Browse WFS layers

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Browse a WFS service for layers and add them to the map.

Image of browse WFS layers

Use case

Services often have multiple layers available for display. For example, a feature service for a city might have layers representing roads, land masses, building footprints, parks, and facilities. A user can choose to only show the road network and parks for a park accessibility analysis.

How to use the sample

A list of layers in the WFS service will be shown. Select a layer to display.

Some WFS services return coordinates in X,Y order, while others return coordinates in lat/long (Y,X) order. If you don't see features rendered or you see features in the wrong location, use the checkbox to change the coordinate order and reload.

How it works

  1. Create a WfsService object with a URL to a WFS feature service.
  2. Obtain a list of WfsLayerInfo from WfsService.ServiceInfo.
  3. When a layer is selected, create a WfsFeatureTable from the WfsLayerInfo.

    • Set the axis order if necessary.
  4. Create a feature layer from the feature table.
  5. Add the feature layer to the map.

Relevant API

  • FeatureLayer
  • WfsFeatureTable
  • WfsFeatureTable.AxisOrder
  • WfsLayerInfo
  • WfsService
  • WfsServiceInfo

About the data

The sample is configured with a sample WFS service, but you can load other WFS services if desired. The default service shows Seattle downtown features hosted on ArcGIS Online.

Tags

browse, catalog, feature, layers, OGC, service, web, WFS

Sample Code

BrowseWfsLayers.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.Content;
using Android.OS;
using Android.Views;
using Android.Widget;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Ogc;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI.Controls;
using System;
using System.Drawing;

namespace ArcGISRuntimeXamarin.Samples.BrowseWfsLayers
{
    [Activity]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "Browse WFS layers",
        category: "Layers",
        description: "Browse a WFS service for layers and add them to the map.",
        instructions: "A list of layers in the WFS service will be shown. Select a layer to display.",
        tags: new[] { "OGC", "WFS", "browse", "catalog", "feature", "layers", "service", "web" })]
    public class BrowseWfsLayers : Activity
    {
        // Hold references to the UI controls.
        private MapView _myMapView;
        private Switch _axisOrderSwitch;
        private ProgressBar _loadingProgressBar;
        private Button _loadLayerButton;
        private Button _loadServiceButton;
        private EditText _urlEntry;

        // Hold a reference to the WFS service info.
        private WfsServiceInfo _serviceInfo;

        // URL to the WFS service.
        private const string ServiceUrl = "https://dservices2.arcgis.com/ZQgQTuoyBrtmoGdP/arcgis/services/Seattle_Downtown_Features/WFSServer?service=wfs&request=getcapabilities";

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

            Title = "Browse WFS service for layers";

            CreateLayout();
            Initialize();
        }

        private void Initialize()
        {
            // Update the UI.
            _loadServiceButton.Text = ServiceUrl;

            // Create the map with imagery basemap.
            _myMapView.Map = new Map(BasemapStyle.ArcGISImageryStandard);

            LoadService();
        }

        private async void LoadService()
        {
            try
            {
                _loadingProgressBar.Visibility = ViewStates.Visible;
                _loadLayerButton.Enabled = false;
                _loadServiceButton.Enabled = false;

                // Create the WFS service.
                WfsService service = new WfsService(new Uri(_loadServiceButton.Text));

                // Load the WFS service.
                await service.LoadAsync();

                // Get the service metadata.
                _serviceInfo = service.ServiceInfo;
            }
            catch (Exception ex)
            {
                new AlertDialog.Builder(this).SetMessage(ex.Message).SetTitle("Error loading service").Show();
            }
            finally
            {
                // Update the UI.
                _loadingProgressBar.Visibility = ViewStates.Gone;
                _loadLayerButton.Enabled = true;
                _loadServiceButton.Enabled = true;
            }
        }

        private async void LayerMenu_LayerSelected(object sender, PopupMenu.MenuItemClickEventArgs e)
        {
            // Show the progress bar.
            _loadingProgressBar.Visibility = ViewStates.Visible;

            // Clear the existing layers.
            _myMapView.Map.OperationalLayers.Clear();

            try
            {
                // Get the selected layer info.
                WfsLayerInfo selectedLayerInfo = _serviceInfo.LayerInfos[e.Item.Order];

                // Create the WFS feature table.
                WfsFeatureTable table = new WfsFeatureTable(selectedLayerInfo);

                // Set the feature request mode to manual - only manual is supported at v100.5.
                // In this mode, you must manually populate the table - panning and zooming won't request features automatically.
                table.FeatureRequestMode = FeatureRequestMode.ManualCache;

                // Set the axis order based on the UI.
                if (_axisOrderSwitch.Checked)
                {
                    table.AxisOrder = OgcAxisOrder.Swap;
                }
                else
                {
                    table.AxisOrder = OgcAxisOrder.NoSwap;
                }

                // Populate the WFS table.
                await table.PopulateFromServiceAsync(new QueryParameters(), false, null);

                // Create a feature layer from the WFS table.
                FeatureLayer wfsFeatureLayer = new FeatureLayer(table);

                // Choose a renderer for the layer based on the table.
                wfsFeatureLayer.Renderer = GetRendererForTable(table) ?? wfsFeatureLayer.Renderer;

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

                // Zoom to the extent of the layer.
                await _myMapView.SetViewpointGeometryAsync(selectedLayerInfo.Extent, 50);
            }
            catch (Exception exception)
            {
                System.Diagnostics.Debug.WriteLine(exception);
                new AlertDialog.Builder(this).SetMessage(exception.ToString()).SetTitle("Couldn't load layer.").Show();
            }
            finally
            {
                // Hide the progress bar.
                _loadingProgressBar.Visibility = ViewStates.Gone;
            }
        }

        private void ChooseLayer_Clicked(object sender, EventArgs e)
        {
            // Get a reference to the button.
            Button loadButton = (Button)sender;

            // Create menu to show layer options.
            PopupMenu layerMenu = new PopupMenu(this, loadButton);
            layerMenu.MenuItemClick += LayerMenu_LayerSelected;

            // Create menu options.
            int index = 0;
            foreach (WfsLayerInfo layerInfo in _serviceInfo.LayerInfos)
            {
                layerMenu.Menu.Add(0, index, index, layerInfo.Title);
                index++;
            }

            // Show menu in the view.
            layerMenu.Show();
        }

        private void ServiceClicked(object sender, EventArgs e)
        {
            // Create a text-entry prompt for changing the WFS url.
            AlertDialog.Builder builder = new AlertDialog.Builder(this);
            builder.SetTitle("Set WFS service URL");

            // Create the text entry.
            _urlEntry = new EditText(this);
            _urlEntry.Text = _loadServiceButton.Text;
            _urlEntry.InputType = Android.Text.InputTypes.TextVariationUri;
            builder.SetView(_urlEntry);

            // Finish building the dialog and display it.
            builder.SetPositiveButton("Load", ServicePressed);
            builder.SetCancelable(true);
            builder.Show();
        }

        private void ServicePressed(object sender, DialogClickEventArgs e)
        {
            _loadServiceButton.Text = _urlEntry.Text;
            LoadService();
        }

        private Renderer GetRendererForTable(FeatureTable table)
        {
            switch (table.GeometryType)
            {
                case GeometryType.Point:
                case GeometryType.Multipoint:
                    return new SimpleRenderer(new SimpleMarkerSymbol(SimpleMarkerSymbolStyle.Circle, Color.Blue, 4));

                case GeometryType.Polygon:
                case GeometryType.Envelope:
                    return new SimpleRenderer(new SimpleFillSymbol(SimpleFillSymbolStyle.Solid, Color.Blue, null));

                case GeometryType.Polyline:
                    return new SimpleRenderer(new SimpleLineSymbol(SimpleLineSymbolStyle.Solid, Color.Blue, 1));
            }

            return null;
        }

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

            // Add the button.
            _loadServiceButton = new Button(this);
            _loadServiceButton.Text = "Choose a layer";
            _loadServiceButton.Click += ServiceClicked;
            _loadServiceButton.Enabled = false;
            layout.AddView(_loadServiceButton);

            // Add the axis order switch.
            _axisOrderSwitch = new Switch(this);
            _axisOrderSwitch.Text = "Swap coordinates";
            layout.AddView(_axisOrderSwitch);

            // Add the button.
            _loadLayerButton = new Button(this);
            _loadLayerButton.Text = "Choose a layer";
            _loadLayerButton.Click += ChooseLayer_Clicked;
            _loadLayerButton.Enabled = false;
            layout.AddView(_loadLayerButton);

            // Add the loading indicator.
            _loadingProgressBar = new ProgressBar(this);
            _loadingProgressBar.Indeterminate = true;
            _loadingProgressBar.Visibility = ViewStates.Gone;
            layout.AddView(_loadingProgressBar);

            // Add the map view to the layout.
            _myMapView = new MapView(this);
            layout.AddView(_myMapView);

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

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