TypeError: undefined is not a function - Node.js & MongoDB

Question

For some reason, functions called on my cursor object are not found. Here's my code:

var db = req.db;
var goalscollection = db.get('goalscollection');
var collection = db.get('hoursburnedcollection');

var cursor = collection.find({goal: selectedgoal}, console.log);  
// the line above prints the correct cursor object

var doc = cursor.hasNext() ? cursor.next() : null;  //line 51
// the line above gives an error

Here's the error:

TypeError: undefined is not a function
at /Users/chrispark/Projects/LifeTool/node/routes/index.js:51:27
at Layer.handle [as handle_request] (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/layer.js:95:5)
at next (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/route.js:131:13)
at Route.dispatch (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/route.js:112:3)
at Layer.handle [as handle_request] (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/layer.js:95:5)
at /Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/index.js:277:22
at Function.process_params (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/index.js:330:12)
at next (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/index.js:271:10)
at Function.handle (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/index.js:176:3)
at router (/Users/chrispark/Projects/LifeTool/node/node_modules/express/lib/router/index.js:46:12)

Is there something I'm missing? Thanks in advance.

Answer 1

From where myCursor comes?

Use cursor instead of myCursor :

var doc = cursor.hasNext() ? cursor.next() : null;  //line 51

Answer 2

If you provide a callback function to find , the cursor will only be provided to the callback and not returned. So remove the console.log parameter and you'll get the cursor.

Also, next doesn't return the next doc, it provides back to the caller via an async callback.

var cursor = collection.find({goal: selectedgoal});
if (cursor.hasNext()) {
    cursor.next(function(err, doc) {
        console.log(doc);
    });
}

Answer 3

Are you sure about the error line number ?

I would say the error is comming from those lines :

var goalscollection = db.get('goalscollection');
var collection = db.get('hoursburnedcollection');

I can't find any method get in driver API. It should be db.collection() :

var goalscollection = db.collection('goalscollection');
var collection = db.collection('hoursburnedcollection');