MongoDb C# GeoNear Query Construction

Found the answer via this and this:

var earthRadius = 6378.0; // kmvar rangeInKm = 3000.0; // kmmyCollection.EnsureIndex(IndexKeys.GeoSpatial("Location"));var near =    Query.GT("ExpiresOn", now);var options = GeoNearOptions    .SetMaxDistance(rangeInKm / earthRadius /* to radians */)    .SetSpherical(true);var results = myCollection.GeoNear(    near,    request.Longitude, // note the order    request.Latitude,  // [lng, lat]    200,    options);

Here is a working example for driver v2.10+. It uses a correct geospatial point field type and runs $nearSphere query.

var longitude = 30d; //xvar latitude= 50d; //yvar point = new GeoJsonPoint<GeoJson2DGeographicCoordinates>(new GeoJson2DGeographicCoordinates(longitude, latitude));var filter = Builders<TDocument>.Filter.NearSphere(doc => doc.YourLocationField, point, maxGeoDistanceInKm * 1000);var result = await collection.Find(filter).ToListAsync();

Type of YourLocationField should be GeoJsonPoint<GeoJson2DGeographicCoordinates>.

PS. Also you can create an index of your field for faster searching like this:

collection.Indexes.CreateManyAsync(    new []    {        new CreateIndexModel<TDocument>(Builders<TDocument>.IndexKeys.Geo2DSphere(it => it.YourLocationField))    });

there is no GeoNear method on IMongoCollection anymore in the 2.x driver.here's a strongly typed and easy way to do $geoNear queries using MongoDB.Entities convenience library.

using MongoDB.Driver;using MongoDB.Entities;namespace StackOverflow{    public class Program    {        public class Cafe : Entity        {            public string Name { get; set; }            public Coordinates2D Location { get; set; }            public double DistanceMeters { get; set; }        }        private static void Main(string[] args)        {            new DB("test");            DB.Index<Cafe>()              .Key(c => c.Location, KeyType.Geo2DSphere)              .Create();            (new Cafe            {                Name = "Coffee Bean",                Location = new Coordinates2D(48.8539241, 2.2913515),            }).Save();            var searchPoint = new Coordinates2D(48.796964, 2.137456);            var cafes = DB.GeoNear<Cafe>(                               NearCoordinates: searchPoint,                               DistanceField: c => c.DistanceMeters,                               MaxDistance: 20000)                          .ToList();        }    }}

the above code sends the following query to mongodb server:

db.Cafe.aggregate([    {        "$geoNear": {            "near": {                "type": "Point",                "coordinates": [                    48.796964,                    2.137456                ]            },            "distanceField": "DistanceMeters",            "spherical": true,            "maxDistance": NumberInt("20000")        }    }])