Spatial Query

Question

dear

i'm developing gis xamarin app

how i can make spatial query

i select 1 region from first layer

and i want to select all cities within selected resgion

i pass geometry of selected feature to the query but it not work

any help plz

mohammedalsaleh · Answer

Thank you very much Nagma

its worked with me

but i have problem

by rendering graphics the result is 100% true

but when i make add watch and i tracing the (citiesWithinState) parameter it not have just features withen first result geometry

it have all cities in the gdb (because i want to binding cities name also how i can get it)

NagmaYasmin · Answer

Hi Mohammed,

Using GeometryEngine.Intersection() method, I was able to select the cities with a state. Below is the code, since it has the XAML part for the Graphics Overlay, I have attached the project, the project is in WPF..

// City Layer
 FeatureLayer cityLayer = new FeatureLayer(new Uri("http://sampleserver6.arcgisonline.com/arcgis/rest/services/USA/MapServer/0"));

// State Layer
 FeatureLayer stateLayer = new FeatureLayer(new Uri("http://sampleserver6.arcgisonline.com/arcgis/rest/services/USA/MapServer/2"));

MyMap.OperationalLayers.Add(cityLayer);
 MyMap.OperationalLayers.Add(stateLayer);

// State Query
 QueryParameters stateQueryParameters = new QueryParameters();

// only select one polygon from State layer
 stateQueryParameters.WhereClause = "state_name = 'California'";

// Query the State feature table 
 FeatureQueryResult stateQueryResult = await stateLayer.FeatureTable.QueryFeaturesAsync(stateQueryParameters);
 var stateResult = stateQueryResult.ToList();

// City Query
 QueryParameters cityQueryParameter = new QueryParameters();
 cityQueryParameter.WhereClause = "1=1";

// Query the City feature table 
 FeatureQueryResult cityQueryResult = await cityLayer.FeatureTable.QueryFeaturesAsync(cityQueryParameter);
 var cities = cityQueryResult.Select(feature => feature.Geometry);

var citiesWithinState = cities
 .Select(city => GeometryEngine.Intersection(city, stateResult[0].Geometry))
 .Select(city => new Graphic(city, _markerSymbol));

foreach (Graphic g in citiesWithinState)
 {
 _pointFeatureOverlay.Graphics.Add(g);
 }

}

Hope that helps.

Nagma

SpatialFilter.zip