PUT 请求后节点 js 服务器崩溃

Node js server crashes after PUT request

put

mongoose

mongodb

node.js

express