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ArcGIS Runtime SDK for .NET

Service feature table (manual cache)

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

Display a feature layer from a service using the manual cache feature request mode.

screenshot

Use case

ServiceFeatureTable supports three request modes, which define how features are requested from the service and stored in the local table. The feature request modes have different performance characteristics. Use manual cache in scenarios where you want to explicitly control requests for features. See Table performance concepts to learn more.

How it works

  1. Set the ServiceFeatureTable.FeatureRequestMode property of the service feature table to MANUAL_CACHE before the table is loaded.
  2. Load the table.
  3. Call PopulateFromServiceAsync on the table to request features.

Relevant API

  • FeatureLayer
  • FeatureRequestMode.ManualCache
  • ServiceFeatureTable
  • ServiceFeatureTable.PopulateFromServiceAsync
  • ServiceFeatureTable.FeatureRequestMode

About the data

The U.S. National Bridge Inventory describes 600,000 bridges in the United States. The sample uses a modified copy of the inventory hosted in ArcGIS Online. The sample opens with an initial visible extent centered over Bridgeport, CT.

Additional information

In manual cache mode, features are never automatically populated from the service. All features are loaded manually using calls to PopulateFromServiceAsync.

Tags

cache, feature request mode, performance

Sample Code

<UserControl
    x:Class="ArcGISRuntime.UWP.Samples.ServiceFeatureTableManualCache.ServiceFeatureTableManualCache"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:esriUI="using:Esri.ArcGISRuntime.UI.Controls"
    mc:Ignorable="d"
    d:DesignHeight="300"
    d:DesignWidth="400">

    <Grid>
        <esriUI:MapView x:Name="MyMapView"/>
    </Grid>
</UserControl>
// Copyright 2016 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;
using Esri.ArcGISRuntime.Data;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using System;
using Windows.UI.Popups;

namespace ArcGISRuntime.UWP.Samples.ServiceFeatureTableManualCache
{
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        "Service feature table (manual cache)",
        "Data",
        "This sample demonstrates how to use a feature service in manual cache mode.",
        "")]
    public sealed partial class ServiceFeatureTableManualCache
    {

        private ServiceFeatureTable _incidentsFeatureTable;

        public ServiceFeatureTableManualCache()
        {
            InitializeComponent();

            // Create the UI, setup the control references and execute initialization 
            Initialize();
        }

        private void Initialize()
        {
            // Create new Map with basemap
            Map myMap = new Map(Basemap.CreateTopographic());

            // Create and set initial map location
            MapPoint initialLocation = new MapPoint(
                -13630484, 4545415, SpatialReferences.WebMercator);
            myMap.InitialViewpoint = new Viewpoint(initialLocation, 500000);

            // Create uri to the used feature service
            Uri serviceUri = new Uri(
               "https://sampleserver6.arcgisonline.com/arcgis/rest/services/SF311/FeatureServer/0");

            // Create feature table for the incident feature service
            _incidentsFeatureTable = new ServiceFeatureTable(serviceUri)
            {

                // Define the request mode
                FeatureRequestMode = FeatureRequestMode.ManualCache
            };

            // When feature table is loaded, populate data
            _incidentsFeatureTable.LoadStatusChanged += OnLoadedPopulateData;

            // Create FeatureLayer that uses the created table
            FeatureLayer incidentsFeatureLayer = new FeatureLayer(_incidentsFeatureTable);

            // Add created layer to the map
            myMap.OperationalLayers.Add(incidentsFeatureLayer);

            // Assign the map to the MapView
            MyMapView.Map = myMap;
        }

        private async void OnLoadedPopulateData(object sender, LoadStatusEventArgs e)
        {
            // If layer isn't loaded, do nothing
            if (e.Status != LoadStatus.Loaded)
                return;

            // Create new query object that contains parameters to query specific request types
            QueryParameters queryParameters = new QueryParameters()
            {
                WhereClause = "req_Type = 'Tree Maintenance or Damage'"
            };

            // Create list of the fields that are returned from the service
            string[] outputFields = { "*" };

            try
            {
                // Populate feature table with the data based on query
                await _incidentsFeatureTable.PopulateFromServiceAsync(queryParameters, true, outputFields);
            }
            catch (Exception ex)
            {
                await new MessageDialog(ex.ToString(), "Error").ShowAsync();
            }
        }
    }
}