Geospatial queries in MongoDB - Part 2 : {"err": "location object expected, location array not in correct format" "code": 16804}

In my last post we saw we had to create a geospatial index on the "pos" field as follows:

> db.foodtrucks.ensureIndex({pos:"2d"})

However, when executing the command above we get the following error:

 > db.foodtrucks.ensureIndex({pos:"2d"})
{
    "createdCollectionAutomatically" : false,
    "numIndexesBefore" : 3,
    "ok" : 0,
    "errmsg" : "location object expected, location array not in correct format",
    "code" : 16804
}

After some further investigation I realized that we had some documents which didn't had any latitude/longitude information. Due to this some of the documents looked like this:

{
   "_id":ObjectId("53d07bf1e3e11dacc21056a8"),
   "locationid":437222,
   "Applicant":"Natan's Catering",
   "FacilityType":"Truck",
   "cnn":188101,
   "LocationDescription":"03RD ST: 18TH ST to 19TH ST (2101 - 2199) -- EAST --",
   "Address":"2101 03RD ST",
   "blocklot":4045004,
   "block":4045,
   "lot":4,
   "permit":"13MFF-0102",
   "Status":"EXPIRED",
   "FoodItems":"Burgers: melts: hot dogs: burritos:sandwiches: fries: onion rings: drinks",
   "X":"",
   "Y":"",
   "Latitude":"",
   "Longitude":"",
   "Schedule":"http://bsm.sfdpw.org/PermitsTracker/reports/report.aspx?title=schedule&report=rptSchedule&params=permit=13MFF-0102&ExportPDF=1&Filename=13MFF-0102_schedule.pdf",
   "NOISent":"",
   "Approved":"04/12/2013 02:43:48 PM",
   "Received":"Apr 12 2013  2:33PM",
   "PriorPermit":1,
   "ExpirationDate":"03/15/2014 12:00:00 AM",
   "Location":"",
   "pos":{
      "Longitude":"",
      "Latitude":""
   }
}

As we can see the "pos" entry above(in red) is empty. To address this issue, I made some changes to my JavaScript module to do null checks. Here is the updated code:

XDB = db.foodtrucks;
var iter = XDB.find()

do {
    var doc = iter.next();
    var newdoc = {};
    newdoc.pos = [];
    if(!doc.Longitude && !doc.Latitude){ // if the values are null, skip adding this entry

   }else{ // else add it
        var newpair =  {Longitude: doc.Longitude,Latitude: doc.Latitude} ;
        newdoc.pos.push(newpair);
    XDB.update({_id: doc._id},{$set:{pos: newpair}});
   }
} while ( iter.hasNext() );

Once we execute this, all the document in the collection will only have this entry if the values are not null. If we try to create a geospatial index now, it goes through successfully: 

 db.foodtrucks.ensureIndex({pos:"2d"})
{
    "createdCollectionAutomatically" : false,
    "numIndexesBefore" : 3,
    "numIndexesAfter" : 4,
    "ok" : 1
}