node.js - 使用 Node/Express 发送后不断收到 "Can' t set headers

Question

构建 Node/Express API 时，我不断收到“发送后无法设置 header ”的消息。

问题是我在响应发送到任何地方后没有设置 header 。我总是调用 res.status(xxx).json({}) 来关闭任何条件。

路线

const router = require('express').Router();
router.get('/password/validate/:hash', PasswordController.validate);
router.post('/password/update', PasswordController.update);

Controller

这是发生错误的地方。我专门调用验证请求。

// Import node packages
const mongoose = require('mongoose');
const Password = require('../models/password');
const User = require('../models/user');
const bcrypt = require('bcryptjs');
const moment = require('moment');
const string = require('../middleware/string_functions')

exports.update = (req, res, next) => {
    User.findOne({ email: req.body.email })
        .exec()
        .then(user => {
            if (!user) {
                res.status(401).json({
                    message: 'Cannot retrieve account'
                })
            }
            const expiry = moment().add(30, 'seconds');
            const unique_string = string.generate_random(32);
            const url_hash = string.base64_encode(unique_string +':'+ user._id);
            bcrypt.hash(unique_string, 10, (err, hash) => {
                if (err) {
                    res.status(500).json({ 
                        error: err.message
                    })
                }
                const query = { user_id: user._id }
                const newData = {
                    hash,
                    expiry
                }
                Password.findOneAndUpdate(query, newData, { upsert: true, new: true })
                    .exec()
                    .then(request => {
                        res.status(201).json({
                            message: 'success',
                            url: 'localhost:8081/users/password/validate/' + url_hash,
                            data: request
                        })
                    })
                    .catch(err => {
                        res.status(500).json({
                            error: err.message
                        })
                    })
            })
        })
        .catch(err => {
            res.status(500).json({
                error: err.message
            })
        })
}

exports.validate = (req, res, next) => {
    if (!req.params.hash) {
        res.status(500).json({
            error: 'Missing hash'
        })
    }
    const data = string.base64_decode(req.params.hash).split(':');
    console.log(data)
    Password.findOne({ user_id: data[1] })
        .exec()
        .then(request => {
            if (!request) {
                res.status(404).json({
                    message: 'Change request not found or expired'
                })
            }
            bcrypt.compare( data[0], request.hash, (err, result) => {
                if (err) {
                    res.status(500).json({
                        error: err.message
                    })
                }
                if (result) {
                    if (moment().isAfter(request.expiry)) {
                        res.status(401).json({
                            message: 'Time has expired'
                        })
                    }
                    res.status(200).json({
                        message: 'Hash validation successful'
                    })
                }
                res.status(500).json({
                    error: 'Something went wrong'
                })
            })
        })
        .catch(err => {
            res.status(500).json({
                error: err.message
            })
        })
}

控制台错误

_http_outgoing.js:494
    throw new Error('Can\'t set headers after they are sent.');
    ^

Error: Can't set headers after they are sent.
    at validateHeader (_http_outgoing.js:494:11)
    at ServerResponse.setHeader (_http_outgoing.js:501:3)
    at ServerResponse.header (/Users/chrislloyd/Development/Projects/happy-hour-api/node_modules/express/lib/response.js:767:10)
    at ServerResponse.send (/Users/chrislloyd/Development/Projects/happy-hour-api/node_modules/express/lib/response.js:170:12)
    at ServerResponse.json (/Users/chrislloyd/Development/Projects/happy-hour-api/node_modules/express/lib/response.js:267:15)
    at bcrypt.compare (/Users/chrislloyd/Development/Projects/happy-hour-api/api/controllers/passwords.js:83:22)
    at /Users/chrislloyd/Development/Projects/happy-hour-api/node_modules/bcryptjs/dist/bcrypt.js:297:21
    at /Users/chrislloyd/Development/Projects/happy-hour-api/node_modules/bcryptjs/dist/bcrypt.js:1353:21
    at Immediate.next [as _onImmediate] (/Users/chrislloyd/Development/Projects/happy-hour-api/node_modules/bcryptjs/dist/bcrypt.js:1233:21)
    at runCallback (timers.js:789:20)
    at tryOnImmediate (timers.js:751:5)
    at processImmediate [as _immediateCallback] (timers.js:722:5)

更新的示例

exports.update = (req, res, next) => {
    // Check if hash value exists
    if (!req.params.hash) {
        res.status(500).json({
            error: 'Missing hash value'
        });
        return;
    }
    // Check if password and confirmation are the same
    if (req.body.password != req.body.passwordConfirmation) {
        res.status(401).json({
            message: 'Password confirmation does not match'
        });
        return;
    }
    // Decode and split hash and user id into array
    const data = string.base64_decode(req.params.hash).split(':');
    // Find record that contains user id
    Password.findOne({ user_id: data[1] })
        .exec()
        .then(request => {
            console.log(request)
            // Throw 404 error if record is not found
            if (!request) {
                return res.status(404).json({
                    message: 'Password change request doest not exist or timed out'
                });
            }
            // Check if change request has expired
            if (moment().isAfter(request.expiry)) {
                res.status(401).json({
                    message: 'Password change request expired',
                    request: {
                        request: 'http://localhost:3001/users/password/request'
                    }
                });
                // Delete expired record
                Password.remove({ _id: request._id })
                    .exec()
                    .catch(err => {
                        res.status(500).json({
                            error: err.message
                        });
                    });
                return;
            }
            // Compare hash value from encoded string to encrypted hash value in database
            console.log(mongoose.Types.ObjectId(request.user_id))
            bcrypt.compare( data[0], request.hash, (err, result) => {
                // Bcrypt error performing comparison
                if (err) {
                    res.status(500).json({
                        error: err.message
                    });
                    return;
                }
                // Check if result is true
                if (result) {
                    // Find user record matching request.user_id and update password
                    User.findOneAndUpdate({ _id: mongoose.Types.ObjectId(request.user_id) }, {$set: { password: req.body.password  }}, {new: true}, (err, user) => {
                        console.log(user)
                        // Error finding and updating user record
                        if (err) {
                            res.status(500).json({
                                error: err.message
                            });
                            return;
                        }
                        // If returned user account is not null
                        if (user) {
                            res.status(200).json({
                                message: 'Password updated',
                                user
                            });
                            return;
                        }
                        // Could not find user record
                        res.status(404).json({
                            message: 'Could not find user account to update'
                        });
                        return;
                    })
                }
                // Catch all error
                res.status(500).json({
                    error: 'Something went wrong'
                });
                return;
            })
        })
        .catch(err => {
            res.status(500).json({
                error: err.message
            });
            return;
        });
}

Answer 1

当您向同一请求发送多个响应时，会导致该特定错误。

您似乎认为，一旦您执行 res.status(...).json(...) ，您的函数就会返回并停止执行。它不是。 res.json() 只是常规函数调用。它根本不会改变函数中的控制流(除非它抛出异常)。成功调用 res.json() 后，您的函数将继续执行后面的代码行。

您需要的是每次发送响应后有一个 return 语句(如果您的函数中有任何其他代码可以执行并发送另一个响应)，以便您的函数不会继续执行并发送另一响应，或者您可以将响应括在 if/else 语句中，这样就不会执行发送多个响应。

这是一个修复版本，添加了 5 个 return 语句，以防止在发送响应后执行其余代码，并防止您向同一请求发送多个响应。每个添加都用 ==> 添加 进行注释:

// Import node packages
const mongoose = require('mongoose');
const Password = require('../models/password');
const User = require('../models/user');
const bcrypt = require('bcryptjs');
const moment = require('moment');
const string = require('../middleware/string_functions')

exports.update = (req, res, next) => {
    User.findOne({ email: req.body.email })
        .exec()
        .then(user => {
            if (!user) {
                res.status(401).json({
                    message: 'Cannot retrieve account'
                })
                return;            // <== added
            }
            const expiry = moment().add(30, 'seconds');
            const unique_string = string.generate_random(32);
            const url_hash = string.base64_encode(unique_string +':'+ user._id);
            bcrypt.hash(unique_string, 10, (err, hash) => {
                if (err) {
                    res.status(500).json({ 
                        error: err.message
                    })
                    return;            // <== added
                }
                const query = { user_id: user._id }
                const newData = {
                    hash,
                    expiry
                }
                Password.findOneAndUpdate(query, newData, { upsert: true, new: true })
                    .exec()
                    .then(request => {
                        res.status(201).json({
                            message: 'success',
                            url: 'localhost:8081/users/password/validate/' + url_hash,
                            data: request
                        })
                    })
                    .catch(err => {
                        res.status(500).json({
                            error: err.message
                        })
                    })
            })
        })
        .catch(err => {
            res.status(500).json({
                error: err.message
            })
        })
}

exports.validate = (req, res, next) => {
    if (!req.params.hash) {
        res.status(500).json({
            error: 'Missing hash'
        })
    }
    const data = string.base64_decode(req.params.hash).split(':');
    console.log(data)
    Password.findOne({ user_id: data[1] })
        .exec()
        .then(request => {
            if (!request) {
                res.status(404).json({
                    message: 'Change request not found or expired'
                })
                return;            // <== added
            }
            bcrypt.compare( data[0], request.hash, (err, result) => {
                if (err) {
                    res.status(500).json({
                        error: err.message
                    })
                    return;            // <== added
                }
                if (result) {
                    if (moment().isAfter(request.expiry)) {
                        res.status(401).json({
                            message: 'Time has expired'
                        })
                    }
                    res.status(200).json({
                        message: 'Hash validation successful'
                    })
                    return;            // <== added
                }
                res.status(500).json({
                    error: 'Something went wrong'
                })
            })
        })
        .catch(err => {
            res.status(500).json({
                error: err.message
            })
        })
}