node.js - UnhandledPromiseRejectionWarning：错误 [ERR_HTTP_HEADERS_SENT]

Question

UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
[0]     at ServerResponse.setHeader (_http_outgoing.js:526:11)
[0]     at ServerResponse.header (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:771:10)
[0]     at ServerResponse.send (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:170:12)
[0]     at ServerResponse.json (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:267:15)
[0]     at C:\Users\12345\Desktop\Capstone Project\src\controllers\/subjectController.js:35:43
[0]     at processTicksAndRejections (internal/process/task_queues.js:97:5)
[0] (node:7684) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 11)
[0] (node:7684) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
[0]     at ServerResponse.setHeader (_http_outgoing.js:526:11)
[0]     at ServerResponse.header (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:771:10)
[0]     at ServerResponse.send (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:170:12)
[0]     at ServerResponse.json (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:267:15)
[0]     at C:\Users\12345\Desktop\Capstone Project\src\controllers\/subjectController.js:35:43
[0]     at processTicksAndRejections (internal/process/task_queues.js:97:5)
[0] (node:7684) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 12)
[0] (node:7684) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
[0]     at ServerResponse.setHeader (_http_outgoing.js:526:11)
[0]     at ServerResponse.header (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:771:10)
[0]     at ServerResponse.send (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:170:12)
[0]     at ServerResponse.json (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:267:15)
[0]     at C:\Users\12345\Desktop\Capstone Project\src\controllers\/subjectController.js:35:43
[0]     at processTicksAndRejections (internal/process/task_queues.js:97:5)
[0] (node:7684) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 13)
[0] (node:7684) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
[0]     at ServerResponse.setHeader (_http_outgoing.js:526:11)
[0]     at ServerResponse.header (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:771:10)
[0]     at ServerResponse.send (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:170:12)
[0]     at ServerResponse.json (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:267:15)
[0]     at C:\Users\12345\Desktop\Capstone Project\src\controllers\/subjectController.js:35:43
[0]     at processTicksAndRejections (internal/process/task_queues.js:97:5)
[0] (node:7684) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 14)
[0] (node:7684) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
[0]     at ServerResponse.setHeader (_http_outgoing.js:526:11)
[0]     at ServerResponse.header (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:771:10)
[0]     at ServerResponse.send (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:170:12)
[0]     at ServerResponse.json (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:267:15)
[0]     at C:\Users\12345\Desktop\Capstone Project\src\controllers\/subjectController.js:35:43
[0]     at processTicksAndRejections (internal/process/task_queues.js:97:5)
[0] (node:7684) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 15)
[0] (node:7684) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
[0]     at ServerResponse.setHeader (_http_outgoing.js:526:11)
[0]     at ServerResponse.header (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:771:10)
[0]     at ServerResponse.send (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:170:12)
[0]     at ServerResponse.json (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:267:15)
[0]     at C:\Users\12345\Desktop\Capstone Project\src\controllers\/subjectController.js:35:43
[0]     at processTicksAndRejections (internal/process/task_queues.js:97:5)
[0] (node:7684) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 16)
[0] (node:7684) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
[0]     at ServerResponse.setHeader (_http_outgoing.js:526:11)
[0]     at ServerResponse.header (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:771:10)
[0]     at ServerResponse.send (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:170:12)
[0]     at ServerResponse.json (C:\Users\12345\Desktop\Capstone Project\node_modules\express\lib\response.js:267:15)
[0]     at C:\Users\12345\Desktop\Capstone Project\src\controllers\/subjectController.js:35:43
[0]     at processTicksAndRejections (internal/process/task_queues.js:97:5)
[0] (node:7684) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled
[0]     at C:\Users\12345\Desktop\Capstone Project\src\controllers\/subjectController.js:35:43
[0]     at processTicksAndRejections (internal/process/task_queues.js:97:5)
[0] (node:7684) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 19)

router.post('/', passport.authenticate('jwt', { session: false }), (req, res) => {

    for (var i = 0; i < req.body.subjects.length; i++) {

        const subject = req.body.subjects[i];
        const { errors, isValid } = validateSubjectInput(subject);

        // Check validation
        if (!isValid) {
            return res.status(400).json(errors);
        }

        const subjectFields = {};
        for (var key in subject) {
            if (subject[key]) subjectFields[key] = subject[key].trim();
        }
        subjectFields.id = subject.id ? subject.id.trim() : '';

        console.log(subjectFields);

        // See if there is already a subject with the subject ID
        Subject.findOne({ _id: subject._id }).then(subject => {
            if (subject) {
                // Subject already exists
                Subject.findOneAndUpdate(
                    { _id: subject._id },
                    { $set: subjectFields },
                    { new: true }
                ).then(subject => res.json(subject));
            }
            // Subject does not already exist
            else {
                new Subject(subjectFields).save().then(subject => res.json(subject));
            }
        });
    }
});

标签： node.js

Answer 1

最好至少有一个更详细的问题，而不是复制粘贴您的错误消息。

据我所见， express 出现错误，因为您试图多次返回响应。这就是为什么您要创建一个 for 循环并在每次迭代中发送响应。

批量更新的正确方法是检查每个用户的 db 并更新或创建每个操作的结果应存储在数组中。在请求中的所有用户都被迭代之后，然后您在响应中返回结果数组。

在不过多更改代码的情况下，它可能看起来像：

router.post('/', passport.authenticate('jwt', { session: false }), (req, res) => {
    const result = []
    for (var i = 0; i < req.body.subjects.length; i++) {
        const subject = req.body.subjects[i];
        const { errors, isValid } = validateSubjectInput(subject);
        // Check validation
        if (!isValid) {
            result.push(errors);
        } else {
            const subjectFields = {};
            for (let key in subject) {
                if (subject[key]) subjectFields[key] = subject[key].trim();
            }
            subjectFields.id = subject.id ? subject.id.trim() : '';
            console.log(subjectFields);
            // See if there is already a subject with the subject ID
            // with option {new: true} it will create an user if not exists
            Subject.findOneAndUpdate(
                { _id: subject._id },
                { $set: subjectFields },
                { new: true } 
            ).then(subject => result.push(subject));
        }
    }
    res.json(result);
});