Update geometries (feature service)

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Update a feature's location in an online feature service.

Image of update geometries feature service

Use case

Sometimes users may want to edit features in an online feature service by moving them.

How to use the sample

Tap a feature to select it. Tap again to set the updated location for that feature. An alert will be shown confirming success or failure.

How it works

  1. Create a ServiceFeatureTable object from a URL.
  2. Create a FeatureLayer object from the ServiceFeatureTable.
  3. Select a feature from the feature layer, using FeatureLayer.SelectFeatures.
  4. Load the selected feature.
  5. Change the selected feature's location using Feature.Geometry = geometry.
  6. After the change, update the table on the server using ApplyEditsAsync.

Relevant API

  • Feature
  • FeatureLayer
  • ServiceFeatureTable

Tags

editing, feature layer, feature table, moving, service, updating

Sample Code

UpdateGeometries.cs
                                                                                                                                                                                      
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// Copyright 2019 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 Android.App;
using Android.OS;
using Android.Widget;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.UI.Controls;
using System;
using System.Linq;
using Android.Views;

namespace ArcGISRuntimeXamarin.Samples.UpdateGeometries
{
    [Activity (ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Update geometries (feature service)",
        category: "Data",
        description: "Update a feature's location in an online feature service.",
        instructions: "Tap a feature to select it. Tap again to set the updated location for that feature. An alert will be shown confirming success or failure.",
        tags: new[] { "editing", "feature layer", "feature table", "moving", "service", "updating" })]
    public class UpdateGeometries : Activity
    {
        // Hold a reference to the MapView.
        private MapView _myMapView;

        // URL to the feature service.
        private const string FeatureServiceUrl = "https://sampleserver6.arcgisonline.com/arcgis/rest/services/DamageAssessment/FeatureServer/0";

        // Hold a reference to the feature layer.
        private FeatureLayer _damageLayer;

        // Hold a reference to the selected feature.
        private ArcGISFeature _selectedFeature;

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            Title = "Update geometries (feature service)";

            CreateLayout();
            Initialize();
        }

        private void Initialize()
        {
            // Create the map with streets basemap.
            _myMapView.Map = new Map(BasemapStyle.ArcGISStreets);

            // Create the feature table, referring to the Damage Assessment feature service.
            ServiceFeatureTable damageTable = new ServiceFeatureTable(new Uri(FeatureServiceUrl));

            // Create a feature layer to visualize the features in the table.
            _damageLayer = new FeatureLayer(damageTable);

            // Add the layer to the map.
            _myMapView.Map.OperationalLayers.Add(_damageLayer);

            // Listen for user taps on the map - on tap, a feature will be selected.
            _myMapView.GeoViewTapped += MapView_Tapped;

            // Zoom to the United States.
            _myMapView.SetViewpointCenterAsync(new MapPoint(-10800000, 4500000, SpatialReferences.WebMercator), 3e7);
        }

        private void MapView_Tapped(object sender, GeoViewInputEventArgs e)
        {
            // Select the feature if none selected, move the feature otherwise.
            if (_selectedFeature == null)
            {
                // Select the feature.
                TrySelectFeature(e);
            }
            else
            {
                // Move the feature.
                MoveSelectedFeature(e);
            }
        }

        private async void MoveSelectedFeature(GeoViewInputEventArgs tapEventDetails)
        {
            try
            {
                // Get the MapPoint from the EventArgs for the tap.
                MapPoint destinationPoint = tapEventDetails.Location;

                // Normalize the point - needed when the tapped location is over the international date line.
                destinationPoint = (MapPoint) GeometryEngine.NormalizeCentralMeridian(destinationPoint);

                // Load the feature.
                await _selectedFeature.LoadAsync();

                // Update the geometry of the selected feature.
                _selectedFeature.Geometry = destinationPoint;

                // Apply the edit to the feature table.
                await _selectedFeature.FeatureTable.UpdateFeatureAsync(_selectedFeature);

                // Push the update to the service.
                ServiceFeatureTable serviceTable = (ServiceFeatureTable) _selectedFeature.FeatureTable;
                await serviceTable.ApplyEditsAsync();
                ShowMessage("Success!", $"Moved feature {_selectedFeature.Attributes["objectid"]}");
            }
            catch (Exception ex)
            {
                ShowMessage("Error when moving feature", ex.ToString());
            }
            finally
            {
                // Reset the selection.
                _damageLayer.ClearSelection();
                _selectedFeature = null;
            }
        }

        private async void TrySelectFeature(GeoViewInputEventArgs tapEventDetails)
        {
            try
            {
                // Perform an identify to determine if a user tapped on a feature.
                IdentifyLayerResult identifyResult = await _myMapView.IdentifyLayerAsync(_damageLayer, tapEventDetails.Position, 10, false);

                // Do nothing if there are no results.
                if (!identifyResult.GeoElements.Any())
                {
                    return;
                }

                // Get the tapped feature.
                _selectedFeature = (ArcGISFeature)identifyResult.GeoElements.First();

                // Select the feature.
                _damageLayer.SelectFeature(_selectedFeature);
            }
            catch (Exception ex)
            {
                ShowMessage("Problem selecting feature", ex.ToString());
            }
        }

        private void ShowMessage(string title, string message)
        {
            // Display the message to the user.
            AlertDialog.Builder builder = new AlertDialog.Builder(this);
            builder.SetMessage(message).SetTitle(title).Show();
        }

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

            // Create the help label.
            TextView helpLabel = new TextView(this);
            helpLabel.Text = "Tap to select a feature. Tap again to move it.";
            helpLabel.TextAlignment = TextAlignment.Center;
            helpLabel.Gravity = GravityFlags.Center;

            // Add the help label to the layout.
            layout.AddView(helpLabel);

            // Create the map view.
            _myMapView = new MapView(this);

            // Add the map view to the layout.
            layout.AddView(_myMapView);

            // Show the layout in the app.
            SetContentView(layout);
        }
    }
}

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