Fixed async issue

query.js

var DB = require('../../lib/db.js').DB;

function methods() {
  //query object
  var Q = {};
  //will act as our private variables to workaround asynchronous functions.
  //will delete non-required ones when done -- we don't have to, but just for continuity.
  var privates = {};



  //add tag to collection
  Q.add = function(tag) {
    if (typeof tag === "string") {
      //maybe we are adding a tag by name
      var obj = {
        name: tag
      };
    } else if (typeof tag === "object" && tag.name) {
      //maybe the tag object was specified, and tag's name was provided
      var obj = tag;
    }

    require('mongodb').connect(DB.mongo_url, function(err, db) {
      db.collection('tags', function(err, coll) {
        coll.insert(obj, {
          safe: true
        }, function(err, result) {
          //console.log(result);
        });

      });
    });
  }
  var callback = {
    _set: function(key, val) {
      privates[key] = val;
      //console.log(JSON.stringify(privates));
    },
    _get: function(key) {
      //console.log("get: "+privates[key]);
      //console.log(JSON.stringify(privates));
      return privates[key];
    },
    _unset: function(key) {
      //delete privates[key];
    }
  }
  var if_exists = function(query, where, callback) {

    require('mongodb').connect(DB.mongo_url, function(err, db) {
      db.collection(where, function(err, coll) {
        coll.findOne(query, function(e, r) {
          //console.log(r);
          if (r === null) {
            callback(e, false);
            //console.log("set : "+ callback._get("does_exist"));
          } else {
            callback(e, true);
            //console.log("set : "+ callback._get("does_exist"));
          }

        });
      });
      //console.log("final set : "+ callback._get("does_exist"));
    });
    //console.log("last set : "+ callback._get("does_exist"));
    //var result = callback._get("does_exist");
    // delete privates.does_exist;
    //return result;
  }
Q.if_exists = if_exists;
  /*Q.if_exists = function(query, where) {
    var res;
    if_exists(query, where, function(error, result) {
      console.log('the result: '+result);
      res = result;
    });
    console.log('res '+res);
    return res;

  }*/



  return Q;
}


exports.query = methods();

query.test.js

var query = require('./query.js').query;
console.log("running unit tests...");

console.log("add query test");
query.add("os");
query.add({
  name: "rhcp"
});


console.log("exists tests:");
var result = query.if_exists({
  name: "os"
}, "tags", function(error, result) {

console.log("should be true: " + result);
});

var result = query.if_exists({
  name: "ossuruk"
}, "tags", function(error, result) {
  console.log("should be false:" + result)
});