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Update attributes (feature service)

Update feature attributes


// 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:
// 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.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.UI.Controls;
using Foundation;
using System;
using System.Collections.Generic;
using System.Linq;
using UIKit;

namespace ArcGISRuntimeXamarin.Samples.UpdateAttributes
        "Update attributes (feature service)",
        "Update feature attributes in an online feature service.",
    public class UpdateAttributes : UIViewController
        // Hold references to the UI controls.
        private MapView _myMapView;

        // URL to the feature service.
        private const string FeatureServiceUrl = "";

        // Name of the field that will be updated.
        private const string AttributeFieldName = "typdamage";

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

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

        // Hold a reference to the domain.
        private CodedValueDomain _domain;

        public UpdateAttributes()
            Title = "Update attributes (feature service)";

        private void Initialize()
            // Create the map with streets basemap.
            _myMapView.Map = new Map(Basemap.CreateStreets());

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

            // When the table loads, use it to discover the domain of the typdamage field.
            damageTable.Loaded += DamageTable_Loaded;

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

            // Add the layer to the map.

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

        private void DamageTable_Loaded(object sender, EventArgs e)
            // This code needs to work with the UI, so it needs to run on the UI thread.
            BeginInvokeOnMainThread(() =>
                // Get the relevant field from the table.
                ServiceFeatureTable table = (ServiceFeatureTable) sender;
                Field typeDamageField = table.Fields.First(field => field.Name == AttributeFieldName);

                // Get the domain for the field.
                _domain = (CodedValueDomain) typeDamageField.Domain;

                // Listen for user taps on the map - this will select the feature.
                _myMapView.GeoViewTapped += MapView_Tapped;

        private async void MapView_Tapped(object sender, GeoViewInputEventArgs e)
            // Clear any existing selection.

            // Dismiss any existing callouts.

                // Perform an identify to determine if a user tapped on a feature.
                IdentifyLayerResult identifyResult = await _myMapView.IdentifyLayerAsync(_damageLayer, e.Position, 8, false);

                // Do nothing if there are no results.
                if (!identifyResult.GeoElements.Any())

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

                // Select the feature.

                // Update the UI for the selection.
            catch (Exception ex)
                ShowMessage("Error selecting feature.", ex.ToString());

        private void ShowFeatureCallout()
            // Get the current value.
            string currentAttributeValue = _selectedFeature.Attributes[AttributeFieldName].ToString();

            // Set up the UI for the callout.
            UIButton changeValueButton = new UIButton();
            changeValueButton.SetTitle($"{currentAttributeValue} - Edit", UIControlState.Normal);
            changeValueButton.SetTitleColor(View.TintColor, UIControlState.Normal);
            changeValueButton.TouchUpInside += ShowDamageTypeChoices;

            // Show the callout.
            _myMapView.ShowCalloutAt((MapPoint) _selectedFeature.Geometry, changeValueButton);

        private void ShowDamageTypeChoices(object sender, EventArgs e)
            // Show the currently selected attribute value.
            string message = $"Current value is {_selectedFeature.Attributes[AttributeFieldName]}";

            // Create the alert controller - will show current value and the options for changing the value.
            UIAlertController alertController = UIAlertController.Create("Choose a damage type.", message, UIAlertControllerStyle.Alert);

            // Get the list of valid choices - all of the coded values that aren't currently selected.
            IEnumerable<CodedValue> possibleChoices = _domain.CodedValues.Where(value => value.Name != _selectedFeature.Attributes[AttributeFieldName].ToString());

            // Add an action (shows as button) for every choice.
            foreach (CodedValue codeValue in possibleChoices)
                alertController.AddAction(UIAlertAction.Create(codeValue.Name, UIAlertActionStyle.Default, action => UpdateDamageType(codeValue.Name)));

            // Allow the user to cancel.
            alertController.AddAction(UIAlertAction.Create("Cancel", UIAlertActionStyle.Cancel, null));

            // Show the alert.
            PresentViewController(alertController, true, null);

        private async void UpdateDamageType(string selectedAttributeValue)
                // Load the feature.
                await _selectedFeature.LoadAsync();

                // Update the attribute value.
                _selectedFeature.SetAttributeValue(AttributeFieldName, selectedAttributeValue);

                // Update the table.
                await _selectedFeature.FeatureTable.UpdateFeatureAsync(_selectedFeature);

                // Update the service.
                ServiceFeatureTable table = (ServiceFeatureTable) _selectedFeature.FeatureTable;
                await table.ApplyEditsAsync();

                ShowMessage("Success!", $"Edited feature {_selectedFeature.Attributes["objectid"]}");
            catch (Exception ex)
                ShowMessage("Failed to edit feature", ex.ToString());
                // Clear the selection.
                _selectedFeature = null;

                // Dismiss any callout.

        private void ShowMessage(string title, string message)
            // Create the alert controller.
            UIAlertController alertController = UIAlertController.Create(title, message, UIAlertControllerStyle.Alert);
            alertController.AddAction(UIAlertAction.Create("OK", UIAlertActionStyle.Default, null));

            // Show the alert.
            PresentViewController(alertController, true, null);

        public override void ViewDidLoad()

        public override void LoadView()
            // Create the views.
            View = new UIView();

            _myMapView = new MapView();
            _myMapView.TranslatesAutoresizingMaskIntoConstraints = false;

            UILabel helpLabel = new UILabel
                Text = "Tap to select features to edit.",
                AdjustsFontSizeToFitWidth = true,
                TextAlignment = UITextAlignment.Center,
                BackgroundColor = UIColor.FromWhiteAlpha(0, .6f),
                TextColor = UIColor.White,
                Lines = 1,
                TranslatesAutoresizingMaskIntoConstraints = false

            // Add the views.
            View.AddSubviews(_myMapView, helpLabel);

            // Lay out the views.


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