Proper usage of a callback handler in Node

Question

I am trying to get data that is being returned in a callback but my callback function (callbackFunc()) is not being executed, probably due to the way I am approaching this.If someone would point me in the right direction I would be grateful.

Thanks

   var url = 'mongodb://localhost:27017/bac';
   var term = 'usa';

   MongoClient.connect(url, function(err, db) {

       assert.equal(null, err);
       findDocument(term.toUpperCase(),'country_code', db, function() {db.close();});

   });



function callbackFunc(data){

  console.log("inside callbackFunc()...");
  console.log(data);

}

var findDocument = function(term, field, db, callbackFunc){
    var collection = db.collection('bac');
    collection.findOne({'country_code' : term}, function(err, document){
         assert.equal(err,null);
         console.log("Found this matching record for "+term);
         console.log(document);
         callbackFunc(document);
    });
}

BlackMamba · Accepted Answer · 2016-10-19 01:23:32Z

1

Let see your code:

findDocument(term.toUpperCase(),'country_code', db, function() {db.close();});

You pass wrong callback function, you pass function() {db.close();}.

i think you want pass:

function callbackFunc(data){

  console.log("inside callbackFunc()...");
  console.log(data);

}

so plese use:

findDocument(term.toUpperCase(),'country_code', db, callbackFunc);

answered Oct 19, 2016 at 1:23

BlackMamba

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Comments

lucas.coelho · Accepted Answer · 2016-10-18 22:18:42Z

1

The callback function been called is not the defined callbackFunc

function callbackFunc(data){ console.log("inside callbackFunc()..."); console.log(data); }

but the

function() {db.close();}

Because you are passing in the function arguments.

answered Oct 18, 2016 at 22:18

lucas.coelho

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