EntityCollectionChangedParams Class
Encapsulates the arguments of a CollectionChanged delegate.
Assembly: System.Data.Services.Client (in System.Data.Services.Client.dll)
The EntityCollectionChangedParams type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | Action | A NotifyCollectionChangedAction value that indicates how the collection was changed. |
![]() | Collection | The DataServiceCollection<T> that has changed. |
![]() | Context | The DataServiceContext associated with the DataServiceCollection<T> that has changed. |
![]() | PropertyName | The navigation property on the source object that references the collection that has changed. |
![]() | SourceEntity | The source object that references the target object in the collection by using a navigation property. |
![]() | SourceEntitySet | The entity set of the source object. |
![]() | TargetEntity | The entity object in the collection that has changed. |
![]() | TargetEntitySet | The entity set name of the object in the collection. |
| Name | Description | |
|---|---|---|
![]() | Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
![]() | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
![]() | GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
The following code-behind page for the XAML file creates a DataServiceCollection<T> with custom methods that are called when changes occur to data that is bound to the binding collection. When the CollectionChanged event occurs, the supplied method prevents an item that has been removed from the binding collection from being deleted from the data service. When the PropertyChanged event occurs, the ShipDate value is validated to ensure that changes are not made to orders that have already shipped.
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 = "http://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
The following XAML code defines the window for the previous example.
<Window x:Class="CustomerOrdersCustom" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://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>
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
