List related features

This sample demonstrates how to query features related to an identified feature.

List related features


Click on a feature to identify it. Related features will be listed in the window above the map.


// Copyright 2018 Esri.
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
// You may obtain a copy of the License at:
// Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific
// language governing permissions and limitations under the License.

using Android.App;
using Android.OS;
using Android.Widget;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Portal;
using Esri.ArcGISRuntime.UI.Controls;
using System;
using System.Collections.Generic;
using System.Linq;

namespace ArcGISRuntimeXamarin.Samples.ListRelatedFeatures
    public class ListRelatedFeatures : Activity
        // URL to the web map
        private readonly Uri _mapUri =
            new Uri("");

        // Reference to the feature layer
        private FeatureLayer _myFeatureLayer;

        // Create and hold reference to the used MapView
        private MapView _myMapView = new MapView();

        // Hold a reference to the ListView
        private ListView _myDisplayList;

        protected override void OnCreate(Bundle bundle)

            Title = "List related features";

            // Create the UI, setup the control references and execute initialization

        private async void Initialize()
            // Create the portal item from the URL to the webmap
            PortalItem alaskaPortalItem = await PortalItem.CreateAsync(_mapUri);

            // Create the map from the portal item
            Map myMap = new Map(alaskaPortalItem);

            // Add the map to the mapview
            _myMapView.Map = myMap;

            // Wait for the map to load
            await myMap.LoadAsync();

            // Get the feature layer from the map
            _myFeatureLayer = (FeatureLayer)myMap.OperationalLayers.First();

            // Make the selection color yellow and the width thick
            _myFeatureLayer.SelectionColor = System.Drawing.Color.Yellow;
            _myFeatureLayer.SelectionWidth = 5;

            // Listen for GeoViewTapped events
            _myMapView.GeoViewTapped += MyMapViewOnGeoViewTapped;

        private async void MyMapViewOnGeoViewTapped(object sender, GeoViewInputEventArgs e)
            // Clear any existing feature selection and results list
            _myDisplayList.Adapter = null;

            // Identify the tapped feature
            IdentifyLayerResult results = await _myMapView.IdentifyLayerAsync(_myFeatureLayer, e.Position, 10, false);

            // Return if there are no results
            if (results.GeoElements.Count < 1) { return; }

            // Get the first result
            ArcGISFeature myFeature = (ArcGISFeature)results.GeoElements.First();

            // Select the feature

            // Get the feature table for the feature
            ArcGISFeatureTable myFeatureTable = (ArcGISFeatureTable)myFeature.FeatureTable;

            // Query related features
            IReadOnlyList<RelatedFeatureQueryResult> relatedFeaturesResult = await myFeatureTable.QueryRelatedFeaturesAsync(myFeature);

            // Create a list to hold the formatted results of the query
            List<String> queryResultsForUi = new List<string>();

            // For each query result
            foreach (RelatedFeatureQueryResult result in relatedFeaturesResult)
                // And then for each feature in the result
                foreach (Feature resultFeature in result)
                    // Get a reference to the feature's table
                    ArcGISFeatureTable relatedTable = (ArcGISFeatureTable)resultFeature.FeatureTable;

                    // Get the display field name - this is the name of the field that is intended for display
                    string displayFieldName = relatedTable.LayerInfo.DisplayFieldName;

                    // Get the name of the feature's table
                    string tableName = relatedTable.TableName;

                    // Get the display name for the feature
                    string featureDisplayname = resultFeature.Attributes[displayFieldName].ToString();

                    // Create a formatted result string
                    string formattedResult = String.Format("{0} - {1}", tableName, featureDisplayname);

                    // Add the result to the list

            // Create an array adapter for the layer display
            ArrayAdapter adapter = new ArrayAdapter(this, Android.Resource.Layout.SimpleSpinnerItem, queryResultsForUi);

            // Apply the adapter to show the results in the UI
            _myDisplayList.Adapter = adapter;

        private void CreateLayout()
            // Create a new vertical layout for the app
            var layout = new LinearLayout(this) { Orientation = Orientation.Vertical };

            // Create the listview for displaying results
            _myDisplayList = new ListView(this);

            // Create a scrollviewer for the listview
            ScrollView myScrollView = new ScrollView(this);

            // Set the height so that it always appears on screen
            myScrollView.SetMinimumHeight(Resources.DisplayMetrics.HeightPixels / 3);
            myScrollView.FillViewport = true;

            // Add the listview to the scroll view

            // Add the scroll view to the layout

            // Add the map view to the layout

            // Show the layout in the app

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