MapImageLayerTables.xaml.cs

// Copyright 2022 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.ArcGISServices;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;

using Color = System.Drawing.Color;

namespace ArcGIS.Samples.MapImageLayerTables
{
    [ArcGIS.Samples.Shared.Attributes.Sample(
        name: "Map image layer tables",
        category: "Layers",
        description: "Find features in a spatial table related to features in a non-spatial table.",
        instructions: "Once the map image layer loads, a list view will be populated with comment data from non-spatial features. Tap on one of the comments to query related spatial features and display the first result on the map.",
        tags: new[] { "features", "query", "related features", "search" })]
    public partial class MapImageLayerTables : ContentPage
    {
        // A graphics overlay for showing selected features.
        private GraphicsOverlay _selectedFeaturesOverlay;

        public MapImageLayerTables()
        {
            InitializeComponent();

            // Initialize the map and show the list of comments.
            _ = Initialize();
        }

        private async Task Initialize()
        {
            try
            {
                // Create a new Map with a streets basemap.
                Map myMap = new Map(BasemapStyle.ArcGISStreets);

                // Create the URI to the Service Requests map service.
                Uri serviceRequestUri = new Uri("https://sampleserver6.arcgisonline.com/arcgis/rest/services/ServiceRequest/MapServer");

                // Create a new ArcGISMapImageLayer that uses the service URI.
                ArcGISMapImageLayer serviceRequestsMapImageLayer = new ArcGISMapImageLayer(serviceRequestUri);

                // Load all sublayers and tables contained by the map image layer.
                await serviceRequestsMapImageLayer.LoadTablesAndLayersAsync();

                // Set the initial map extent to the extent of all service request features.
                Envelope requestsExtent = serviceRequestsMapImageLayer.FullExtent;
                myMap.InitialViewpoint = new Viewpoint(requestsExtent);

                // Add the layer to the map.
                myMap.OperationalLayers.Add(serviceRequestsMapImageLayer);

                // Get the service request comments table from the map image layer.
                ServiceFeatureTable commentsTable = serviceRequestsMapImageLayer.Tables[0];

                // Create query parameters to get all non-null service request comment records (features) from the table.
                QueryParameters queryToGetNonNullComments = new QueryParameters
                {
                    WhereClause = "requestid <> '' AND comments <> ''"
                };

                // Query the comments table to get the non-null records.
                FeatureQueryResult commentQueryResult = await commentsTable.QueryFeaturesAsync(queryToGetNonNullComments, QueryFeatureFields.LoadAll);

                // Show the records from the service request comments table in the list view control.
                CommentsListBox.ItemsSource = commentQueryResult.ToList();

                // Create a graphics overlay to show selected features and add it to the map view.
                _selectedFeaturesOverlay = new GraphicsOverlay();
                MyMapView.GraphicsOverlays.Add(_selectedFeaturesOverlay);

                // Assign the map to the MapView.
                MyMapView.Map = myMap;
            }
            catch (Exception e)
            {
                await Application.Current.MainPage.DisplayAlert("Error", e.ToString(), "OK");
            }
        }

        // Handle a new selected comment record in the table view.
        private async void CommentsListBox_SelectionChanged(object sender, SelectedItemChangedEventArgs e)
        {
            // Clear selected features from the graphics overlay.
            _selectedFeaturesOverlay.Graphics.Clear();

            // Get the selected comment feature. If there is no selection, return.
            ArcGISFeature selectedComment = e.SelectedItem as ArcGISFeature;
            if (selectedComment == null) { return; }

            // Get the map image layer that contains the service request sublayer and the service request comments table.
            ArcGISMapImageLayer serviceRequestsMapImageLayer = (ArcGISMapImageLayer)MyMapView.Map.OperationalLayers[0];

            // Get the (non-spatial) table that contains the service request comments.
            ServiceFeatureTable commentsTable = serviceRequestsMapImageLayer.Tables[0];

            // Get the relationship that defines related service request features for features in the comments table (this is the first and only relationship).
            RelationshipInfo commentsRelationshipInfo = commentsTable.LayerInfo.RelationshipInfos.FirstOrDefault();

            // Create query parameters to get the related service request for features in the comments table.
            RelatedQueryParameters relatedQueryParams = new RelatedQueryParameters(commentsRelationshipInfo)
            {
                ReturnGeometry = true
            };

            try
            {
                // Query the comments table to get the related service request feature for the selected comment.
                IReadOnlyList<RelatedFeatureQueryResult> relatedRequestsResult = await commentsTable.QueryRelatedFeaturesAsync(selectedComment, relatedQueryParams);

                // Get the first result.
                RelatedFeatureQueryResult result = relatedRequestsResult.FirstOrDefault();

                // Get the first feature from the result. If it's null, warn the user and return.
                ArcGISFeature serviceRequestFeature = result.FirstOrDefault() as ArcGISFeature;
                if (serviceRequestFeature == null)
                {
                    await Application.Current.MainPage.DisplayAlert("No Feature", "Related feature not found.", "OK");
                    return;
                }

                // Load the related service request feature (so its geometry is available).
                await serviceRequestFeature.LoadAsync();

                // Get the service request geometry (point).
                MapPoint serviceRequestPoint = serviceRequestFeature.Geometry as MapPoint;

                // Create a cyan marker symbol to display the related feature.
                Symbol selectedRequestSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle.Circle, Color.Cyan, 14);

                // Create a graphic using the service request point and marker symbol.
                Graphic requestGraphic = new Graphic(serviceRequestPoint, selectedRequestSymbol);

                // Add the graphic to the graphics overlay and zoom the map view to its extent.
                _selectedFeaturesOverlay.Graphics.Add(requestGraphic);
                await MyMapView.SetViewpointCenterAsync(serviceRequestPoint, 150000);
            }
            catch (Exception ex)
            {
                await Application.Current.MainPage.DisplayAlert("Error", ex.ToString(), "OK");
            }
        }
    }
}