MongoDB Geospatial Queries in C#

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// Point GeoJSON type
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{
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    "type" : "Point",
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    "coordinates" : [-115.20146200000001, 36.114704000000003]
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}
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// Polygon GeoJSON type
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{
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    "type": "Polygon",
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    "coordinates": [
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        [
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            [100.0, 0.0], 
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            [101.0, 0.0], 
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            [101.0, 1.0],
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            [100.0, 1.0], 
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            [100.0, 0.0]
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        ]
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    ]
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}

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{ "location": "2dsphere" }

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{ "geometry": "2dsphere" }

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Install-Package MongoDB.Driver

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dotnet add package MongoDB.Driver

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using MongoDB.Bson;
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using MongoDB.Bson.IO;
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using MongoDB.Bson.Serialization;
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using MongoDB.Driver;
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using MongoDB.Driver.GeoJsonObjectModel;
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using System;

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public class Restaurant
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{
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    public ObjectId Id { get; set; }
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    public GeoJsonPoint<GeoJson2DCoordinates> Location { get; set; }
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    public string Name { get; set; }
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}

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public class Neighborhood
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{
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    public ObjectId Id { get; set; }
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    public GeoJsonPoint<GeoJson2DCoordinates> Geometry { get; set; }
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    public string Name { get; set; }
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}

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// Be sure to update yourUsername, yourPassword, yourClusterName, and yourProjectId to your own! 
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// Similarly, also update "sample-geo", "restaurants", and "neighborhoods" to whatever you've named your database and collections.
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var client = new MongoClient("mongodb+srv://yourUsername:yourPassword@yourClusterName.yourProjectId.mongodb.net/sample-geo?retryWrites=true&w=majority");
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var database = client.GetDatabase("sample-geo");
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var restaurantCollection = database.GetCollection<Restaurant>("restaurants");
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var neighborhoodCollection = database.GetCollection<Neighborhood>("neighborhoods");

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private static void Log(string exampleName, FilterDefinition<Restaurant> filter)
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{
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    var serializerRegistry = BsonSerializer.SerializerRegistry;
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    var documentSerializer = serializerRegistry.GetSerializer<Restaurant>();
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    var rendered = filter.Render(documentSerializer, serializerRegistry);
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    Console.WriteLine($"{exampleName} example:");
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    Console.WriteLine(rendered.ToJson(new JsonWriterSettings { Indent = true }));
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    Console.WriteLine();
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}

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private static void NearExample(IMongoCollection<Restaurant> collection)
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{
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    // Instantiate builder
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    var builder = Builders<Restaurant>.Filter;
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    // Set center point to Magnolia Bakery on Bleecker Street
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    var point = GeoJson.Point(GeoJson.Position(-74.005, 40.7358879));
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    // Create geospatial query that searches for restaurants at most 10,000 meters away,
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    // and at least 2,000 meters away from Magnolia Bakery (AKA, our center point)
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    var filter = builder.Near(x => x.Location, point, maxDistance: 10000, minDistance: 2000);
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    // Log filter we've built to the console using our helper method
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    Log("$near", filter);
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}

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static void Main(string[] args)
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{
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    var client = new MongoClient("mongodb+srv://yourUsername:yourPassword@yourClusterName.yourProjectId.mongodb.net/sample-geo?retryWrites=true&w=majority");
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    var database = client.GetDatabase("sample-geo");
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    var restaurantCollection = database.GetCollection<Restaurant>("restaurants");
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    var neighborhoodCollection = database.GetCollection<Neighborhood>("neighborhoods");
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    NearExample(restaurantCollection);
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    // Add other methods here as you create them
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}

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private static void GeoWithinExample(IMongoCollection<Restaurant> collection)
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{
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    var builder = Builders<Restaurant>.Filter;
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    // Build polygon area to search within.
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    // This must always begin and end with the same coordinate 
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    // to "close" the polygon and fully surround the area.
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    var coordinates = new GeoJson2DCoordinates[]
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    {
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        GeoJson.Position(-74.0011869, 40.752482),
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        GeoJson.Position(-74.007384,  40.743641),
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        GeoJson.Position(-74.001856,  40.725631),
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        GeoJson.Position(-73.978511,  40.726793),
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        GeoJson.Position(-73.974408,  40.755243),
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        GeoJson.Position(-73.981669,  40.766716),
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        GeoJson.Position(-73.998423,  40.763535),
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        GeoJson.Position(-74.0011869, 40.752482),
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    };
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    var polygon = GeoJson.Polygon(coordinates);
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    // Create geospatial query that searches for restaurants that fully fall within the polygon.
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    var filter = builder.GeoWithin(x => x.Location, polygon);
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    // Log the filter we've built to the console using our helper method.
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    Log("$geoWithin", filter);
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}

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private static void GeoIntersectsExample(IMongoCollection<Neighborhood> collection)
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{
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    var builder = Builders<Neighborhood>.Filter;
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    // Set specified point. For example, the location of a user (with granted permission)
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    var point = GeoJson.Point(GeoJson.Position(-73.996284, 40.720083));
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    // Create geospatial query that searches for neighborhoods that intersect with specified point.
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    // In other words, return results where the intersection of a neighborhood and the specified point is non-empty.
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    var filter = builder.GeoIntersects(x => x.Geometry, point);
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    // Log the filter we've built to the console using our helper method.
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    Log("$geoIntersects", filter);
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}

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private static void GeoWithinCenterExample(IMongoCollection<Restaurant> collection)
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{
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    var builder = Builders<Restaurant>.Filter;
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    // Set center point to Brooklyn Bridge
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    var point = GeoJson.Point(GeoJson.Position(-73.99631, 40.705396));
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    // Create geospatial query that searches for restaurants that fall within a radius of 20 (units used by the coordinate system)
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    var filter = builder.GeoWithinCenter(x => x.Location, point.Coordinates.X, point.Coordinates.Y, 20);
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    Log("$geoWithin.$center", filter);
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}

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private static void GeoWithinCenterSphereExample(IMongoCollection<Restaurant> collection)
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{
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    var builder = Builders<Restaurant>.Filter;
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    // Set center point to Apollo Theater in Harlem
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    var point = GeoJson.Point(GeoJson.Position(-73.949995, 40.81009));
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    // Create geospatial query that searches for restaurants that fall within a 3-mile radius of Apollo Theater.
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    // Notice how we pass our 3-mile radius parameter as radians (3 / 3963.2). This ensures accurate calculations with the $centerSphere operator.
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    var filter = builder.GeoWithinCenterSphere(x => x.Location, point.Coordinates.X, point.Coordinates.Y, 3 / 3963.2);
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    // Log the filter we've built to the console using our helper method.
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    Log("$geoWithin.$centerSphere", filter);
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}