Query Feature Class

The following example demonstrates how to query features from a Feature Class by one spatial query condition and one attribtue query condition. The spatial query condition selects only features where the geometry intersects the specified polygon. The attribute query condition selects only features where the name attributes equals "Austria".

HTTP REST APISDK

POST /api/gis/dataset/{id}/query
[ body ]
{
"conditions": [
    {
        "geometry": {"type": "Polygon", "coordinates": [...]}
        "operator": "Intersects"
    },
    {
        "name": "name"
        "operator": "Equal"
        "value": "Austria"
    }
]
}

IGISClient _gisClient ;// see SDK how to get the client
var projectId = Guid.NewGuid(); // define relevant project id

var queryGeometryWkt = "POLYGON((7.59 53.21,23.76 53.21,23.76 44.70,7.59 44.70,7.59 53.21))";
var wktReader = new WKTReader();
var queryGeometry = wktReader.Read(queryGeometryWkt);

var conditions = new QueryCondition[] {
    new AttributeQueryCondition { Name="name", Operator = AttributeOperator.Equal, Value = "Austria" },
    new SpatialQueryCondition { Geometry = queryGeometry, Operator = SpatialOperator.Intersects }
};

var fc = await _gisClient.QueryFeatureClassAsync(_fixture.ProjectId, datasetId, conditions);

var attributes = fc.Attributes;
var features = fc.Features;
var firstFeature = features.First();
var firstGeometry = firstFeature.Geometry;
var firstAttributes = firstFeature.Attributes;

The SDK offers several spatial filters. The Intersection is demenstrated above, another available spatial query conditon is WithIn operatior. The example below shows how to limit query result to nearest 5 features to the given geometry.

HTTP REST APISDK

POST /api/gis/dataset/{id}/query
[ body ]
{
    "limitClause":
    {
        "type": "LimitToNearest",
        "geometry": {"type": "Point", "coordinates": [14.22056, 50.76978]},
        "limit":1
    }
}

IGISClient _gisClient ;// see SDK how to get the client
var projectId = Guid.NewGuid(); // define relevant project id

var queryGeometryWkt = "POINT(14.22056, 50.76978)";
var wktReader = new WKTReader();
var queryGeometry = wktReader.Read(queryGeometryWkt);

var limit = new LimitToNearest() {
    Limit = 5,
    Geometry = queryGeometry
};

var fc = await _gisClient.QueryFeatureClassAsync(_fixture.ProjectId, datasetId, limitClause: limit);

var attributes = fc.Attributes;
var features = fc.Features;
var firstFeature = features.First();
var firstGeometry = firstFeature.Geometry;
var firstAttributes = firstFeature.Attributes;