IEditableCollectionViewAddNewItem Интерфейс
Определение
Важно!
Некоторые сведения относятся к предварительной версии продукта, в которую до выпуска могут быть внесены существенные изменения. Майкрософт не предоставляет никаких гарантий, явных или подразумеваемых, относительно приведенных здесь сведений.
Определяет методы и свойства, реализуемые классом CollectionView для обеспечения задания добавления элементов указанного типа.
public interface class IEditableCollectionViewAddNewItem : System::ComponentModel::IEditableCollectionViewpublic interface IEditableCollectionViewAddNewItem : System.ComponentModel.IEditableCollectionViewtype IEditableCollectionViewAddNewItem = interface
interface IEditableCollectionViewPublic Interface IEditableCollectionViewAddNewItem
Implements IEditableCollectionView- Производный
- Реализации
Примеры
В следующем примере пользователь может добавлять различные типы элементов в коллекцию. Пользователь может ввести новый элемент и отправить запись или отменить транзакцию. Пример получает IEditableCollectionViewAddNewItem из Items свойства ListBox объекта и создает объект , тип которого определяется пользователем. Затем в примере вызывается AddNewItem метод для добавления объекта в коллекцию.
using System;
using System.ComponentModel;
using System.Windows;
namespace IEditableCollectionViewAddItemExample
{
public partial class Window1 : Window
{
public Window1()
{
InitializeComponent();
}
private void Button_Click(object sender, RoutedEventArgs e)
{
IEditableCollectionViewAddNewItem viewToAddDisparateItems =
catalogList.Items as IEditableCollectionViewAddNewItem;
if (!viewToAddDisparateItems.CanAddNewItem)
{
MessageBox.Show("You cannot add items to the list.");
return;
}
// Create a window that prompts the user to enter a new
// item to sell.
AddItemWindow win = new AddItemWindow();
// Create an item, depending on which RadioButton is selected.
// Radio buttons correspond to book, cd, dvd, or other.
LibraryItem newItem;
if ((bool)book.IsChecked)
{
newItem = new Book("Enter the book title", "Enter an Author", "Enter a Genre",
"Enter a call number", DateTime.Now + new TimeSpan(21, 0, 0, 0));
}
else if ((bool)cd.IsChecked)
{
newItem = new MusicCD("Enter the Album", "Enter the artist", 0, "CD.******",
DateTime.Now + new TimeSpan(14, 0, 0, 0));
}
else if ((bool)dvd.IsChecked)
{
newItem = new MovieDVD("Enter the movie title", "Enter the director",
"Enter the genre", new TimeSpan(), "DVD.******",
DateTime.Now + new TimeSpan(7, 0, 0, 0));
}
else
{
newItem = new LibraryItem("Enter the title", "Enter the call number",
DateTime.Now + new TimeSpan(14, 0, 0, 0));
}
// Add the new item to the collection by calling
// IEditableCollectionViewAddNewItem.AddNewItem.
// Set the DataContext of the AddItemWindow to the
// returned item.
win.DataContext = viewToAddDisparateItems.AddNewItem(newItem);
// If the user submits the new item, commit the new
// object to the collection. If the user cancels
// adding the new item, discard the new item.
if ((bool)win.ShowDialog())
{
viewToAddDisparateItems.CommitNew();
}
else
{
viewToAddDisparateItems.CancelNew();
}
}
}
}
Imports System.ComponentModel
Imports System.Windows
Partial Class Window1
Public Sub New()
InitializeComponent()
End Sub
Private Sub Button_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
Dim viewToAddDisparateItems As IEditableCollectionViewAddNewItem =
TryCast(catalogList.Items, IEditableCollectionViewAddNewItem)
If Not viewToAddDisparateItems.CanAddNewItem Then
MessageBox.Show("You cannot add items to the list.")
Exit Sub
End If
' Create a window that prompts the user to enter a new
' item to sell.
Dim win As New AddItemWindow()
' Create an item, depending on which RadioButton is selected.
' Radio buttons correspond to book, cd, dvd, or other.
Dim newItem As LibraryItem
If CBool(Book.IsChecked) Then
newItem = New Book("Enter the book title", "Enter an Author",
"Enter a Genre", "Enter a call number",
DateTime.Now + New TimeSpan(21, 0, 0, 0))
ElseIf CBool(cd.IsChecked) Then
newItem = New MusicCD("Enter the Album", "Enter the artist",
0, "CD.******", DateTime.Now + New TimeSpan(14, 0, 0, 0))
ElseIf CBool(dvd.IsChecked) Then
newItem = New MovieDVD("Enter the movie title",
"Enter the director", "Enter the genre", New TimeSpan(),
"DVD.******", DateTime.Now + New TimeSpan(7, 0, 0, 0))
Else
newItem = New LibraryItem("Enter the title",
"Enter the call number",
DateTime.Now + New TimeSpan(14, 0, 0, 0))
End If
' Add the new item to the collection by calling
' IEditableCollectionViewAddNewItem.AddNewItem.
' Set the DataContext of the AddItemWindow to the
' returned item.
win.DataContext = viewToAddDisparateItems.AddNewItem(newItem)
' If the user submits the new item, commit the new
' object to the collection. If the user cancels
' adding the new item, discard the new item.
If CBool(win.ShowDialog()) Then
viewToAddDisparateItems.CommitNew()
Else
viewToAddDisparateItems.CancelNew()
End If
End Sub
End Class
В следующем примере создается пользовательский интерфейс для предыдущего примера.
<StackPanel xmlns:src="clr-namespace:IEditableCollectionViewAddItemExample">
<StackPanel.Resources>
<src:LibraryCatalog x:Key="catalog"/>
<!--Use AlternationConverter to create alternating background brushes
to better distinguish each item. See AlternationConverter
for more information.-->
<AlternationConverter x:Key="BackgroundConverter">
<SolidColorBrush>LightBlue</SolidColorBrush>
<SolidColorBrush>LightGray</SolidColorBrush>
</AlternationConverter>
<!--The DataTemplate for LibraryItem, which is the base class
of the other data types.-->
<DataTemplate DataType="{x:Type src:LibraryItem}">
<StackPanel>
<TextBlock FontWeight="Bold">Item:</TextBlock>
<TextBlock Text="{Binding Title, StringFormat={}Title: {0}}"/>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Due Date: {0:d} Call Number: {1}">
<Binding Path="DueDate"/>
<Binding Path="CallNumber"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
</StackPanel>
</DataTemplate>
<!--The DataTemplate for Book.-->
<DataTemplate DataType="{x:Type src:Book}">
<StackPanel>
<TextBlock FontWeight="Bold">Book:</TextBlock>
<TextBlock Text="{Binding Title, StringFormat={}Title: {0}}"/>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Author: {0} Genre: {1}">
<Binding Path="Author"/>
<Binding Path="Genre"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Due Date: {0:d} Call Number: {1}">
<Binding Path="DueDate"/>
<Binding Path="CallNumber"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
</StackPanel>
</DataTemplate>
<!--The DataTemplate for MusicCD.-->
<DataTemplate DataType="{x:Type src:MusicCD}">
<StackPanel>
<TextBlock FontWeight="Bold">Music CD:</TextBlock>
<TextBlock Text="{Binding Title, StringFormat={}Title: {0}}"/>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Artist: {0} Tracks: {1}">
<Binding Path="Artist"/>
<Binding Path="NumberOfTracks"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Due Date: {0:d} Call Number: {1}">
<Binding Path="DueDate"/>
<Binding Path="CallNumber"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
</StackPanel>
</DataTemplate>
<!--The DataTemplate for MovieDVD-->
<DataTemplate DataType="{x:Type src:MovieDVD}">
<StackPanel>
<TextBlock FontWeight="Bold">Movie DVD:</TextBlock>
<TextBlock Text="{Binding Title, StringFormat={}Title: {0}}"/>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Director: {0} Genre: {1} Length: {2}">
<Binding Path="Director"/>
<Binding Path="Genre"/>
<Binding Path="Length"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
<TextBlock>
<TextBlock.Text>
<MultiBinding StringFormat="{}Due Date: {0:d} Call Number: {1}">
<Binding Path="DueDate"/>
<Binding Path="CallNumber"/>
</MultiBinding>
</TextBlock.Text>
</TextBlock>
</StackPanel>
</DataTemplate>
</StackPanel.Resources>
<!--Bind a ListBox to a collection of LibraryItem objects. The collection
can hold objects any type that inherits from LibraryItem.-->
<ListBox Name="catalogList" Height="350" AlternationCount="2"
ItemsSource="{StaticResource catalog}">
<!--Use alternating background styles to better distinguish each item.
See ItemsControl.AlternationIndex for more information.-->
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem">
<Setter Property="Background"
Value="{Binding RelativeSource={RelativeSource Self},
Path=(ItemsControl.AlternationIndex),
Converter={StaticResource BackgroundConverter}}"/>
<Setter Property="Margin" Value="3"/>
</Style>
</ListBox.ItemContainerStyle>
</ListBox>
<!--Enable the user to choose a type of item to add to the collection.-->
<TextBlock>Select an item to add:</TextBlock>
<RadioButton Name="book" >Book</RadioButton>
<RadioButton Name="cd">Music CD</RadioButton>
<RadioButton Name="dvd">DVD</RadioButton>
<RadioButton>Other</RadioButton>
<Button Margin="0,3,0,0" Click="Button_Click">Add Item</Button>
</StackPanel>
В следующем примере создается объект , AddItemWindow в который пользователь добавляет данные для нового элемента.
<StackPanel Margin="10" Width="250">
<StackPanel.Resources>
<!--Add an event handler to select all text when
a TextBox gets focus.-->
<Style TargetType="TextBox">
<EventSetter Event="GotFocus" Handler="TextBoxFocus"/>
</Style>
<!--Create a Template for HeaderedContentControl so the header is
to the left of the content.-->
<Style TargetType="HeaderedContentControl">
<Setter Property="Margin" Value="2"/>
<Setter Property="Focusable" Value="False"/>
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="HeaderedContentControl">
<DockPanel LastChildFill="False">
<ContentPresenter ContentSource="Header" DockPanel.Dock="Left"
Focusable="False" VerticalAlignment="Center"/>
<ContentPresenter ContentSource="Content" Margin="5,0,0,0"
DockPanel.Dock="Right" VerticalAlignment="Center"/>
</DockPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
<Style TargetType="Button">
<Setter Property="Width" Value="100"/>
<Setter Property="Margin" Value="10,15,15,15"/>
</Style>
<!--The DataTemplate that is used when the user
enters a new LibraryItem.-->
<DataTemplate DataType="{x:Type src:LibraryItem}">
<StackPanel>
<HeaderedContentControl Header="Title">
<TextBox Width="150" Text="{Binding Path=Title, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Due Date">
<TextBox Width="150" Text="{Binding Path=DueDate, StringFormat=d, Mode=TwoWay}">
</TextBox>
</HeaderedContentControl>
<HeaderedContentControl Header="Call Number">
<TextBox Width="150" Text="{Binding Path=CallNumber, Mode=TwoWay}"/>
</HeaderedContentControl>
</StackPanel>
</DataTemplate>
<!--The DataTemplate that is used when the user
enters a new Book.-->
<DataTemplate DataType="{x:Type src:Book}">
<StackPanel>
<HeaderedContentControl Header="Title">
<TextBox Width="150" Text="{Binding Path=Title, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Author">
<TextBox Width="150" Text="{Binding Path=Author, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Genre">
<TextBox Width="150" Text="{Binding Path=Genre, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Due Date">
<TextBox Width="150" Text="{Binding Path=DueDate, StringFormat=d, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Call Number">
<TextBox Width="150" Text="{Binding Path=CallNumber, Mode=TwoWay}"/>
</HeaderedContentControl>
</StackPanel>
</DataTemplate>
<!--The DataTemplate that is used when the user
enters a new MusicCD.-->
<DataTemplate DataType="{x:Type src:MusicCD}">
<StackPanel>
<HeaderedContentControl Header="Title">
<TextBox Width="150" Text="{Binding Path=Title, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Artist">
<TextBox Width="150" Text="{Binding Path=Artist, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Tracks">
<TextBox Width="150" Text="{Binding Path=NumberOfTracks, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Due Date">
<TextBox Width="150" Text="{Binding Path=DueDate, StringFormat=d, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Call Number">
<TextBox Width="150" Text="{Binding Path=CallNumber, Mode=TwoWay}"/>
</HeaderedContentControl>
</StackPanel>
</DataTemplate>
<!--The DataTemplate that is used when the user
enters a new MovieDVD.-->
<DataTemplate DataType="{x:Type src:MovieDVD}">
<StackPanel>
<HeaderedContentControl Header="Title">
<TextBox Width="150" Text="{Binding Path=Title, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Director">
<TextBox Width="150" Text="{Binding Path=Director, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Length">
<TextBox Width="150" Text="{Binding Path=Length, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Genre">
<TextBox Width="150" Text="{Binding Path=Genre, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Due Date">
<TextBox Width="150" Text="{Binding Path=DueDate, StringFormat=d, Mode=TwoWay}"/>
</HeaderedContentControl>
<HeaderedContentControl Header="Call Number">
<TextBox Width="150" Text="{Binding Path=CallNumber, Mode=TwoWay}"/>
</HeaderedContentControl>
</StackPanel>
</DataTemplate>
</StackPanel.Resources>
<!--One of the DataTemplates that defined above
is used by this ContentControl when the window is created.-->
<ContentControl Content="{Binding}" />
<StackPanel Orientation="Horizontal">
<Button IsDefault="True" Click="Submit_Click">_Submit</Button>
<Button IsCancel="True">_Cancel</Button>
</StackPanel>
</StackPanel>
В следующем примере показана логика элемента управления AddItemWindow.
using System.Windows;
using System.Windows.Controls;
namespace IEditableCollectionViewAddItemExample
{
public partial class AddItemWindow : Window
{
public AddItemWindow()
{
InitializeComponent();
}
private void Submit_Click(object sender, RoutedEventArgs e)
{
DialogResult = true;
Close();
}
// Select all text when the TextBox gets focus.
private void TextBoxFocus(object sender, RoutedEventArgs e)
{
TextBox tbx = sender as TextBox;
tbx.SelectAll();
}
}
}
Imports System.Windows
Imports System.Windows.Controls
Partial Public Class AddItemWindow
Inherits Window
Public Sub New()
InitializeComponent()
End Sub
Private Sub Submit_Click(ByVal sender As Object, ByVal e As RoutedEventArgs)
DialogResult = True
Close()
End Sub
' Select all text when the TextBox gets focus.
Private Sub TextBoxFocus(ByVal sender As Object, ByVal e As RoutedEventArgs)
Dim tbx As TextBox = TryCast(sender, TextBox)
tbx.SelectAll()
End Sub
End Class
В следующем примере показаны типы данных и коллекция, которые использовались в предыдущих примерах.
using System;
using System.Collections.ObjectModel;
using System.ComponentModel;
namespace IEditableCollectionViewAddItemExample
{
// LibraryItem implements INotifyPropertyChanged so that the
// application is notified when a property changes. It
// implements IEditableObject so that pending changes can be discarded.
public class LibraryItem : INotifyPropertyChanged, IEditableObject
{
struct ItemData
{
internal string Title;
internal string CallNumber;
internal DateTime DueDate;
}
ItemData copyData;
ItemData currentData;
public LibraryItem(string title, string callNum, DateTime dueDate)
{
Title = title;
CallNumber = callNum;
DueDate = dueDate;
}
public override string ToString()
{
return String.Format("{0}, {1:c}, {2:D}", Title, CallNumber, DueDate);
}
public string Title
{
get { return currentData.Title; }
set
{
if (currentData.Title != value)
{
currentData.Title = value;
NotifyPropertyChanged("Title");
}
}
}
public string CallNumber
{
get { return currentData.CallNumber; }
set
{
if (currentData.CallNumber != value)
{
currentData.CallNumber = value;
NotifyPropertyChanged("CallNumber");
}
}
}
public DateTime DueDate
{
get { return currentData.DueDate; }
set
{
if (value != currentData.DueDate)
{
currentData.DueDate = value;
NotifyPropertyChanged("DueDate");
}
}
}
#region INotifyPropertyChanged Members
public event PropertyChangedEventHandler PropertyChanged;
protected void NotifyPropertyChanged(String info)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(info));
}
}
#endregion
#region IEditableObject Members
public virtual void BeginEdit()
{
copyData = currentData;
}
public virtual void CancelEdit()
{
currentData = copyData;
NotifyPropertyChanged("");
}
public virtual void EndEdit()
{
copyData = new ItemData();
}
#endregion
}
public class MusicCD : LibraryItem
{
private struct MusicData
{
internal int SongNumber;
internal string Artist;
}
MusicData copyData;
MusicData currentData;
public MusicCD(string title, string artist, int songNum, string callNum, DateTime dueDate)
: base(title, callNum, dueDate)
{
currentData.SongNumber = songNum;
currentData.Artist = artist;
}
public string Artist
{
get { return currentData.Artist; }
set
{
if (value != currentData.Artist)
{
currentData.Artist = value;
NotifyPropertyChanged("Artist");
}
}
}
public int NumberOfTracks
{
get { return currentData.SongNumber; }
set
{
if (value != currentData.SongNumber)
{
currentData.SongNumber = value;
NotifyPropertyChanged("NumberOfTracks");
}
}
}
public override void BeginEdit()
{
base.BeginEdit();
copyData = currentData;
}
public override void CancelEdit()
{
base.CancelEdit();
currentData = copyData;
}
public override void EndEdit()
{
base.EndEdit();
copyData = new MusicData();
}
public override string ToString()
{
return string.Format(
"Album: {0}\nArtist: {1}\nTracks: {2}\nDue Date: {3:d}\nCall Number: {4}",
this.Title, this.Artist, this.NumberOfTracks, this.DueDate, this.CallNumber);
}
}
public class Book : LibraryItem
{
private struct BookData
{
internal string Author;
internal string Genre;
}
BookData currentData;
BookData copyData;
public Book(string title, string author, string genre, string callnum, DateTime dueDate)
: base (title, callnum, dueDate)
{
this.Author = author;
this.Genre = genre;
}
public string Author
{
get { return currentData.Author; }
set
{
if (value != currentData.Author)
{
currentData.Author = value;
NotifyPropertyChanged("Author");
}
}
}
public string Genre
{
get { return currentData.Genre; }
set
{
if (value != currentData.Genre)
{
currentData.Genre = value;
NotifyPropertyChanged("Genre");
}
}
}
public override void BeginEdit()
{
base.BeginEdit();
copyData = currentData;
}
public override void CancelEdit()
{
base.CancelEdit();
currentData = copyData;
}
public override void EndEdit()
{
base.EndEdit();
copyData = new BookData();
}
public override string ToString()
{
return String.Format(
"Title: {0}\nAuthor: {1}\nGenre: {2}\nDue Date: {3:d}\nCall Number: {4}",
this.Title, this.Author, this.Genre, this.DueDate, this.CallNumber);
}
}
public class MovieDVD : LibraryItem
{
private struct MovieData
{
internal TimeSpan Length;
internal string Director;
internal string Genre;
}
private MovieData currentData;
private MovieData copyData;
public MovieDVD(string title, string director, string genre, TimeSpan length, string callnum, DateTime dueDate)
: base(title, callnum, dueDate)
{
this.Director = director;
this.Length = length;
this.Genre = genre;
}
public TimeSpan Length
{
get { return currentData.Length; }
set
{
if (value != currentData.Length)
{
currentData.Length = value;
NotifyPropertyChanged("Length");
}
}
}
public string Director
{
get { return currentData.Director; }
set
{
if (value != currentData.Director)
{
currentData.Director = value;
NotifyPropertyChanged("Director");
}
}
}
public string Genre
{
get { return currentData.Genre; }
set
{
if (value != currentData.Genre)
{
currentData.Genre = value;
NotifyPropertyChanged("Genre");
}
}
}
public override void BeginEdit()
{
base.BeginEdit();
copyData = currentData;
}
public override void CancelEdit()
{
base.CancelEdit();
currentData = copyData;
}
public override void EndEdit()
{
base.EndEdit();
copyData = new MovieData();
}
public override string ToString()
{
return String.Format("Title: {0}\nDirector: {1}\nGenre: {2}\nLength: {3}\nDue Date: {4:d}\nCall Number: {5}",
this.Title, this.Director, this.Genre, this.Length, this.DueDate, this.CallNumber);
}
}
public class LibraryCatalog : ObservableCollection<LibraryItem>
{
public LibraryCatalog()
{
Add(new MusicCD("A Programmers Plight", "Jon Orton",
12, "CD.OrtPro", new DateTime(2010, 3, 24)));
Add(new Book("Cooking with Thyme", "Eliot J. Graff",
"Home Economics", "HE.GraThy", new DateTime(2010, 2, 26)));
Add(new MovieDVD("Terror of the Testers", "Molly Dempsey",
"Horror", new TimeSpan(1, 27, 19), "DVD.DemTer",
new DateTime(2010, 2, 1)));
Add(new MusicCD("The Best of Jim Hance", "Jim Hance",
15, "CD.HanBes", new DateTime(2010, 1, 31)));
Add(new Book("Victor and the VB Vehicle", "Tommy Hortono",
"YA Fiction", "YA.HorVic", new DateTime(2010, 3, 1)));
}
}
}
Imports System.Collections.ObjectModel
Imports System.ComponentModel
' LibraryItem implements INotifyPropertyChanged so that the
' application is notified when a property changes. It
' implements IEditableObject so that pending changes can be discarded.
Public Class LibraryItem
Implements INotifyPropertyChanged
Implements IEditableObject
Private Structure ItemData
Friend Title As String
Friend CallNumber As String
Friend DueDate As DateTime
End Structure
Private copyData As ItemData
Private currentData As ItemData
Public Sub New(ByVal title As String, ByVal callNum As String, ByVal dueDate As DateTime)
Me.Title = title
Me.CallNumber = callNum
Me.DueDate = dueDate
End Sub
Public Property Title() As String
Get
Return currentData.Title
End Get
Set(ByVal value As String)
If currentData.Title <> value Then
currentData.Title = value
NotifyPropertyChanged("Title")
End If
End Set
End Property
Public Property CallNumber() As String
Get
Return currentData.CallNumber
End Get
Set(ByVal value As String)
If currentData.CallNumber <> value Then
currentData.CallNumber = value
NotifyPropertyChanged("CallNumber")
End If
End Set
End Property
Public Property DueDate() As DateTime
Get
Return currentData.DueDate
End Get
Set(ByVal value As DateTime)
If value <> currentData.DueDate Then
currentData.DueDate = value
NotifyPropertyChanged("DueDate")
End If
End Set
End Property
#Region "INotifyPropertyChanged Members"
Public Event PropertyChanged As PropertyChangedEventHandler _
Implements INotifyPropertyChanged.PropertyChanged
Protected Sub NotifyPropertyChanged(ByVal info As String)
RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(info))
End Sub
#End Region
#Region "IEditableObject Members"
Public Overridable Sub BeginEdit() Implements IEditableObject.BeginEdit
copyData = currentData
End Sub
Public Overridable Sub CancelEdit() Implements IEditableObject.CancelEdit
currentData = copyData
NotifyPropertyChanged("")
End Sub
Public Overridable Sub EndEdit() Implements IEditableObject.EndEdit
copyData = New ItemData()
End Sub
#End Region
End Class
Public Class MusicCD
Inherits LibraryItem
Private Structure MusicData
Friend SongNumber As Integer
Friend Artist As String
End Structure
Private copyData As MusicData
Private currentData As MusicData
Public Sub New(ByVal title As String, ByVal artist As String,
ByVal songNum As Integer, ByVal callNum As String,
ByVal dueDate As DateTime)
MyBase.New(title, callNum, dueDate)
currentData.SongNumber = songNum
currentData.Artist = artist
End Sub
Public Property Artist() As String
Get
Return currentData.Artist
End Get
Set(ByVal value As String)
If value <> currentData.Artist Then
currentData.Artist = value
NotifyPropertyChanged("Artist")
End If
End Set
End Property
Public Property NumberOfTracks() As Integer
Get
Return currentData.SongNumber
End Get
Set(ByVal value As Integer)
If value <> currentData.SongNumber Then
currentData.SongNumber = value
NotifyPropertyChanged("NumberOfTracks")
End If
End Set
End Property
Public Overloads Overrides Sub BeginEdit()
MyBase.BeginEdit()
copyData = currentData
End Sub
Public Overloads Overrides Sub CancelEdit()
MyBase.CancelEdit()
currentData = copyData
End Sub
Public Overloads Overrides Sub EndEdit()
MyBase.EndEdit()
copyData = New MusicData()
End Sub
End Class
Public Class Book
Inherits LibraryItem
Private Structure BookData
Friend Author As String
Friend Genre As String
End Structure
Private currentData As BookData
Private copyData As BookData
Public Sub New(ByVal title As String, ByVal author As String,
ByVal genre As String, ByVal callnum As String,
ByVal dueDate As DateTime)
MyBase.New(title, callnum, dueDate)
Me.Author = author
Me.Genre = genre
End Sub
Public Property Author() As String
Get
Return currentData.Author
End Get
Set(ByVal value As String)
If value <> currentData.Author Then
currentData.Author = value
NotifyPropertyChanged("Author")
End If
End Set
End Property
Public Property Genre() As String
Get
Return currentData.Genre
End Get
Set(ByVal value As String)
If value <> currentData.Genre Then
currentData.Genre = value
NotifyPropertyChanged("Genre")
End If
End Set
End Property
Public Overloads Overrides Sub BeginEdit()
MyBase.BeginEdit()
copyData = currentData
End Sub
Public Overloads Overrides Sub CancelEdit()
MyBase.CancelEdit()
currentData = copyData
End Sub
Public Overloads Overrides Sub EndEdit()
MyBase.EndEdit()
copyData = New BookData()
End Sub
End Class
Public Class MovieDVD
Inherits LibraryItem
Private Structure MovieData
Friend Length As TimeSpan
Friend Director As String
Friend Genre As String
End Structure
Private currentData As MovieData
Private copyData As MovieData
Public Sub New(ByVal title As String, ByVal director As String,
ByVal genre As String, ByVal length As TimeSpan,
ByVal callnum As String, ByVal dueDate As DateTime)
MyBase.New(title, callnum, dueDate)
Me.Director = director
Me.Length = length
Me.Genre = genre
End Sub
Public Property Length() As TimeSpan
Get
Return currentData.Length
End Get
Set(ByVal value As TimeSpan)
If value <> currentData.Length Then
currentData.Length = value
NotifyPropertyChanged("Length")
End If
End Set
End Property
Public Property Director() As String
Get
Return currentData.Director
End Get
Set(ByVal value As String)
If value <> currentData.Director Then
currentData.Director = value
NotifyPropertyChanged("Director")
End If
End Set
End Property
Public Property Genre() As String
Get
Return currentData.Genre
End Get
Set(ByVal value As String)
If value <> currentData.Genre Then
currentData.Genre = value
NotifyPropertyChanged("Genre")
End If
End Set
End Property
Public Overloads Overrides Sub BeginEdit()
MyBase.BeginEdit()
copyData = currentData
End Sub
Public Overloads Overrides Sub CancelEdit()
MyBase.CancelEdit()
currentData = copyData
End Sub
Public Overloads Overrides Sub EndEdit()
MyBase.EndEdit()
copyData = New MovieData()
End Sub
End Class
Public Class LibraryCatalog
Inherits ObservableCollection(Of LibraryItem)
Public Sub New()
Add(New MusicCD("A Programmers Plight", "Jon Orton", 12,
"CD.OrtPro", New DateTime(2010, 3, 24)))
Add(New Book("Cooking with Thyme", "Eliot J. Graff",
"Home Economics", "HE.GraThy", New DateTime(2010, 2, 26)))
Add(New MovieDVD("Terror of the Testers", "Molly Dempsey", "Horror",
New TimeSpan(1, 27, 19), "DVD.DemTer", New DateTime(2010, 2, 1)))
Add(New MusicCD("The Best of Jim Hance", "Jim Hance", 15,
"CD.HanBes", New DateTime(2010, 1, 31)))
Add(New Book("Victor and the VB Vehicle", "Tommy Hortono",
"YA Fiction", "YA.HorVic", New DateTime(2010, 3, 1)))
End Sub
End Class
Комментарии
Интерфейс IEditableCollectionViewAddNewItem позволяет разработчикам приложений указать, какой тип объекта следует добавить в коллекцию. Этот интерфейс расширяет IEditableCollectionView, что позволяет добавлять, изменять и удалять элементы в коллекции. IEditableCollectionViewAddNewItemAddNewItem добавляет метод , который принимает объект , добавляемый в коллекцию. Этот метод полезен, если коллекция и объекты, которые требуется добавить, имеют одну или несколько следующих характеристик:
Объекты в имеют CollectionView разные типы.
У объектов нет конструктора без параметров.
Объект уже существует.
Вы хотите добавить
nullобъект в коллекцию.
Свойства
| CanAddNew |
Возвращает значение, указывающее, можно ли добавить новый элемент в коллекцию. (Унаследовано от IEditableCollectionView) |
| CanAddNewItem |
Получает значение, указывающее, можно ли добавить указанный объект в коллекцию. |
| CanCancelEdit |
Возвращает значение, указывающее, может ли представление коллекции отклонить отложенные изменения и восстановить исходные значения изменяемого объекта. (Унаследовано от IEditableCollectionView) |
| CanRemove |
Возвращает значение, указывающее, можно ли удалить элемент из коллекции. (Унаследовано от IEditableCollectionView) |
| CurrentAddItem |
Возвращает элемент, добавляемый во время текущей транзакции добавления. (Унаследовано от IEditableCollectionView) |
| CurrentEditItem |
Возвращает изменяемый элемент коллекции. (Унаследовано от IEditableCollectionView) |
| IsAddingNew |
Возвращает значение, указывающее, выполняется ли в данный момент транзакция добавления. (Унаследовано от IEditableCollectionView) |
| IsEditingItem |
Возвращает значение, указывающее, выполняется ли в данный момент транзакция изменения. (Унаследовано от IEditableCollectionView) |
| NewItemPlaceholderPosition |
Возвращает или задает положение местозаполнителя нового элемента в представлении коллекции. (Унаследовано от IEditableCollectionView) |
Методы
| AddNew() |
Добавляет новый элемент в коллекцию. (Унаследовано от IEditableCollectionView) |
| AddNewItem(Object) |
Добавляет указанный объект в коллекцию. |
| CancelEdit() |
Завершает транзакцию изменения и, если это возможно, восстанавливает исходное значение для элемента. (Унаследовано от IEditableCollectionView) |
| CancelNew() |
Завершает транзакцию добавления и отменяет ожидающий новый элемент. (Унаследовано от IEditableCollectionView) |
| CommitEdit() |
Завершает транзакцию изменения и сохраняет отложенные изменения. (Унаследовано от IEditableCollectionView) |
| CommitNew() |
Завершает транзакцию добавления и сохраняет ожидаемый новый элемент. (Унаследовано от IEditableCollectionView) |
| EditItem(Object) |
Начинает транзакцию изменения заданного элемента. (Унаследовано от IEditableCollectionView) |
| Remove(Object) |
Удаляет заданный элемент из коллекции. (Унаследовано от IEditableCollectionView) |
| RemoveAt(Int32) |
Удаляет элемент в указанной позиции из коллекции. (Унаследовано от IEditableCollectionView) |
Применяется к
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