[英]MVVM Treeview selected item
I hope someone is willing to help me out here. 我希望有人愿意在这里帮助我。 I`m pretty new to MVVM, an after reading manny post and examples i still cant figure this out. 我是MVVM的新手,在阅读了很多帖子和示例之后,我仍然无法弄清这一点。
i have EF database filled with items and calculations that belong to each Item. 我的EF数据库中充满了项目和属于每个项目的计算。 i`m showing the items and calculations using a treeview and HierarchicalDataTemplate. 我使用Treeview和HierarchicalDataTemplate显示项目和计算。 when i click on a treeview item, i want to bind the text of a label to be set at 当我单击树视图项目时,我想绑定要设置在的标签文本
public string totaalPrijs
but i just cant figure out how to do that! 但我只是不知道该怎么做!
this is how my CalculationViewModel looks 这是我的CalculationViewModel的样子
namespace Treeview_test1.ViewModel
{
public class CalculationViewModel : ViewModelBase
{
public CalculationViewModel(TableItemChildren child)
{
this.Child = child;
IsChecked = false;
}
public TableItemChildren Child { get; protected set; }
public string totaalPrijs
{
get { return Child.dbTotaalPrijs; }
set
{
if (Child.dbTotaalPrijs != value)
{
Child.dbTotaalPrijs = value;
RaisePropertyChanged("totaalPrijs");
}
}
}
private bool _isChecked;
public bool IsChecked
{
get { return _isChecked; }
set
{
if (_isChecked != value)
{
_isChecked = value;
RaisePropertyChanged("IsChecked");
}
}
}
}
and here is my ItemViewModel 这是我的ItemViewModel
namespace Treeview_test1.ViewModel
{
public class ItemViewModel : ViewModelBase
{
public ItemViewModel()
{
calcVMColl = new ObservableCollection<CalculationViewModel>();
foreach (TableItemChildren calc in Service.getItemCalculations("1"))
{
calcVMColl.Add(new CalculationViewModel(calc));
}
}
// Switch between real and mock data
private IGetCalculations _service;
public IGetCalculations Service
{
get
{
if (_service == null)
{
if (IsInDesignMode)
_service = new MockCalculations();
else
_service = new GetCalculations();
}
return _service;
}
set
{
_service = value;
}
}
private ObservableCollection<CalculationViewModel> _calcVMColl;
public ObservableCollection<CalculationViewModel> calcVMColl
{
get { return _calcVMColl; }
set
{
if (calcVMColl != value)
{
_calcVMColl = value;
RaisePropertyChanged("calcVMColl");
}
}
}
}
and XAML 和XAML
<Window x:Class="Treeview_test1.MainWindow" xmlns="http://schemas.microsoft.com/ winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525" xmlns:ViewModel="clr-namespace:Treeview_test1.ViewModel">
<Window.DataContext>
<ViewModel:ItemViewModel />
</Window.DataContext>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="204" />
<ColumnDefinition />
</Grid.ColumnDefinitions>
<TreeView x:Name="tree" Width="195" HorizontalAlignment="Left" ItemsSource="{Binding calcVMColl}" Background="LightGray" Grid.Column="0" RenderTransformOrigin="1.016,0.509">
<TreeView.ItemContainerStyle>
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="IsSelected" Value="{Binding IsChecked, Mode=TwoWay}" />
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="FontSize" Value="10" />
</Trigger>
</Style.Triggers>
</Style>
</TreeView.ItemContainerStyle>
<TreeView.Resources>
<DataTemplate DataType="{x:Type ViewModel:CalculationViewModel}">
<Label Content="{Binding totaalPrijs}" />
</DataTemplate>
</TreeView.Resources>
</TreeView>
<Label Grid.Column="1" HorizontalAlignment="Left" Margin="39,39,0,0" VerticalAlignment="Top" Content="{Binding....?}" Foreground="Black" FontFamily="segeo ui" FontSize="20" />
</Grid>
So in short: How do i bind the text of my label to the current selected treeview item? 简而言之:如何将标签的文本绑定到当前选定的树视图项目?
thanks in advance 提前致谢
Addy 阿迪
Binding the SelectedItem
of a TreeView
to a Label
(or TextBlock
) is fairly simple: 将TreeView
的SelectedItem
绑定到Label
(或TextBlock
)非常简单:
<TreeView Name="myTreeview"/>
<TextBlock Text="{Binding SelectedItem, ElementName=myTreeview, Mode=OneWay}"/>
However this won't actually display what you want, since the SelectedItem
of the TreeView
is typically an Object
and you need a string
to display in the TextBlock
. 但是,这实际上不会显示您想要的内容,因为TreeView
的SelectedItem
通常是一个Object
并且您需要一个string
才能在TextBlock
显示。
One way to handle this is to use a Converter
on the binding. 一种解决方法是在绑定上使用Converter
。 You can implement IValueConverter
and have it return the needed string from the SelectedItem
. 您可以实现IValueConverter
并使它从SelectedItem
返回所需的字符串。
class GetTextFromItemConverter : IValueConverter
{
object IValueConverter.Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
TreeViewItem itm = (TreeViewItem)value;
string myString = null;
//Retrieve whatever portion of the TreeViewItem you want to put in myString.
return myString;
}
object IValueConverter.ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
Then the binding on your TextBlock
will look like this: 然后,您的TextBlock
上的绑定将如下所示:
<TextBlock Text="{Binding SelectedItem, Converter={StaticResource GetTextFromItemConverter}, ElementName=myTreeview, Mode=OneWay}"/>
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