Delete features from an online feature service.
Use case
Sometimes users may want to delete features from an online feature service.
How to use the sample
To delete a feature, tap it, then tap 'Delete incident'.
How it works
- Create a
ServiceFeatureTable
object from a URL. - Create a
FeatureLayer
object from the service feature table. - Select features from the feature layer via
FeatureLayer.SelectFeatures()
. - Remove the selected features from the service feature table using
ServiceFeatureTable.DeleteFeatureAsync()
. - Update the table on the server using
ServiceFeatureTable.ApplyEditsAsync()
.
Relevant API
- Feature
- FeatureLayer
- ServiceFeatureTable
Tags
deletion, feature, online, Service, table
Sample Code
DeleteFeatures.cs
// 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 ArcGISRuntime;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.UI.Controls;
using Foundation;
using System;
using System.Linq;
using UIKit;
namespace ArcGISRuntimeXamarin.Samples.DeleteFeatures
{
[Register("DeleteFeatures")]
[ArcGISRuntime.Samples.Shared.Attributes.Sample(
name: "Delete features (feature service)",
category: "Data",
description: "Delete features from an online feature service.",
instructions: "To delete a feature, tap it, then tap 'Delete incident'.",
tags: new[] { "Service", "deletion", "feature", "online", "table" })]
public class DeleteFeatures : UIViewController
{
// Hold references to UI controls.
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;
public DeleteFeatures()
{
Title = "Delete features";
}
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);
// Zoom to the United States.
_myMapView.SetViewpointCenterAsync(new MapPoint(-10800000, 4500000, SpatialReferences.WebMercator), 3e7);
}
private async void MapView_Tapped(object sender, GeoViewInputEventArgs e)
{
// Clear any existing selection.
_damageLayer.ClearSelection();
// Dismiss any existing callouts.
_myMapView.DismissCallout();
try
{
// 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())
{
return;
}
// Otherwise, get the ID of the first result.
long featureId = (long) identifyResult.GeoElements.First().Attributes["objectid"];
// Get the feature by constructing a query and running it.
QueryParameters qp = new QueryParameters();
qp.ObjectIds.Add(featureId);
FeatureQueryResult queryResult = await _damageLayer.FeatureTable.QueryFeaturesAsync(qp);
Feature tappedFeature = queryResult.First();
// Select the feature.
_damageLayer.SelectFeature(tappedFeature);
// Show the callout.
ShowDeletionCallout(tappedFeature);
}
catch (Exception ex)
{
ShowMessage(ex.ToString(), "There was a problem.");
}
}
private void ShowDeletionCallout(Feature tappedFeature)
{
// Create a button for deleting the feature.
UIButton deleteButton = new UIButton();
deleteButton.SetTitle("Delete feature", UIControlState.Normal);
deleteButton.SetTitleColor(View.TintColor, UIControlState.Normal);
// Handle button clicks.
void DeleteFeature_click(object sender, EventArgs e)
{
// Unsubscribe from event.
deleteButton.TouchUpInside -= DeleteFeature_click;
// Delete the feature.
DeleteFeature(tappedFeature);
// Dismiss the callout.
_myMapView.DismissCallout();
}
deleteButton.TouchUpInside += DeleteFeature_click;
// Show the callout.
_myMapView.ShowCalloutAt((MapPoint) tappedFeature.Geometry, deleteButton);
}
private async void DeleteFeature(Feature featureToDelete)
{
try
{
// Delete the feature.
await _damageLayer.FeatureTable.DeleteFeatureAsync(featureToDelete);
// Sync the change with the service.
ServiceFeatureTable serviceTable = (ServiceFeatureTable) _damageLayer.FeatureTable;
await serviceTable.ApplyEditsAsync();
// Show a message confirming the deletion.
ShowMessage($"Deleted feature with ID {featureToDelete.Attributes["objectid"]}", "Success!");
}
catch (Exception ex)
{
ShowMessage(ex.ToString(), "Couldn't delete feature");
}
}
private void ShowMessage(string message, string title)
{
// 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()
{
base.ViewDidLoad();
Initialize();
}
public override void LoadView()
{
// Create the views.
View = new UIView() { BackgroundColor = ApplicationTheme.BackgroundColor };
_myMapView = new MapView();
_myMapView.TranslatesAutoresizingMaskIntoConstraints = false;
UILabel helpLabel = new UILabel
{
Text = "Tap to select a feature for deletion.",
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.
NSLayoutConstraint.ActivateConstraints(new[]
{
_myMapView.TopAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.TopAnchor),
_myMapView.BottomAnchor.ConstraintEqualTo(View.BottomAnchor),
_myMapView.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
_myMapView.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
helpLabel.TopAnchor.ConstraintEqualTo(View.SafeAreaLayoutGuide.TopAnchor),
helpLabel.LeadingAnchor.ConstraintEqualTo(View.LeadingAnchor),
helpLabel.TrailingAnchor.ConstraintEqualTo(View.TrailingAnchor),
helpLabel.HeightAnchor.ConstraintEqualTo(40)
});
}
public override void ViewWillAppear(bool animated)
{
base.ViewWillAppear(animated);
// Subscribe to events.
_myMapView.GeoViewTapped += MapView_Tapped;
}
public override void ViewDidDisappear(bool animated)
{
base.ViewDidDisappear(animated);
// Unsubscribe from events, per best practice.
_myMapView.GeoViewTapped -= MapView_Tapped;
}
}
}