EntityCollectionChangedParams Classe
Definição
Encapsula os argumentos de um delegado CollectionChanged.Encapsulates the arguments of a CollectionChanged delegate.
public ref class EntityCollectionChangedParams sealed
public sealed class EntityCollectionChangedParams
type EntityCollectionChangedParams = class
Public NotInheritable Class EntityCollectionChangedParams
- Herança
-
EntityCollectionChangedParams
Exemplos
A seguinte página code-behind do arquivo XAML cria um DataServiceCollection<T> com métodos personalizados que são chamados quando ocorrem alterações nos dados associados à coleção de associação.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. Quando o CollectionChanged evento ocorre, o método fornecido impede que um item que foi removido da coleção de associação seja excluído do serviço de dados.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. Quando o PropertyChanged evento ocorre, o ShipDate valor é validado para garantir que as alterações não sejam feitas em pedidos que já foram enviados.When the PropertyChanged event occurs, the ShipDate value is validated to ensure that changes are not made to orders that have already shipped.
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 = "http://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());
}
}
}
}
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
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.NorthwindModel
Imports System.Collections.Specialized
Partial Public Class CustomerOrdersCustom
Inherits Window
Private context As NorthwindEntities
Private trackedCustomers As DataServiceCollection(Of Customers)
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 Customers)(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
Me.LayoutRoot.UpdateLayout()
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(Orders) Then
' Get the context and object from the supplied parameter.
Dim context = entityCollectionChangedinfo.Context
Dim deletedOrder As Orders = _
CType(entityCollectionChangedinfo.TargetEntity, Orders)
' Load the related OrderDetails.
context.LoadProperty(deletedOrder, "Order_Details")
' Delete the order and its related items
For Each item As Order_Details In deletedOrder.Order_Details
'context.DeleteLink(deletedOrder, "Order_Details", item)
context.DeleteObject(item)
Next
' Delete the order and then return false since the object is already deleted.
context.DeleteObject(deletedOrder)
Return False
Else
Return True
End If
Else
' Use the default behavior.
Return True
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(Orders) AndAlso _
(CType(entityChangedInfo.Entity, Orders).ShippedDate < DateTime.Today) Then
Throw New ApplicationException(String.Format( _
"The order {0} cannot be changed because it shipped on {1}.", _
CType(entityChangedInfo.Entity, Orders).OrderID, _
CType(entityChangedInfo.Entity, Orders).ShippedDate))
Return True
End If
End Function
Private Sub deleteButton_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
' Get the Orders binding collection.
Dim trackedOrders As DataServiceCollection(Of Orders) = _
(CType(customerIDComboBox.SelectedItem, Customers)).Orders
' Remove the currently selected order.
trackedOrders.Remove(CType(ordersDataGrid.SelectedItem, Orders))
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
O código XAML a seguir define a janela do exemplo anterior.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>
Propriedades
| Action |
Um valor NotifyCollectionChangedAction que indica como a coleção foi alterada.A NotifyCollectionChangedAction value that indicates how the collection was changed. |
| Collection |
O DataServiceCollection<T> que foi alterado.The DataServiceCollection<T> that has changed. |
| Context |
O DataServiceContext associado ao DataServiceCollection<T> que foi alterado.The DataServiceContext associated with the DataServiceCollection<T> that has changed. |
| PropertyName |
A propriedade de navegação no objeto de origem que faz referência à coleção que foi alterada.The navigation property on the source object that references the collection that has changed. |
| SourceEntity |
O objeto de origem que faz referência ao objeto de destino na coleção usando uma propriedade de navegação.The source object that references the target object in the collection by using a navigation property. |
| SourceEntitySet |
O conjunto de entidades do objeto de origem.The entity set of the source object. |
| TargetEntity |
O objeto de entidade da coleção que foi alterada.The entity object in the collection that has changed. |
| TargetEntitySet |
O nome do conjunto de entidades do objeto na coleção.The entity set name of the object in the collection. |
Métodos
| Equals(Object) |
Determina se o objeto especificado é igual ao objeto atual.Determines whether the specified object is equal to the current object. (Herdado de Object) |
| GetHashCode() |
Serve como a função de hash padrão.Serves as the default hash function. (Herdado de Object) |
| GetType() |
Obtém o Type da instância atual.Gets the Type of the current instance. (Herdado de Object) |
| MemberwiseClone() |
Cria uma cópia superficial do Object atual.Creates a shallow copy of the current Object. (Herdado de Object) |
| ToString() |
Retorna uma cadeia de caracteres que representa o objeto atual.Returns a string that represents the current object. (Herdado de Object) |