방법: 데이터 바인딩 동작 사용자 지정(WCF Data Services)
WCF Data Services 를 사용하면 바인딩 컬렉션에 개체가 추가 또는 제거되거나 속성 변경이 검색될 때 DataServiceCollection에서 호출하는 사용자 지정 논리를 제공할 수 있습니다. 이 사용자 지정 논리는 사용자 지정 메서드가 완료될 때 기본 동작이 수행되어야 하는 경우 false 값을 반환하고, 이벤트의 후속 처리가 중지되어야 하는 경우 true를 반환하는 메서드로 제공되며 Func 대리자로 참조됩니다.
이 항목의 예제에서는 DataServiceCollection의 entityChanged 및 entityCollectionChanged 매개 변수에 대해 모두 사용자 지정 메서드를 제공합니다. 이 항목의 예제에서는 Northwind 샘플 데이터 서비스 및 자동 생성된 클라이언트 데이터 서비스 클래스를 사용합니다. 이 서비스 및 클라이언트 데이터 클래스는 WCF Data Services 퀵 스타트를 완료하면 만들어집니다.
예제
XAML 파일에 대한 다음 코드 숨김 페이지에서는 바인딩 컬렉션에 바인딩된 데이터가 변경될 때 호출되는 사용자 지정 메서드를 사용하여 DataServiceCollection을 만듭니다. CollectionChanged 이벤트가 발생할 경우 제공된 메서드는 바인딩 컬렉션에서 제거된 항목이 데이터 서비스에서 삭제되지 않도록 합니다. PropertyChanged 이벤트가 발생할 경우 ShipDate 값의 유효성이 검사되어 이미 운송된 주문이 변경되지 않도록 합니다.
Imports System
Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Data
Imports System.Windows.Documents
Imports System.Windows.Input
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
Imports System.Windows.Navigation
Imports System.Windows.Shapes
Imports System.Data.Services.Client
Imports NorthwindClient.Northwind
Imports System.Collections.Specialized
Partial Public Class CustomerOrdersCustom
Inherits Window
Private context As NorthwindEntities
Private trackedCustomers As DataServiceCollection(Of Customer)
Private Const customerCountry As String = "Germany"
Private Const svcUri As String = "https://localhost:12345/Northwind.svc/"
Private Sub Window_Loaded(ByVal sender As Object, ByVal e As RoutedEventArgs)
Try
' Initialize the context for the data service.
context = New NorthwindEntities(New Uri(svcUri))
' Create a LINQ query that returns customers with related orders.
Dim customerQuery = From cust In context.Customers.Expand("Orders") _
Where cust.Country = customerCountry _
Select cust
' Create a new collection for binding based on the LINQ query.
trackedCustomers = New DataServiceCollection(Of Customer)(customerQuery, _
TrackingMode.AutoChangeTracking, "Customers", _
AddressOf OnMyPropertyChanged, AddressOf OnMyCollectionChanged)
' Bind the root StackPanel element to the collection
' related object binding paths are defined in the XAML.
Me.LayoutRoot.DataContext = trackedCustomers
Catch ex As DataServiceQueryException
MessageBox.Show("The query could not be completed:\n" + ex.ToString())
Catch ex As InvalidOperationException
MessageBox.Show("The following error occurred:\n" + ex.ToString())
End Try
End Sub
' Method that is called when the CollectionChanged event is handled.
Private Function OnMyCollectionChanged( _
ByVal entityCollectionChangedinfo As EntityCollectionChangedParams) As Boolean
If entityCollectionChangedinfo.Action = _
NotifyCollectionChangedAction.Remove Then
' Delete the related items when an order is deleted.
If entityCollectionChangedinfo.TargetEntity.GetType() Is GetType(Order) Then
' Get the context and object from the supplied parameter.
Dim context = entityCollectionChangedinfo.Context
Dim deletedOrder As Order = _
CType(entityCollectionChangedinfo.TargetEntity, Order)
If deletedOrder.Order_Details.Count = 0 Then
' Load the related OrderDetails.
context.LoadProperty(deletedOrder, "Order_Details")
End If
' Delete the order and its related items
For Each item As Order_Detail In deletedOrder.Order_Details
context.DeleteObject(item)
Next
' Delete the order and then return false since the object is already deleted.
context.DeleteObject(deletedOrder)
Return True
Else
Return False
End If
Else
' Use the default behavior.
Return False
End If
End Function
' Method that is called when the PropertyChanged event is handled.
Private Function OnMyPropertyChanged( _
ByVal entityChangedInfo As EntityChangedParams) As Boolean
' Validate a changed order to ensure that changes are not made
' after the order ships.
If entityChangedInfo.Entity.GetType() Is GetType(Order) AndAlso _
(CType(entityChangedInfo.Entity, Order).ShippedDate < DateTime.Today) Then
Throw New ApplicationException(String.Format( _
"The order {0} cannot be changed because it shipped on {1}.", _
CType(entityChangedInfo.Entity, Order).OrderID, _
CType(entityChangedInfo.Entity, Order).ShippedDate))
Return False
Else
Return True
End If
End Function
Private Sub deleteButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
' Get the Orders binding collection.
If customerIDComboBox.SelectedItem IsNot Nothing Then
Dim trackedOrders As DataServiceCollection(Of Order) = _
(CType(customerIDComboBox.SelectedItem, Customer)).Orders
' Remove the currently selected order.
trackedOrders.Remove(CType(ordersDataGrid.SelectedItem, Order))
End If
End Sub
Private Sub saveChangesButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
Try
' Save changes to the data service.
context.SaveChanges()
Catch ex As Exception
MessageBox.Show(ex.ToString())
End Try
End Sub
End Class
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Data.Services.Client;
using NorthwindClient.Northwind;
using System.Collections.Specialized;
namespace NorthwindClient
{
public partial class CustomerOrdersCustom : Window
{
private NorthwindEntities context;
private DataServiceCollection<Customer> trackedCustomers;
private const string customerCountry = "Germany";
private const string svcUri = "https://localhost:12345/Northwind.svc/";
public CustomerOrdersCustom()
{
InitializeComponent();
}
private void Window_Loaded(object sender, RoutedEventArgs e)
{
try
{
// Initialize the context for the data service.
context = new NorthwindEntities(new Uri(svcUri));
// Create a LINQ query that returns customers with related orders.
var customerQuery = from cust in context.Customers.Expand("Orders")
where cust.Country == customerCountry
select cust;
// Create a new collection for binding based on the LINQ query.
trackedCustomers = new DataServiceCollection<Customer>(customerQuery,
TrackingMode.AutoChangeTracking,"Customers",
OnPropertyChanged, OnCollectionChanged);
// Bind the root StackPanel element to the collection;
// related object binding paths are defined in the XAML.
this.LayoutRoot.DataContext = trackedCustomers;
}
catch (DataServiceQueryException ex)
{
MessageBox.Show("The query could not be completed:\n" + ex.ToString());
}
catch (InvalidOperationException ex)
{
MessageBox.Show("The following error occurred:\n" + ex.ToString());
}
}
// Method that is called when the CollectionChanged event is handled.
private bool OnCollectionChanged(
EntityCollectionChangedParams entityCollectionChangedinfo)
{
if (entityCollectionChangedinfo.Action ==
NotifyCollectionChangedAction.Remove)
{
// Delete the related items when an order is deleted.
if (entityCollectionChangedinfo.TargetEntity.GetType() == typeof(Order))
{
// Get the context and object from the supplied parameter.
DataServiceContext context = entityCollectionChangedinfo.Context;
Order deletedOrder = entityCollectionChangedinfo.TargetEntity as Order;
if (deletedOrder.Order_Details.Count == 0)
{
// Load the related OrderDetails.
context.LoadProperty(deletedOrder, "Order_Details");
}
// Delete the order and its related items;
foreach (Order_Detail item in deletedOrder.Order_Details)
{
context.DeleteObject(item);
}
// Delete the order and then return true since the object is already deleted.
context.DeleteObject(deletedOrder);
return true;
}
else
{
return false;
}
}
else
{
// Use the default behavior.
return false;
}
}
// Method that is called when the PropertyChanged event is handled.
private bool OnPropertyChanged(EntityChangedParams entityChangedInfo)
{
// Validate a changed order to ensure that changes are not made
// after the order ships.
if ((entityChangedInfo.Entity.GetType() == typeof(Order)) &&
((Order)(entityChangedInfo.Entity)).ShippedDate < DateTime.Today)
{
throw new ApplicationException(string.Format(
"The order {0} cannot be changed because it shipped on {1}.",
((Order)(entityChangedInfo.Entity)).OrderID,
((Order)(entityChangedInfo.Entity)).ShippedDate));
}
return false;
}
private void deleteButton_Click(object sender, RoutedEventArgs e)
{
if (customerIDComboBox.SelectedItem != null)
{
// Get the Orders binding collection.
DataServiceCollection<Order> trackedOrders =
((Customer)(customerIDComboBox.SelectedItem)).Orders;
// Remove the currently selected order.
trackedOrders.Remove((Order)(ordersDataGrid.SelectedItem));
}
}
private void saveChangesButton_Click(object sender, RoutedEventArgs e)
{
try
{
// Save changes to the data service.
context.SaveChanges();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
}
}
다음 XAML에서는 이전 예제의 창을 정의합니다.
<Window x:Class="CustomerOrdersCustom"
xmlns="https://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="https://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="https://schemas.openxmlformats.org/markup-compatibility/2006"
Height="423" Width="679" Loaded="Window_Loaded" >
<StackPanel Orientation="Vertical" Height="Auto" Name="LayoutRoot" Width="Auto">
<Label Content="Customer ID" Margin="20,0,0,0" />
<ComboBox Name="customerIDComboBox" DisplayMemberPath="CustomerID" ItemsSource="{Binding}"
IsSynchronizedWithCurrentItem="True" SelectedIndex="0" Height="23" Width="120"
HorizontalAlignment="Left" Margin="20,0,0,0" VerticalAlignment="Center" />
<ListView ItemsSource="{Binding Path=Orders}" Name="ordersDataGrid" Margin="34,46,34,50">
<ListView.View>
<GridView AllowsColumnReorder="False" ColumnHeaderToolTip="Line Items">
<GridViewColumn DisplayMemberBinding="{Binding Path=OrderID, Mode=OneWay}"
Header="Order ID" Width="50"/>
<GridViewColumn DisplayMemberBinding="{Binding Path=OrderDate, Mode=TwoWay}"
Header="Order Date" Width="50"/>
<GridViewColumn DisplayMemberBinding="{Binding Path=Freight, Mode=TwoWay}"
Header="Freight Cost" Width="50"/>
</GridView>
</ListView.View>
</ListView>
<StackPanel Orientation="Horizontal">
<Button Name="deleteButton" Content="Delete Order" Click="deleteButton_Click"
Width="80" Height="30" Margin="450,0,10,0"/>
<Button Name="saveChangesButton" Content="Save Changes" Click="saveChangesButton_Click"
Width="80" Height="30" Margin="10,0,0,0"/>
</StackPanel>
</StackPanel>
</Window>