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ArcGIS Runtime SDK for .NET

List related features

This code sample is available for these platforms:
View Sample on GitHub

List features related to the selected feature.

Image of list related features

Use case

Related features are useful for managing relational information, like what you would store in a relational database management system (RDBMS). You can define relationship between records as one-to-one, one-to-many, or many-to-one. For example, you could model inspections and facilities as a many-to-one relationship. Then, for any facility feature, you could list related inspection features.

How to use the sample

Click on a feature to select it. The related features will be displayed in a list.

How it works

  1. With a Feature, call QueryRelatedFeaturesAsync on the feature's feature table.
  2. Iterate over the result's collection of RelatedFeatureQueryResult objects to get the related features and add them to a list.

Relevant API

  • ArcGISFeature
  • ArcGISFeatureTable
  • FeatureQueryResult
  • FeatureTable.QueryRelatedFeatures
  • RelatedFeatureQueryResult

Tags

features, identify, query, related, relationship, search

Sample Code

<UserControl
    x:Class="ArcGISRuntime.UWP.Samples.ListRelatedFeatures.ListRelatedFeatures"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:esriUI="using:Esri.ArcGISRuntime.UI.Controls">
    <Grid>
        <esriUI:MapView x:Name="MyMapView" />
        <Border Style="{StaticResource BorderStyle}">
            <StackPanel>
                <TextBlock Text="Tap a park (green) to see related features."
                           TextAlignment="Center" FontWeight="SemiBold"
                           Margin="0,0,0,10" />
                <ProgressBar x:Name="LoadingProgress"
                             IsIndeterminate="True"
                             Height="15"
                             Margin="0,0,0,10" Visibility="Visible" />
                <ListView x:Name="MyResultsView"
                          MaxHeight="300"
                          ScrollViewer.HorizontalScrollBarVisibility="Disabled"
                          SelectionMode="None">
                    <ListView.ItemTemplate>
                        <DataTemplate>
                            <TextBlock Text="{Binding}" TextWrapping="Wrap" />
                        </DataTemplate>
                    </ListView.ItemTemplate>
                </ListView>
            </StackPanel>
        </Border>
    </Grid>
</UserControl>
// 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: http://www.apache.org/licenses/LICENSE-2.0
//
// 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 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;
using System.Drawing;
using Windows.UI.Popups;
using Windows.UI.Xaml;

namespace ArcGISRuntime.UWP.Samples.ListRelatedFeatures
{
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "List related features",
        category: "Data",
        description: "List features related to the selected feature.",
        instructions: "Click on a feature to select it. The related features will be displayed in a list.",
        tags: new[] { "features", "identify", "query", "related", "relationship", "search" })]
    public partial class ListRelatedFeatures
    {
        // URL to the web map
        private readonly Uri _mapUri =
            new Uri("https://arcgisruntime.maps.arcgis.com/home/item.html?id=dcc7466a91294c0ab8f7a094430ab437");

        // Reference to the feature layer
        private FeatureLayer _myFeatureLayer;

        public ListRelatedFeatures()
        {
            InitializeComponent();

            // Setup the control references and execute initialization
            Initialize();
        }

        private async void Initialize()
        {
            try
            {
                // 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();

                // Wait for the layer to load.
                await _myFeatureLayer.LoadAsync();

                // Update the selection color.
                MyMapView.SelectionProperties.Color = Color.Yellow;

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

                // Hide the loading indicator.
                LoadingProgress.Visibility = Visibility.Collapsed;
            }
            catch (Exception e)
            {
                await new MessageDialog(e.ToString(), "Error").ShowAsync();
            }
        }

        private async void MyMapViewOnGeoViewTapped(object sender, GeoViewInputEventArgs e)
        {
            try
            {
                // Clear any existing feature selection and results list.
                _myFeatureLayer.ClearSelection();
                MyResultsView.ItemsSource = 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;
                }

                // Show the loading indicator (this can take a while).
                LoadingProgress.Visibility = Visibility.Visible;

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

                // Select the feature.
                _myFeatureLayer.SelectFeature(myFeature);

                // 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 = $"{tableName} - {featureDisplayname}";

                        // Add the result to the list.
                        queryResultsForUi.Add(formattedResult);
                    }
                }

                // Update the UI with the result list.
                MyResultsView.ItemsSource = queryResultsForUi;

                // Hide the loading indicator.
                LoadingProgress.Visibility = Visibility.Collapsed;
            }
            catch (Exception ex)
            {
                await new MessageDialog(ex.ToString(), "Error").ShowAsync();
            }
        }
    }
}