node.js - 如何在Node.js应用中输出mongodb集合以获取响应

我正在使用Cloude 9环境开发我的nodejs应用程序。在那我写了代码来连接到mongodb数据库。我成功连接到数据库并将记录添加到集合中。

现在，我想发送回收集信息。但是使用res.send(collectionInfo);不起作用。

让我知道我应该如何实现

下面是我的server.js文件的代码

var Db = require('mongodb').Db;
var http = require('http');
var path = require('path');

var async = require('async');
var socketio = require('socket.io');
var express = require('express');
var ejs = require('ejs');

var app = express();

var helpers = require('express-helpers')

var MongoClient = require('mongodb').MongoClient;
var Server = require('mongodb').Server;
var db;

helpers(app);

var bodyParser = require('body-parser');

app.use(bodyParser.json()); // for parsing application/json
app.use(bodyParser.urlencoded({extended: true})); // for parsing application/x-www-form-urlencoded
var server = http.Server(app);

server.listen(process.env.PORT || 3000, process.env.IP || "0.0.0.0", function () {
    var addr = server.address();
    console.log("Chat server listening at", addr.address + ":" + addr.port);
});
app.use(express.static(__dirname + '/public'));
app.set('views', __dirname + '/public/views');
app.engine('html', require('ejs').renderFile);
app.set('view engine', 'html');

//app.use(express.static(__dirname + '/client'));
app.use(express.static(path.join(__dirname, '/client')));

// MongoDB Connection
app.use(function(req, res, next) {
    next();
})

app.get('/monogdb', function (req, res) {
    res.render('monogdb.ejs');
});

app.post('/ajax-mongo-connect', function (req, res) {
    var mongoClient = new MongoClient(new Server('localhost', 27017));
    mongoClient.open(function(err, mongoClient) {
        if(err){
            console.log(err);
        }else{

            var db = mongoClient.db("mydb");
            db.createCollection("students", { name : req.body.nm, description : req.body.desc, location : req.body.loc } );
            console.log('database connected',db);
            var collectionInfo = db.collection("students");
            mongoClient.close();
            //res.setHeader('Content-Type', 'application/json');
            res.send(collectionInfo);

        }
    })
})

根据@Roman Sachenko的回答，我尝试使用
res.send(collectionInfo.toJSON());，但出现以下错误

/home/ubuntu/workspace/node_modules/mongodb/lib/mongodb/db.js:299
throw err;
^
TypeError: Object #<Collection> has no method 'toJSON'
at /home/ubuntu/workspace/server.js:66:41
at MongoClient.open
(/home/ubuntu/workspace/node_modules/mongodb/lib/mongodb/mongo_client.js:103:5)
 at Db.open (/home/ubuntu/workspace/node_modules/mongodb/lib/mongodb/db.js:296:11)
 at process._tickCallback (node.js:442:13)

并使用res.send({data: collectionInfo});给出错误

home/ubuntu/workspace/node_modules/mongodb/lib/mongodb/db.js:299
throw err;
     ^
TypeError: Converting circular structure to JSON
at Object.stringify (native)
at ServerResponse.res.json (/home/ubuntu/workspace/node_modules/express/lib/response.js:185:19)
at ServerResponse.res.send (/home/ubuntu/workspace/node_modules/express/lib/response.js:117:21)
at /home/ubuntu/workspace/server.js:67:21
at MongoClient.open (/home/ubuntu/workspace/node_modules/mongodb/lib/mongodb/mongo_client.js:103:5)
at Db.open (/home/ubuntu/workspace/node_modules/mongodb/lib/mongodb/db.js:296:11)
at process._tickCallback (node.js:442:13)

最佳答案

尝试返回以下内容：res.status(200).json({'myCollection' : collectionInfo});。

您可以找到有关快速回复here的更多详细信息

更新：

在解释了详细信息之后，请看下面的代码：

app.post('/ajax-mongo-connect', function (req, res) {
    var mongoClient = new MongoClient(new Server('localhost', 27017));
    mongoClient.open(function(err, mongoClient) {
        if(err){
            console.log(err);
            res.status(500).json({message : 'OMG, an error occurred'});
        }else{
            var db = mongoClient.db("mydb");
            db.createCollection("students", { name : req.body.nm, description : req.body.desc, location : req.body.loc } );
            console.log('database connected',db);
            var collectionInfo = db.collection("students");
            // Here we will find all students
            collectionInfo.find({}).toArray(function(err, students) {
               // so now, we can return all students to the screen.
               res.status(200).json({'myCollection' : students});
            }
        }
    })
})

干杯!