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ArcGIS Runtime SDK for .NET

Edit feature attachments

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

Add, delete, and download attachments for features from a service.

Edit Feature Attachments

How to use the sample

Tap a feature to load its attachments. Use the buttons to preview, delete, or add attachments.

How it works

  1. Create a service feature table from a URL.
  2. Create a FeatureLayer from the service feature table.
  3. Select features from the feature layer, FeatureLayer.SelectFeatures().
  4. To fetch the feature's attachments, cast to an ArcGISFeature and useArcGISFeature.GetAttachmentsAsync().
  5. To add an attachment to the selected ArcGISFeature, use ArcGISFeature.AddAttachmentAsync().
  6. To delete an attachment from the selected ArcGISFeature, use the ArcGISFeature.DeleteAttachmentAsync().
  7. After a change, apply the changes to the server using ServiceFeatureTable.ApplyEditsAsync().

Relevant API

  • ServiceFeatureTable
  • FeatureLayer
  • GetAttachmentsAsync
  • GetDataAsync
  • DeleteAttachmentAsync
  • UpdateFeatureAsync
  • ApplyEditsAsync

Tags

Edit and Manage Data

Sample Code

<?xml version="1.0" encoding="utf-8" ?>

<ContentPage
    x:Class="ArcGISRuntimeXamarin.Samples.EditFeatureAttachments.EditFeatureAttachments"
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:esriUI="clr-namespace:Esri.ArcGISRuntime.Xamarin.Forms;assembly=Esri.ArcGISRuntime.Xamarin.Forms"
    xmlns:resources="clr-namespace:Forms.Resources;assembly=ArcGISRuntime">
    <RelativeLayout>
        <esriUI:MapView
            x:Name="MyMapView"
            BindingContext="{x:Reference Name=ResponsiveFormContainer}"
            Style="{StaticResource MapWithFormStyle}" />
        <resources:ResponsiveFormContainer x:Name="ResponsiveFormContainer">
            <Grid>
                <StackLayout Orientation="Vertical">
                    <Label
                        Margin="0,0,0,5"
                        FontAttributes="Bold"
                        HorizontalTextAlignment="Center"
                        Text="Tap features to select." />
                    <ListView
                        x:Name="AttachmentsListBox"
                        HeightRequest="100"
                        IsEnabled="False">
                        <!--  ItemTemplate defines how each item (Attachment) is rendered.  -->
                        <ListView.ItemTemplate>
                            <DataTemplate>
                                <ViewCell>
                                    <Grid>
                                        <Grid.ColumnDefinitions>
                                            <ColumnDefinition Width="*" />
                                            <ColumnDefinition Width="Auto" />
                                            <ColumnDefinition Width="Auto" />
                                        </Grid.ColumnDefinitions>
                                        <Label
                                            Margin="5,0,5,0"
                                            Text="{Binding Name}"
                                            VerticalTextAlignment="Center" />
                                        <!--  DataTemplate sets the item as the button's DataContext automatically.  -->
                                        <Button
                                            Grid.Column="1"
                                            Margin="0,0,5,0"
                                            Clicked="DownloadAttachment_Click"
                                            Text="🔎"
                                            VerticalOptions="End" />
                                        <!--  These symbols are emojis. Use Win+. on Windows to open the emoji picker.  -->
                                        <Button
                                            Grid.Column="2"
                                            Clicked="DeleteAttachment_Click"
                                            Text="🗑"
                                            VerticalOptions="End" />
                                    </Grid>
                                </ViewCell>
                            </DataTemplate>
                        </ListView.ItemTemplate>
                    </ListView>
                    <Button
                        x:Name="AddAttachmentButton"
                        Margin="0,5,0,5"
                        Clicked="AddAttachment_Click"
                        IsEnabled="False"
                        Text="Add attachment" />
                    <ActivityIndicator
                        x:Name="AttachmentActivityIndicator"
                        IsRunning="True"
                        IsVisible="False" />
                </StackLayout>
            </Grid>
        </resources:ResponsiveFormContainer>
    </RelativeLayout>
</ContentPage>
// 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 Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Xamarin.Forms;
// Custom code is needed for presenting the image picker on iOS.
#if __IOS__
using Foundation;
using UIKit;
#else
using Plugin.FilePicker;
using Plugin.FilePicker.Abstractions;
#endif

namespace ArcGISRuntimeXamarin.Samples.EditFeatureAttachments
{
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        "Edit feature attachments",
        "Data",
        "Add, delete, and download attachments for features from a service.",
        "")]
    public partial class EditFeatureAttachments : ContentPage
    {
        // 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 recently selected feature.
        private ArcGISFeature _selectedFeature;

        public EditFeatureAttachments()
        {
            InitializeComponent();
            Initialize();
        }

        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));

            // 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.
            MyMapView.GeoViewTapped += MapView_Tapped;

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

        private async void MapView_Tapped(object sender, Esri.ArcGISRuntime.Xamarin.Forms.GeoViewInputEventArgs e)
        {
            // Clear any existing selection.
            _damageLayer.ClearSelection();
            _selectedFeature = null;

            // Reset the UI.
            AttachmentsListBox.IsEnabled = false;
            AttachmentsListBox.ItemsSource = null;
            AddAttachmentButton.IsEnabled = false;

            try
            {
                // Perform an identify to determine if a user tapped on a feature.
                IdentifyLayerResult identifyResult = await MyMapView.IdentifyLayerAsync(_damageLayer, e.Position, 2, false);

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

                // Get the selected feature as an ArcGISFeature. It is assumed that all GeoElements in the result are of type ArcGISFeature.
                GeoElement tappedElement = identifyResult.GeoElements.First();
                ArcGISFeature tappedFeature = (ArcGISFeature) tappedElement;

                // Select the feature in the UI and hold a reference to the tapped feature in a field.
                _damageLayer.SelectFeature(tappedFeature);
                _selectedFeature = tappedFeature;

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

                // Get the attachments.
                IReadOnlyList<Attachment> attachments = await tappedFeature.GetAttachmentsAsync();

                // Populate the UI with a list of attachments that have a content type of image/jpeg.
                AttachmentsListBox.ItemsSource = attachments.Where(attachment => attachment.ContentType == "image/jpeg");
                AttachmentsListBox.IsEnabled = true;
                AddAttachmentButton.IsEnabled = true;
            }
            catch (Exception ex)
            {
                await Application.Current.MainPage.DisplayAlert("Error selecting feature", ex.ToString(), "OK");
            }
        }

        private async void AddAttachment_Click(object sender, EventArgs e)
        {
            if (_selectedFeature == null)
            {
                return;
            }

            // Adjust the UI.
            AddAttachmentButton.IsEnabled = false;
            AttachmentActivityIndicator.IsVisible = true;

            // Get the file.
            string contentType = "image/jpeg";

            try
            {
                byte[] attachmentData;
                string filename;

                // Xamarin.Plugin.FilePicker shows the iCloud picker (not photo picker) on iOS.
                // This iOS code shows the photo picker.
#if __IOS__
                Stream imageStream = await GetImageStreamAsync();
                if (imageStream == null)
                {
                    return;
                }

                attachmentData = new byte[imageStream.Length];
                imageStream.Read(attachmentData, 0, attachmentData.Length);
                filename = _filename ?? "file1.jpeg";
#else
                // Show a file picker - this uses the Xamarin.Plugin.FilePicker NuGet package.
                FileData fileData = await CrossFilePicker.Current.PickFile(new[] {".jpg", ".jpeg"});
                if (fileData == null)
                {
                    return;
                }

                if (!fileData.FileName.EndsWith(".jpg") && !fileData.FileName.EndsWith(".jpeg"))
                {
                    await Application.Current.MainPage.DisplayAlert("Try again!", "This sample only allows uploading jpg files.", "OK");
                    return;
                }

                attachmentData = fileData.DataArray;
                filename = fileData.FileName;
#endif
                // Add the attachment.
                // The contentType string is the MIME type for JPEG files, image/jpeg.
                await _selectedFeature.AddAttachmentAsync(filename, contentType, attachmentData);

                // Get a reference to the feature's service feature table.
                ServiceFeatureTable serviceTable = (ServiceFeatureTable) _selectedFeature.FeatureTable;

                // Apply the edits to the service feature table.
                await serviceTable.ApplyEditsAsync();

                // Update UI.
                _selectedFeature.Refresh();
                AttachmentsListBox.ItemsSource = await _selectedFeature.GetAttachmentsAsync();

                await Application.Current.MainPage.DisplayAlert("Success!", "Successfully added attachment", "OK");
            }
            catch (Exception exception)
            {
                await Application.Current.MainPage.DisplayAlert("Error adding attachment", exception.ToString(), "OK");
            }
            finally
            {
                // Adjust the UI.
                AddAttachmentButton.IsEnabled = true;
                AttachmentActivityIndicator.IsVisible = false;
            }
        }

        private async void DeleteAttachment_Click(object sender, EventArgs e)
        {
            AttachmentActivityIndicator.IsVisible = true;

            try
            {
                // Get the attachment that should be deleted.
                Button sendingButton = (Button) sender;
                Attachment selectedAttachment = (Attachment) sendingButton.BindingContext;

                // Delete the attachment.
                await _selectedFeature.DeleteAttachmentAsync(selectedAttachment);

                // Get a reference to the feature's service feature table.
                ServiceFeatureTable serviceTable = (ServiceFeatureTable) _selectedFeature.FeatureTable;

                // Apply the edits to the service feature table.
                await serviceTable.ApplyEditsAsync();

                // Update UI.
                _selectedFeature.Refresh();
                AttachmentsListBox.ItemsSource = await _selectedFeature.GetAttachmentsAsync();

                // Show success message.
                await Application.Current.MainPage.DisplayAlert("Success!", "Successfully deleted attachment", "OK");
            }
            catch (Exception exception)
            {
                await Application.Current.MainPage.DisplayAlert("Error deleting attachment", exception.ToString(), "OK");
            }
            finally
            {
                AttachmentActivityIndicator.IsVisible = false;
            }
        }

        private async void DownloadAttachment_Click(object sender, EventArgs e)
        {
            try
            {
                // Get a reference to the button that raised the event.
                Button sendingButton = (Button) sender;

                // Get the attachment from the button's DataContext. The button's DataContext is set by the list view.
                Attachment selectedAttachment = (Attachment) sendingButton.BindingContext;

                if (selectedAttachment.ContentType.Contains("image"))
                {
                    // Create a preview and show it.
                    ContentPage previewPage = new ContentPage();
                    previewPage.Title = "Attachment preview";
                    Image imageView = new Image();
                    Stream contentStream = await selectedAttachment.GetDataAsync();
                    imageView.Source = ImageSource.FromStream(() => contentStream);
                    previewPage.Content = imageView;
                    await Navigation.PushAsync(previewPage);
                }
                else
                {
                    await Application.Current.MainPage.DisplayAlert("Can't show attachment", "This sample can only show image attachments.", "OK");
                }
            }
            catch (Exception exception)
            {
                await Application.Current.MainPage.DisplayAlert("Error reading attachment", exception.ToString(), "OK");
            }
        }

        // Image picker implementation.
        // Xamarin.Plugin.FilePicker shows an iCloud file picker; comment this out
        // and use the cross-platform implementation if that's what you want.
        // Note: code adapted from https://docs.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/dependency-service/photo-picker
#if __IOS__
        private TaskCompletionSource<Stream> _taskCompletionSource;
        private UIImagePickerController _imagePicker;
        private string _filename;

        private Task<Stream> GetImageStreamAsync()
        {
            // Create and define UIImagePickerController.
            _imagePicker = new UIImagePickerController
            {
                SourceType = UIImagePickerControllerSourceType.PhotoLibrary,
                MediaTypes = UIImagePickerController.AvailableMediaTypes(UIImagePickerControllerSourceType.PhotoLibrary)
            };

            // Set event handlers.
            _imagePicker.FinishedPickingMedia += OnImagePickerFinishedPickingMedia;
            _imagePicker.Canceled += OnImagePickerCancelled;

            // Present UIImagePickerController.
            UIWindow window = UIApplication.SharedApplication.KeyWindow;
            var viewController = window.RootViewController;
            viewController.PresentModalViewController(_imagePicker, true);

            // Return Task object.
            _taskCompletionSource = new TaskCompletionSource<Stream>();
            return _taskCompletionSource.Task;
        }

        void OnImagePickerFinishedPickingMedia(object sender, UIImagePickerMediaPickedEventArgs args)
        {
            UIImage image = args.EditedImage ?? args.OriginalImage;
            _filename = args.ImageUrl.LastPathComponent;
            if (image != null)
            {
                // Convert UIImage to .NET Stream object.
                NSData data = image.AsJPEG(1);
                Stream stream = data.AsStream();

                UnregisterEventHandlers();

                // Set the Stream as the completion of the Task.
                _taskCompletionSource.SetResult(stream);
            }
            else
            {
                UnregisterEventHandlers();
                _taskCompletionSource.SetResult(null);
            }

            _imagePicker.DismissModalViewController(true);
        }

        void OnImagePickerCancelled(object sender, EventArgs args)
        {
            UnregisterEventHandlers();
            _taskCompletionSource.SetResult(null);
            _imagePicker.DismissModalViewController(true);
        }

        void UnregisterEventHandlers()
        {
            _imagePicker.FinishedPickingMedia -= OnImagePickerFinishedPickingMedia;
            _imagePicker.Canceled -= OnImagePickerCancelled;
        }
#endif
    }
}