Binding to CurrentItem in a ItemsControl
The XAML below is basically trying to make a list of Button
s (rendered from the Name
property of objects in the Views
collection in the current DataContext
.
When I click on a button the CurrentItem
property of CollectionViewSource
should change and the associated View
should be displayed in a content presenter.
OK. If I click in the ListBox
in the XAML below it works exactly as desired.
But, If I click a button in the UniformGrid
(created by the items control) the CurrentItem
property is not updated.
How do I get the CurrentItem
to be updated when an item is selected in the ItemsControl
?
Thanks
<UserControl x:Class="Pos.Features.Reservation.ReservationView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:product="clr-namespace:Pos.Features.ProductBrowser"
xmlns:activity="clr-namespace:Pos.Features.ActivityBrowser"
xmlns:addbysku="clr-namespace:Pos.Features.AddBySku"
xmlns:client="clr-namespace:Pos.Features.ClientBrowser"
xmlns:notes="clr-namespace:Pos.Features.Notes"
xmlns:controls="clr-namespace:Pos.Views"
xmlns:res="clr-namespace:Pos.Core;assembly=Pos.Core"
Height="300" Width="300">
<UserControl.Resources>
<DataTemplate DataType="{x:Type product:ProductBrowserViewModel}">
<product:ProductBrowserView/>
</DataTemplate>
<DataTemplate DataType="{x:Type activity:ActivityBrowserViewModel}">
<activity:ActivityBrowserView/>
</DataTemplate>
<CollectionViewSource x:Name="x" x:Key="ViewsCollection" Source="{Binding Views}" />
</UserControl.Resources>
<StackPanel>
<ListBox Name="ListBoxMenu" Grid.Column="0" Margin="5" ItemsSource="{Binding Source={StaticResource ViewsCollection}}">
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding Name}" Padding="10"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
<ContentControl Grid.Column="1" Content="{Binding ElementName=ListBoxMenu, Path=SelectedItem}"/>
<ItemsControl Grid.Column="2" Name="ViewList" ItemsSource="{Binding Source={StaticResource ViewsCollection}}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button>
<TextBlock Text="{Binding Path=Name}" Name="txtButtonLabel" VerticalAlignment="Center" HorizontalAlignment="Center" Foreground="Black"/>
</Button>
</DataTemplate>
</ItemsControl.ItemTemplate>
开发者_如何学Go <ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<UniformGrid Rows="1" Columns="{Binding Views.Count}"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
</ItemsControl>
<ContentControl Grid.Column="3" Content="{Binding Source={StaticResource ViewsCollection}, Path=CurrentItem}"/>
<Button Grid.Column="4" Click="Button_Click">dsadsd</Button>
</StackPanel>
</UserControl>
Your button does nothing. Usually your ViewModel would have an ICommand called Select (or something similar) that the Button would be bound against
Command="{Binding Select, ElementName="root"}"
and you'd pass the instance to the ICommand that you'd like to select
CommandParameter="{Binding}"
It would look something like this (c#/XAML like pseudocode):
public class MyModel { public string Name {get;set;} }
public class MyViewModel
{
public ObservableCollection<MyModel> Models {get;set;}
public ICommand Select {get;set;}
/* configure Models and Select etc */
}
<UserControl DataContext="{StaticResource MyViewModelInstance}" x:Name="root">
<ItemsControl ItemsSource="{Binding Models}">
<ItemsControl.ItemTemplate>
<ItemsPanelTemplate>
<Button Text="{Binding Name}"
Command="{Binding Select, ElementName="root"}"
CommandParameter="{Binding}"/>
</ItemsPanelTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</UserControl>
The ItemsControl binds to Models, so each MyModel in Models gets a button. The button text is bound to the property Name. The button command is bound to the Select property in the ViewModel. When the button is pressed, it calls the ICommand, sending in the instance of MyModel that the button is bound against.
Please do note that using ViewModels within a UserControl
is a code smell. UserControl
s should appear to users as all other controls--they should have bindable public properties which are bound to the user's ViewModel, not yours. You then bind to the values of these properties within the UserControl
. For this example, you would have an ItemsSource property defined on your UserControl
, and the ItemsControl
would bind to this property rather than a ViewModel directly.
I think you have to do it manually in code-behind.
XAML
<Button Click="ViewListButton_Click">
<TextBlock Text="{Binding Path=Name}" Name="txtButtonLabel" VerticalAlignment="Center" HorizontalAlignment="Center" Foreground="Black"/>
</Button>
Code-behind
private void ViewListButton_Click(object sender, RoutedEventArgs e)
{
Button button = sender as Button;
ICollectionView view = CollectionViewSource.GetDefaultView(ViewList.ItemsSource);
view.MoveCurrentTo(button.DataContext);
}
If you're using the MVVM pattern and/or you don't want to use code-behind, you could bind the button's Command
to a command in your ViewModel, as suggested by Will
精彩评论