Can't retrieve data from mongoDB with Node.js

Question

I'm pretty new in Node.js and I have this project. Basically I have some data sits in a mongoDB collection("data") and I'm trying to get that data and display it on the browser.

Here is what I've got so far;

    var MongoClient = require('mongodb').MongoClient
        ,format = require('util').format;
    var sys = require ("sys");
    my_http = require("http");

      my_http.createServer(function(request, response){
         sys.puts("Touched !!");
         response.writeHeader(200, {"Content-Type": "text/plain"});
         response.write(extractData()).toString();
         response.end();
     }).listen(8080);
sys.puts("Server is running on 8080"); // Server kicks in...np

function extractData(){

    MongoClient.connect('mongodb://127.0.0.1:27017/mongoDB', function(err, db){
        if (err){
            console.log("Can't Connect to DB !!");
        }else {
            console.log("Connected to DB !!");   // connects to DB, np
            db.data.find({}, function(err, data){  // .find is the problem
                if (err || !data) console.log("No Data Found");
                else data.forEach(function (data){
                    console.log(data);
                });
            }).toArray();
        }
    });
}

And after I run "node server.js" and refresh the already open localhost:8080, I get this;

Server is running on 8080
Touched !!
Touched !!
Connected to DB !!

d:\Projects\SCRIPTS\mdp.scripts.testing-tools\jsFinderWmongoDB\node_modules\mongodb\lib\mongodb\mongo_client.js:475
          throw err
                ^
TypeError: Cannot call method 'find' of undefined
    at d:\Projects\SCRIPTS\mdp.scripts.testing-tools\jsFinderWmongoDB\server.js:21:21
    at d:\Projects\SCRIPTS\mdp.scripts.testing-tools\jsFinderWmongoDB\node_modules\mongodb\lib\mongodb\mongo_client.js:4
72:11
    at process._tickCallback (node.js:415:13)

Don't understand why there is a problem with .find() and of course can't display any data...

Any ideas?

Edit:

Well, we are certainly getting somewhere. I've made some changes.

Current code:

function extractData(){

MongoClient.connect('mongodb://127.0.0.1:27017/mongoDB', function(err, db){
        if (err){
            console.log("Can't Connect to DB !!");
        }else {
            sys.puts("Connected to DB !!");   // connects to DB, np
            db.collection('data').find({}, function(err, data){  
                if (err || !data) console.log("No Data Found");
                //else db.collection('data').forEach(function (data){
                //    console.log(data);
                //});
            });//.toArray();
        }
    });
}

Browser response is "undefined"

I'm guessing "extractData" function is NOT returning something legit. Therefore the collection set "data" is returning empty.

And yes I've checked one more time, I have data in the dataset.

so db.data is undefined, are you sure you don't want db.collection('data') or something like that ? — adeneo
– adeneo, Commented Feb 27, 2015 at 17:05
Well, we are certainly getting somewhere. I've made some changes. — Leustad
– Leustad, Commented Feb 27, 2015 at 17:52

David Alasow · Accepted Answer · 2015-02-27 19:22:59Z

1

You need to set a collection to use before you can do anything with it.

var collection = db.collection('data');
collection.find({},function(err,data){
    console.log(data);
});

Would be how you do it.

Update ** This was how I did my first mongoDB stuff using express Might help you.

var mongo = require('mongodb');
var monk = require('monk');
var db = monk('localhost:27017/nodetest1');

app.get('/userlist', function(req, res) {
var db = req.db;
var collection = db.get('usercollection');
 collection.find({},{},function(e,docs){
    res.render('userlist', {
        "userlist" : docs
    });
 });
});

edited Feb 27, 2015 at 19:22

answered Feb 27, 2015 at 18:04

David Alasow

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1 Comment

Leustad Over a year ago

That worked, thank you. But the browser still displaying "undefined".

Leustad · Accepted Answer · 2015-02-27 18:33:33Z

I get the details about the stored data when do console.log(data);

Here is a glimpse of it

Server is running on 8080
Touched !!
Connected to DB !!
{ db: 
   { domain: null,
     _events: {},
     _maxListeners: 10,
     databaseName: 'mongoDB',
     serverConfig: 
      { domain: null,
        _events: {},
        _maxListeners: 10,
        auth: [Getter],
        _callBackStore: [Object],
        _commandsStore: [Object],
        _dbStore: [Object],
        host: '127.0.0.1',
        port: 27017,
        options: [Object],
        internalMaster: true,
        connected: true,
        poolSize: 5,
        disableDriverBSONSizeCheck: false,
        _used: true,
        replicasetInstance: null,
        emitOpen: false,
        ssl: false,
        sslValidate: false,
        sslCA: null,
        sslCert: undefined,
        sslKey: undefined,
        sslPass: undefined,
        serverCapabilities: [Object],
        name: '127.0.0.1:27017',
        socketOptions: [Object],
        logger: [Object],
        eventHandlers: [Object],
        _serverState: 'connected',
        _state: [Object],
        recordQueryStats: false,
        socketTimeoutMS: [Getter/Setter],
        _readPreference: [Object],
        db: [Circular],
        dbInstances: [Object],
        connectionPool: [Object],
        isMasterDoc: [Object] },
     options: 
      { read_preference_tags: null,
        read_preference: 'primary',
        url: 'mongodb://127.0.0.1:27017/mongoDB',
        native_parser: true,
        readPreference: [Object],
        safe: false,
        w: 1 },
     _applicationClosed: false,
     slaveOk: false,
     bufferMaxEntries: -1,
     native_parser: true,
     bsonLib: 
      { BSON: [Object],
        Long: [Object],
        ObjectID: [Object],
        DBRef: [Object],
        Code: [Object],
        Timestamp: [Object],
        Binary: [Object],
        Double: [Object],
        MaxKey: [Object],
        MinKey: [Object],
        Symbol: [Object] },
     bson: { promoteLongs: true },
     bson_deserializer: 
      { Code: [Object],
        Symbol: [Object],
        BSON: [Object],
        DBRef: [Object],
        Binary: [Object],
        ObjectID: [Object],
        Long: [Object],
        Timestamp: [Object],
        Double: [Object],
        MinKey: [Object],
        MaxKey: [Object],
        promoteLongs: true },
     bson_serializer: 
      { Code: [Object],
        Symbol: [Object],
        BSON: [Object],
        DBRef: [Object],
        Binary: [Object],
        ObjectID: [Object],
        Long: [Object],
        Timestamp: [Object],
        Double: [Object],
        MinKey: [Object],
        MaxKey: [Object],
        promoteLongs: true },
     _state: 'connected',
     pkFactory: 
      { [Function: ObjectID]
        index: 16043018,
        createPk: [Function: createPk],
        createFromTime: [Function: createFromTime],
        createFromHexString: [Function: createFromHexString],
        isValid: [Function: isValid],
        ObjectID: [Circular],
        ObjectId: [Circular] },
     forceServerObjectId: false,
     safe: false,
     notReplied: {},
     isInitializing: true,
     openCalled: true,
     commands: [],
     logger: { error: [Function], log: [Function], debug: [Function] },
     tag: 1425061857066,
     eventHandlers: 
      { error: [],
        parseError: [],
        poolReady: [],
        message: [],
        close: [] },
     serializeFunctions: false,
     raw: false,
     recordQueryStats: false,
     retryMiliSeconds: 1000,
     numberOfRetries: 60,
     readPreference: { _type: 'ReadPreference', mode: 'primary', tags: undefined } },
  collection:

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