Attribute Query Online

This sample demonstrates performing an attribute query, adding the results to the map and a DataGrid, and zooming to the result. To use the sample, select a state from the drop-down menu in the upper right corner of the application.

In the sample's code-behind, a QueryTask is used to query a states map service layer based on the name selected in the drop-down menu. The result is then added as a Graphic to the map and displayed in the DataGrid.

XAML

<UserControl x:Class="ArcGISWPFSDK.AttributeQuery"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:esri="http://schemas.esri.com/arcgis/client/2009">
    <Grid x:Name="LayoutRoot" Background="White">

        <Grid.Resources>
            <esri:SimpleFillSymbol x:Key="DefaultFillSymbol" Fill="#500000FF" BorderBrush="Blue" BorderThickness="1" />
            <LinearGradientBrush x:Key="PanelGradient" EndPoint="0.5,1" StartPoint="0.5,0">
                <LinearGradientBrush.RelativeTransform>
                    <TransformGroup>
                        <ScaleTransform CenterY="0.5" CenterX="0.5"/>
                        <SkewTransform CenterY="0.5" CenterX="0.5"/>
                        <RotateTransform Angle="176" CenterY="0.5" CenterX="0.5"/>
                        <TranslateTransform/>
                    </TransformGroup>
                </LinearGradientBrush.RelativeTransform>
                <GradientStop Color="#FF145787" Offset="0.16"/>
                <GradientStop Color="#FF3D7FAC" Offset="0.502"/>
                <GradientStop Color="#FF88C5EF" Offset="0.984"/>
            </LinearGradientBrush>
        </Grid.Resources>

        <esri:Map x:Name="MyMap" Extent="-15000000,2000000,-7000000,8000000" WrapAround="True">
            <esri:ArcGISTiledMapServiceLayer ID="StreetMapLayer" 
                      Url="http://services.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer"/>
            <esri:GraphicsLayer ID="MyGraphicsLayer" />
        </esri:Map>

        <StackPanel Orientation="Vertical" Margin="10" HorizontalAlignment="Right" VerticalAlignment="Top" >
            <Grid x:Name="QueryGrid" HorizontalAlignment="Right" VerticalAlignment="Top" Margin="0,7,7,0" >
                <Rectangle Fill="{StaticResource PanelGradient}" Stroke="Gray"  RadiusX="10" RadiusY="10" Margin="0,0,0,5">
                    <Rectangle.Effect>
                        <DropShadowEffect/>
                    </Rectangle.Effect>
                </Rectangle>
                <TextBlock x:Name="DataDisplayTitleBottom" Text="Query a layer" Foreground="White" FontSize="12" 
                      Margin="10,3,0,5" />
                <StackPanel Orientation="Vertical" Margin="15" HorizontalAlignment="Center" VerticalAlignment="Top" >
                    <ComboBox x:Name="QueryComboBox" MinWidth="150" SelectionChanged="QueryComboBox_SelectionChanged"
                         Margin="5,10,5,5" >
                    </ComboBox>
                    <ScrollViewer x:Name="DataGridScrollViewer" HorizontalScrollBarVisibility="Hidden" VerticalScrollBarVisibility="Auto"  
                         Width="230" MaxHeight="340" Visibility="Collapsed">
                        <DataGrid x:Name="QueryDetailsDataGrid" AutoGenerateColumns="False" HeadersVisibility="None" 
                              Background="White">
                            <DataGrid.Columns>
                                <DataGridTextColumn Width="95" Binding="{Binding Path=Key}" FontWeight="Bold" IsReadOnly="True"/>
                                <DataGridTextColumn Width="115" Binding="{Binding Path=Value}" IsReadOnly="True"/>
                            </DataGrid.Columns>
                        </DataGrid>
                    </ScrollViewer>
                </StackPanel>
            </Grid>
        </StackPanel>

    </Grid>
</UserControl>

C#

using System;
using System.Windows;
using System.Windows.Controls;
using ESRI.ArcGIS.Client;
using ESRI.ArcGIS.Client.Tasks;

namespace ArcGISWPFSDK
{
    public partial class AttributeQuery : UserControl
    {
        public AttributeQuery()
        {
            InitializeComponent();

            QueryTask queryTask = new QueryTask("http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Census_USA/MapServer/5");
            queryTask.ExecuteCompleted += QueryTask_ExecuteCompleted;
            queryTask.Failed += QueryTask_Failed;

            ESRI.ArcGIS.Client.Tasks.Query query = new ESRI.ArcGIS.Client.Tasks.Query();

            // Specify fields to return from initial query
            query.OutFields.AddRange(new string[] { "STATE_NAME" });

            // This query will just populate the drop-down, so no need to return geometry
            query.ReturnGeometry = false;

            // Return all features
            query.Where = "1=1";
            queryTask.ExecuteAsync(query, "initial");
        }

        private void QueryComboBox_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            if (QueryComboBox.SelectedItem.ToString().Contains("Select..."))
                return;

            QueryTask queryTask = new QueryTask("http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Census_USA/MapServer/5");
            queryTask.ExecuteCompleted += QueryTask_ExecuteCompleted;
            queryTask.Failed += QueryTask_Failed;

            ESRI.ArcGIS.Client.Tasks.Query query = new ESRI.ArcGIS.Client.Tasks.Query();
            query.OutFields.Add("*");
            query.ReturnGeometry = true;
            query.Text = QueryComboBox.SelectedItem.ToString();
            query.OutSpatialReference = MyMap.SpatialReference;

            queryTask.ExecuteAsync(query);
        }

        private void QueryTask_ExecuteCompleted(object sender, ESRI.ArcGIS.Client.Tasks.QueryEventArgs args)
        {
            FeatureSet featureSet = args.FeatureSet;

            // If initial query to populate states combobox
            if ((args.UserState as string) == "initial")
            {
                // Just show on initial load
                QueryComboBox.Items.Add("Select...");

                foreach (Graphic graphic in args.FeatureSet.Features)
                {
                    QueryComboBox.Items.Add(graphic.Attributes["STATE_NAME"].ToString());
                }

                QueryComboBox.SelectedIndex = 0;
                return;
            }

            // Remove the first entry if "Select..."
            if (QueryComboBox.Items[0].ToString().Contains("Select..."))
                QueryComboBox.Items.RemoveAt(0);

            // If an item has been selected            
            GraphicsLayer graphicsLayer = MyMap.Layers["MyGraphicsLayer"] as GraphicsLayer;
            graphicsLayer.ClearGraphics();

            if (featureSet != null && featureSet.Features.Count > 0)
            {
                // Show selected feature attributes in DataGrid
                Graphic selectedFeature = featureSet.Features[0];

                QueryDetailsDataGrid.ItemsSource = selectedFeature.Attributes;

                // Hightlight selected feature
                selectedFeature.Symbol = LayoutRoot.Resources["DefaultFillSymbol"] as ESRI.ArcGIS.Client.Symbols.Symbol;
                graphicsLayer.Graphics.Add(selectedFeature);

                // Zoom to selected feature (define expand percentage)
                ESRI.ArcGIS.Client.Geometry.Envelope selectedFeatureExtent = selectedFeature.Geometry.Extent;

                double expandPercentage = 30;

                double widthExpand = selectedFeatureExtent.Width * (expandPercentage / 100);
                double heightExpand = selectedFeatureExtent.Height * (expandPercentage / 100);

                ESRI.ArcGIS.Client.Geometry.Envelope displayExtent = new ESRI.ArcGIS.Client.Geometry.Envelope(
                selectedFeatureExtent.XMin - (widthExpand / 2),
                selectedFeatureExtent.YMin - (heightExpand / 2),
                selectedFeatureExtent.XMax + (widthExpand / 2),
                selectedFeatureExtent.YMax + (heightExpand / 2));

                MyMap.ZoomTo(displayExtent);

                // If DataGrid not visible (initial load), show it
                if (DataGridScrollViewer.Visibility == Visibility.Collapsed)
                {
                    DataGridScrollViewer.Visibility = Visibility.Visible;
                    QueryGrid.Height = Double.NaN;
                    QueryGrid.UpdateLayout();
                }
            }
            else
            {
                QueryDetailsDataGrid.ItemsSource = null;
                DataGridScrollViewer.Visibility = Visibility.Collapsed;
                QueryGrid.Height = Double.NaN;
                QueryGrid.UpdateLayout();
            }
        }

        private void QueryTask_Failed(object sender, TaskFailedEventArgs args)
        {
            MessageBox.Show("Query failed: " + args.Error);
        }
    }
}

VB.NET

Imports System.Windows
Imports System.Windows.Controls
Imports ESRI.ArcGIS.Client
Imports ESRI.ArcGIS.Client.Tasks

Namespace ArcGISWPFSDK
    Partial Public Class AttributeQuery
        Inherits UserControl
        Public Sub New()
            InitializeComponent()

            Dim queryTask As New QueryTask("http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Census_USA/MapServer/5")
            AddHandler queryTask.ExecuteCompleted, AddressOf QueryTask_ExecuteCompleted
            AddHandler queryTask.Failed, AddressOf QueryTask_Failed

            Dim query As New ESRI.ArcGIS.Client.Tasks.Query()

            ' Specify fields to return from initial query
            query.OutFields.AddRange(New String() {"STATE_NAME"})

            ' This query will just populate the drop-down, so no need to return geometry
            query.ReturnGeometry = False

            ' Return all features
            query.Where = "1=1"
            queryTask.ExecuteAsync(query, "initial")
        End Sub

        Private Sub QueryComboBox_SelectionChanged(sender As Object, e As SelectionChangedEventArgs)
            If QueryComboBox.SelectedItem.ToString().Contains("Select...") Then
                Return
            End If

            Dim queryTask As New QueryTask("http://sampleserver1.arcgisonline.com/ArcGIS/rest/services/Demographics/ESRI_Census_USA/MapServer/5")
            AddHandler queryTask.ExecuteCompleted, AddressOf QueryTask_ExecuteCompleted
            AddHandler queryTask.Failed, AddressOf QueryTask_Failed

            Dim query As New ESRI.ArcGIS.Client.Tasks.Query()
            query.OutFields.Add("*")
            query.ReturnGeometry = True
            query.Text = QueryComboBox.SelectedItem.ToString()
            query.OutSpatialReference = MyMap.SpatialReference

            queryTask.ExecuteAsync(query)
        End Sub

        Private Sub QueryTask_ExecuteCompleted(sender As Object, args As ESRI.ArcGIS.Client.Tasks.QueryEventArgs)
            Dim featureSet As FeatureSet = args.FeatureSet

            ' If initial query to populate states combobox
            If TryCast(args.UserState, String) = "initial" Then
                ' Just show on initial load
                QueryComboBox.Items.Add("Select...")

                For Each graphic As Graphic In args.FeatureSet.Features
                    QueryComboBox.Items.Add(graphic.Attributes("STATE_NAME").ToString())
                Next

                QueryComboBox.SelectedIndex = 0
                Return
            End If

            ' Remove the first entry if "Select..."
            If QueryComboBox.Items(0).ToString().Contains("Select...") Then
                QueryComboBox.Items.RemoveAt(0)
            End If

            ' If an item has been selected            
            Dim graphicsLayer As GraphicsLayer = TryCast(MyMap.Layers("MyGraphicsLayer"), GraphicsLayer)
            graphicsLayer.ClearGraphics()

            If featureSet IsNot Nothing AndAlso featureSet.Features.Count > 0 Then
                ' Show selected feature attributes in DataGrid
                Dim selectedFeature As Graphic = featureSet.Features(0)

                QueryDetailsDataGrid.ItemsSource = selectedFeature.Attributes

                ' Hightlight selected feature
                selectedFeature.Symbol = TryCast(LayoutRoot.Resources("DefaultFillSymbol"), ESRI.ArcGIS.Client.Symbols.Symbol)
                graphicsLayer.Graphics.Add(selectedFeature)

                ' Zoom to selected feature (define expand percentage)
                Dim selectedFeatureExtent As ESRI.ArcGIS.Client.Geometry.Envelope = selectedFeature.Geometry.Extent

                Dim expandPercentage As Double = 30

                Dim widthExpand As Double = selectedFeatureExtent.Width * (expandPercentage / 100)
                Dim heightExpand As Double = selectedFeatureExtent.Height * (expandPercentage / 100)

                Dim displayExtent As New ESRI.ArcGIS.Client.Geometry.Envelope(selectedFeatureExtent.XMin - (widthExpand / 2), selectedFeatureExtent.YMin - (heightExpand / 2), selectedFeatureExtent.XMax + (widthExpand / 2), selectedFeatureExtent.YMax + (heightExpand / 2))

                MyMap.ZoomTo(displayExtent)

                ' If DataGrid not visible (initial load), show it
                If DataGridScrollViewer.Visibility = Visibility.Collapsed Then
                    DataGridScrollViewer.Visibility = Visibility.Visible
                    QueryGrid.Height = [Double].NaN
                    QueryGrid.UpdateLayout()
                End If
            Else
                QueryDetailsDataGrid.ItemsSource = Nothing
                DataGridScrollViewer.Visibility = Visibility.Collapsed
                QueryGrid.Height = [Double].NaN
                QueryGrid.UpdateLayout()
            End If
        End Sub

        Private Sub QueryTask_Failed(sender As Object, args As TaskFailedEventArgs)
            MessageBox.Show("Query failed: " & Convert.ToString(args.[Error]))
        End Sub
    End Class
End Namespace