Callback is not a function in mongoose.find({})

Question

I am new to Node.js and mongoose, i am trying to query objects from a mongo collection using find({}) and the function is as follows :

schema.statics.listAllQuizes = function listAllQuizes(){
Model.find({},function(err,quizes,cb){
    if(err){
        return cb(err);
    }else if(!quizes){
        return cb();
    }
    else {
        return cb(err,quizes);
    }
});};

But when i call this function i get an error saying

        return cb(err,quizes);
               ^
        TypeError: cb is not a function

I am stuck at this point, can someone please help me with this, thanks in advance.

Possible duplicate of [How do I return the response from an asynchronous call?](http://stackoverflow.com/questions/14220321/how-do-i-return-the-response-from-an-asynchronous-call). Which means you don't `return` function results, you "use" them by providing a callback to act on the value. — Blakes Seven, Feb 06 '16 at 06:44
i am handling the response in cb (); i am not simply returning quizes or error — kumarD, Feb 06 '16 at 06:47

robertklep · Accepted Answer · 2016-02-06T06:59:55.450

5

The callback should an argument to listAllQuizes, not an argument to the anonymous handler function.

In other words:

schema.statics.listAllQuizes = function listAllQuizes(cb) {
  Model.find({}, function(err, quizes) {
    if (err) {
      return cb(err);
    } else if (! quizes) {
      return cb();
    } else {
      return cb(err, quizes);
    }
  });
};

Which, logically, is almost the same as this:

schema.statics.listAllQuizes = function listAllQuizes(cb) {
  Model.find({}, cb);
};

Here's an example on how to use it:

var quiz = App.model('quiz');

function home(req, res) { 
  quiz.listAllQuizes(function(err, quizes) {
    if (err) return res.sendStatus(500);
    for (var i = 0; i < quizes.length; i++) {
      console.log(quizes[i].quizName)
    }
    res.render('quiz', { quizList : quizes });
  });
}

edited Feb 06 '16 at 06:59

answered Feb 06 '16 at 06:52

robertklep

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@kumarD can you show us how you are using `listAllQuizes`? – robertklep Feb 06 '16 at 06:55
var quiz = App.model('quiz'); function home(req,res){ quizes = quiz.listAllQuizes(); for(var i=0;i – kumarD Feb 06 '16 at 06:56
@kumarD I added an update to my answer to show how to use it. – robertklep Feb 06 '16 at 07:00
sir, that code above is how i was using it , without passing a callback function to listAllQuizes(); now i changed it to have a callback function as parameter, and it works, thanks a lot :) – kumarD Feb 06 '16 at 07:05
you are awesome, thanks for sharing the example sir :) – kumarD Feb 06 '16 at 07:06

score 2 · Answer 2 · answered Feb 06 '16 at 06:54

2

Assuming you have code somewhere that looks like this:

foo.listAllQuizzes(function (err, quizzes) {
  ...
});

Then your function listAllQuizzes is passed a callback:

schema.statics.listAllQuizzes = function (cb) {
  Model.find({}, function(err, quizzes) {
    if (err) return cb(err);
    cb(null, quizzes);
  });
};

answered Feb 06 '16 at 06:54

Wex

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10
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Sure, but I think robertklep's answer is probably more of the complete solution you're looking for – Wex Feb 06 '16 at 07:04

Callback is not a function in mongoose.find({})

2 Answers2