Question

I work a lot with MongoDb Geospatial indexing, and now I am in the process of replacing the old NoRM framework with the official 10gen C Sharp driver. The problem I am having is that for the existing data that was handled by NoRM, coordinates were in the opposite order [y,x] and it seems like the official driver doesn’t like it.

So I for the existing data I have this structure:

{
   "Coordinates" [: 
   {
      "Longitude" : -85.68216, 
      "Latitude" : 38.221452          
   },
   //.. more coordinates
   ]
}

So my question is, how can I modify the order of all the elements within the array so it they look like:

{
   "Coordinates" [: 
   {
      "Latitude" : 38.221452,  
      "Longitude" : -85.68216               
   },
   //.. more coordinates
   ]
}

Thanks!

Answer 1

If you want to reverse the order, you’ll need to go through the entire collection and rewrite each document in the correct format. Here’s some JavaScript code to do that: feel free to season to taste.

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

do {
    var doc = iter.next();
    var newdoc = {};
    newdoc.Coordinates = [];
    for ( var k in doc.Coordinates ) {
        var newpair = { Latitude: doc.Coordinates[k].Latitude, 
                        Longitude: doc.Coordinates[k].Longitude } ;
        newdoc.Coordinates.push(newpair);
    }
    XDB.update({_id: doc._id}, newdoc );
} while ( iter.hasNext() );