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Microsoft added geospatial support, which lets you store location data in your documents and perform spatial calculations for distance and intersections between points and polygons.
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Spatial data describes the position and shape of objects in space.
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Typically, it can be used to represent the location of a person, a place of interest, or the boundary of a city, or a lake.
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Common use cases often involve proximity queries. For e.g., “find all universities near my current location”.
A Point denotes a single position in space which represents the exact location, e.g. street address of particular university. A point is represented in DocumentDB using its coordinate pair (longitude and latitude). Following is an example of JSON point.
{ "type":"Point", "coordinates":[ 28.3, -10.7 ] }
Let’s take a look at a simple example which contains the location of a university.
{ "id":"case-university", "name":"CASE: Center For Advanced Studies In Engineering", "city":"Islamabad", "location": { "type":"Point", "coordinates":[ 33.7194136, -73.0964862 ] } }
To retrieve the university name based on the location, you can use the following query.
SELECT c.name FROM c WHERE c.id = "case-university" AND ST_ISVALID({ "type":"Point", "coordinates":[ 33.7194136, -73.0964862 ] })
When the above query is executed you will receive the following output.
[ { "name": "CASE: Center For Advanced Studies In Engineering" } ]
Create Document with Geospatial Data in .NET
You can create a document with geospatial data, let’s take a look at a simple example in which a university document is created.
private async static Task CreateDocuments(DocumentClient client) { Console.WriteLine(); Console.WriteLine("**** Create Documents ****"); Console.WriteLine(); var uniDocument = new UniversityProfile { Id = "nust", Name = "National University of Sciences and Technology", City = "Islamabad", Loc = new Point(33.6455715, 72.9903447) }; Document document = await CreateDocument(client, uniDocument); Console.WriteLine("Created document {0} from typed object", document.Id); Console.WriteLine(); }
Following is the implementation for the UniversityProfile class.
public class UniversityProfile { [JsonProperty(PropertyName = "id")] public string Id { get; set; } [JsonProperty("name")] public string Name { get; set; } [JsonProperty("city")] public string City { get; set; } [JsonProperty("location")] public Point Loc { get; set; } }
When the above code is compiled and executed, you will receive the following output.
**** Create Documents **** Created new document: nust { "id": "nust", "name": "National University of Sciences and Technology", "city": "Islamabad", "location": { "type": "Point", "coordinates": [ 33.6455715, 72.9903447 ] }, "_rid": "Ic8LAMEUVgANAAAAAAAAAA==", "_ts": 1450200910, "_self": "dbs/Ic8LAA==/colls/Ic8LAMEUVgA=/docs/Ic8LAMEUVgANAAAAAAAAAA==/", "_etag": ""00004100-0000-0000-0000-56704f4e0000"", "_attachments": "attachments/" } Created document nust from typed object
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