Method GetGeoJSON

Namespace

YndigoBlue.Velocity.Engine

Assembly

YndigoBlue.Velocity.dll

GetGeoJSON(string, string)

Converts query results containing geospatial data to GeoJSON format.

public string GetGeoJSON(string geospatialColumnName, string idPropertyName = "id")

Parameters

geospatialColumnName string

The name of the column containing geometry or geography data.

idPropertyName string

The attribute name promoted from GeoJSON "properties" to the Feature's top-level "id" member (the idiomatic GeoJSON convention for a row's identifier, recognized by tools such as Mapbox GL and Leaflet). Pass null or an empty string to disable promotion and leave it as a regular property.

Returns

string

A GeoJSON FeatureCollection string containing all results.

Examples

var conn = new PostgreSqlDatasourceConnection
{
    Hostname = "localhost",
    Database = "gis_data",
    Username = "user",
    Password = "password"
};

using (var manager = new Manager(conn))
{
    var schema = manager.LoadSchema("public");
    var citiesTable = schema["cities"];

    var query = new Query()
        .Select([citiesTable["id"], citiesTable["name"], citiesTable["population"], citiesTable["location"]])
        .From(citiesTable);

    using (ResultSet results = manager.Retrieve(query))
    {
        // Export to GeoJSON for mapping applications — the "id" column is promoted to
        // each Feature's top-level "id"
        string geoJson = results.GetGeoJSON("location");
        File.WriteAllText("cities.geojson", geoJson);
    }
}

Remarks

Warning

GeoJSON export for geospatial data is not available in the Community Edition of Velocity. It requires the Full Edition.