关于NodeJs为啥要用mongoose操作mongodb
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参考技术A 也不一定要用mongoose操作,还有别的mongodb驱动,用它是因为它满足你操作mongodb的需求。NodeJS/Express/Mongoose 出错 Can't set headers after they are sent
【中文标题】NodeJS/Express/Mongoose 出错 Can\'t set headers after they are sent【英文标题】:NodeJS/Express/Mongoose get error Can't set headers after they are sentNodeJS/Express/Mongoose 出错 Can't set headers after they are sent 【发布时间】:2014-12-23 15:19:25 【问题描述】:我正在使用 MEAN 堆栈和 Mongoose 来查询 MongoDB 上的数据。第一次调用 /api/Validations 很好,但第二次,它总是得到这个错误:
这是我的代码,server.js:
var express = require('express')
, app = express()
, bodyParser = require('body-parser')
, breezeRoutes = require('./breeze-routes')
, controller = require('./controller')
, compress = require('compression')
, cors = require('cors')
, errorHandler = require('./errorHandler')
, favicon = require('static-favicon')
, fileServer = require('serve-static')
, http = require('http')
, isDev = app.get('env') === 'development'
, logger = require('morgan')
, port = process.env["PORT"] || 4000;
app.use(favicon());
app.use(logger('dev'));
app.use(compress());
app.use(bodyParser()); // both json & urlencoded
app.use(cors()); // enable ALL CORS requests
controller.init(app); // Configure routes for REST API
app.use(errorHandler);
// create server (in case interested in socket.io)
var server = http.createServer(app);
// Start listening for HTTP requests
server.listen(port); // app.listen( port ); // if we weren't using 'server'
console.log('\nListening on port ' + port);
controller.js:
(function (controller)
var mongooseDB = require("./mongooseDB");
controller.init = configureRoutes;
function configureRoutes(app)
app.get('/api/Validations', getValidations);
function getValidations(req, res, next)
mongooseDB.getValidations(makeResponseHandler(res, next));
function makeResponseHandler(res, next)
// returns a function that handles response from a Breeze Mongo query or save
return function (err, results)
if (err)
next(err);
else
// Prevent browser from caching results of API data requests
//res.setHeader('Cache-Control', 'no-cache, private, no-store, must-revalidate, max-stale=0, post-check=0, pre-check=0');
//res.setHeader("Content-Type:", "application/json");
res.send(JSON.stringify(results));
res.end();
)(module.exports)
mongooseDB.js
(function (mongooseDB)
var schema = require("./schema");
var validator = require("./validator");
var mongoUrl = 'mongodb://localhost:27017/dpt';
var mongoose = require('mongoose');
var Validations = mongoose.model('Validations', schema.ValidationSchema);
mongooseDB.getValidations = function (next)
mongoose.connect(mongoUrl);
mongoose.connection.on('open', function ()
var query = Validations.find();
query.exec(function (err, docs)
mongoose.disconnect();
if (err)
next(err, null);
else
next(null, docs);
);
);
;
)(module.exports)
validationSchema.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var validationSchema = new Schema(
ValidationID: type: String, index: 1, required: true, unique: true ,
Integer: type: Number, required: true ,
String: String,
Date: Date,
BeforeDate: Date,
AfterDate: Date,
Age: Number,
CreditCard : Number,
Email: String,
Phone: String,
URL: String,
Zip: String,
StartsWithDPT: String,
ContainsDPT: String
, collection: 'Validations' );
exports.ValidationSchema = validationSchema;
我在堆栈溢出时阅读了所有“发送后无法设置标题”并尝试应用一些方法但没有运气。 请帮帮我。
更新 1:
我认为这是 Mongoose 的问题,因为在我将其更改为使用 MongoDB 后,它工作正常: (函数(数据库) var MongoClient = require('mongodb').MongoClient;
database.getDb = getDb;
database.getValidations = getValidations;
var db = null;
// todo: get from configuration
var mongoUrl = 'mongodb://localhost:27017/dpt';
var mongoOptions =
server: auto_reconnect: true
;
function getDb(next)
if (db)
next(null, db);
else
MongoClient.connect(mongoUrl, mongoOptions, function (err, theDb)
if (err)
err.message = (err.message || '') + '. Is the MongoDb server running?';
next(err, null);
else
db = theDb;
next(null, db);
);
function getValidations(next)
getDb(function (err, data)
if (err)
err.message = (err.message || '') + '. Is the MongoDb server running?';
next(err, null);
else
data.collection("Validations").find().toArray(function (err1, results)
next(null, results);
);;
);
)(module.exports)
现在我可以根据需要多次调用 /api/Validations,但这个问题仍然存在,因为这个项目需要 Mongoose。
【问题讨论】:
【参考方案1】:而不是这个:
return function (err, results)
if (err)
next(err);
else
// Prevent browser from caching results of API data requests
//res.setHeader('Cache-Control', 'no-cache, private, no-store, must-revalidate, max-stale=0, post-check=0, pre-check=0');
//res.setHeader("Content-Type:", "application/json");
res.send(JSON.stringify(results));
res.end();
使用这个
return function (err, results)
if (err)
next(err);
else
// Prevent browser from caching results of API data requests
//res.setHeader('Cache-Control', 'no-cache, private, no-store, must-revalidate, max-stale=0, post-check=0, pre-check=0');
//res.setHeader("Content-Type:", "application/json");
res.end(JSON.stringify(results));
【讨论】:
感谢@Suburaj,但实际上,这是我的第一种方法,但没有奏效。我仍然遇到这个问题。我更新了我的问题 @Quoc Nguyen 代码现在正在运行???如果这有用,请不要忘记接受答案..res.send
无论如何都会调用res.end
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