The first textbox below cannot find the parent TabItem however the second textbox can. What am I doing wrong in the first binding?
<TabItem Style="{StaticResource TabItemStyle}" x:Name="zzzzz">
<StackPanel >
<TextBlock Text="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type TabItem}}, Path=IsSelected}"></TextBlock>
<TextBlock Text="{Binding ElementName=zzzzz, Path=IsSelected}" />
</StackPanel>
</TabItem>
The error message is: System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.TabItem', AncestorLevel='1''. BindingExpression:Path=IsSelected; DataItem=null; target element is 'TextBlock' (Name=''); target property is 'Text' (type 'String')
I've never had to set AncestorLevel but I tried setting it to 5000 it still does not work.
Note that I am not setting the binding from the DataTemplate as is shown in this question.
The TabItem is not a visual ancestor of the TextBlock in the content panel of the TabControl so your first binding won't ever work.
If you put a TextBlock in the header of a TabItem, you can bind to the latter using a {RelativeSource}. But the currently visible content panel is a visual child of the TabContol itself rather than a specific TabItem.
Related
My WPF uses the MVVM approach. I'm trying to bind 2 controls within my list control
<ListBox ItemsSource="{Binding ParentDuplicate}" SelectedItem="{Binding SelectedParent, UpdateSourceTrigger=PropertyChanged}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel>
<ContentControl Content="{Binding}" />
<Button Content="Delete me now"
Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorLevel=1, AncestorType=Window}, Path=DeleteCommand}"
CommandParameter="{Binding FilePath}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
The problem I'm having, is the DeleteCommand is not binding (the Ouput window informs me as well)
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Data.Binding', AncestorLevel='1''. BindingExpression:Path=DeleteCommand; DataItem=null; target element is 'Button' (Name=''); target property is 'Command' (type 'ICommand')
If I move this button to outside the ListBox, then the binding works and the event fires so I know the issue must be with the ListBox (I'm guessing the problem is the ItemsSource prevents the binding to anything but the ItemsSource bound property (in this case, ParentDuplicate))
So, within the Button control, there are 2 properties being bound, DeleteCommand and FilePath
Both of these properties live within my single ViewModel. FilePath is a child of ParentDuplicate and this binds as desired. The issue is only with the DeleteCommand. What am I doing wrong?
Edit
When I use the Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorLevel=1, AncestorType=Window}, Path=DeleteCommand} it is looking in my MainWindow code behind, not at the ViewModel. How do I make it use the ViewModel?
I tried
Command="{Binding RelativeSource={RelativeSource AncestorType=xmlnsViewModel:MainWindowViewModel}, Path=DeleteCommand}"
but the above also results in the same binding errors
The ancestor search finds the control, not the DataContext, so you'll need to tell your binding where to find the DeleteCommand property. If your ViewModel is the DataContext of the MainWindow then you can just use:
<Button Content="Delete me now"
Command="{Binding RelativeSource={RelativeSource
Mode=FindAncestor, AncestorLevel=1, AncestorType=Window},
Path=DataContext.DeleteCommand}"
CommandParameter="{Binding FilePath}" />
I tried to bind a ToolTip text in a UserControl this way:
<Grid.ToolTip>
<TextBlock
Text="{
Binding Path=InfoTT,
RelativeSource={
RelativeSource Mode=FindAncestor,
AncestorType={x:Type UserControl}
}
}" />
</Grid.ToolTip>
And it doesn't work, the Tooltip was empty and in logs, I saw:
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.UserControl', AncestorLevel='1''. BindingExpression:Path=InfoTT; DataItem=null; target element is 'TextBlock' (Name=''); target property is 'Text' (type 'String')*
But when I did:
<Grid
ToolTip="{
Binding Path=InfoTT,
RelativeSource={
RelativeSource Mode=FindAncestor,
AncestorType={x:Type UserControl}
}
}">
</Grid>
It worked. Can anyone explain why the first way doesn't work?
When Binding.RelativeSource doesn't resolve, you can always be sure that the Binding.Target is not part of the visual tree.
In your first example you are explicitly defining the tree structure of the ToolTip. You are explicitly creating the content e.g. by adding the TextBlock. The content of the ToolTip is not part of the visual tree and therefore the Binding.RelativeSource can't be resolved.
In your second example, you let the FrameworkElement implicitly create the ToolTip content.
Now FrameWorkElement will first resolve the Binding, which resolves, as the FrameworkElement is still part of the visual tree. The resolved value is taken, ToString invoked, a TextBlock created and the string value assigned to TextBlock.Text.
Solution
To solve the binding problem, when implementing the ToolTip explicitly, you can implement a Binding Proxy as suggested in a comment by #Mark Feldman which makes use of the StaticResource markup to provide a Binding.Source to elements that are not part of the visual tree.
It's basically a bindable ObjectDataProvider.
A similar solution to the binding proxy is to define the content as a resource of the Grid and then reference it via DynamicResource using a ContentPresnter:
<UserControl>
<Grid>
<Grid.Resources>
<!-- The proxy -->
<TextBlock x:Key="ToolTipText"
Text="{Binding RelativeSource={RelativeSource AncestorType=UserControl}, Path=InfoTT}" />
<Grid.ToolTip>
<ToolTip>
<ContentPresenter Content="{DynamicResource ToolTipText}" />
</ToolTip>
</Grid.ToolTip>
</Grid>
</UserControl>
But you could also make use of the fact that the DataContext is still inherited. Bindings to the DataContext will still resolve.
In your scenario, where you want to bind the content of the ToolTip to a property of the parent UserControl, you could bind this property to a property of the view model, which is the current DataContext of Grid (and therefore for its ToolTip). I only recommend this, when binding to business data and not layout data:
<UserControl InfoTT="{Binding ViewModelInfoTT}">
<UserControl.DataContext>
<ViewModel />
</UserControl.DataContext>
<Grid>
<Grid.ToolTip>
<ToolTip>
<TextBlock Text="{Binding ViewModelInfoTT}" />
</ToolTip>
</Grid.ToolTip>
</Grid>
</UserControl>
If you don't use view models and host the data directly in the control, you may like to set the DataContext to the control itself. This way you simplify all bindings and of course can now bind to the UserControl from within the ToolTip:
// Constructor
public MyUserControl()
{
InitializeComponent();
// Set the UserControl's DataContext to the control itself
this.DataContext = this;
}
<UserControl>
<Grid>
<Grid.ToolTip>
<ToolTip>
<TextBlock Text="{Binding InfoTT}" />
</ToolTip>
</Grid.ToolTip>
</Grid>
</UserControl>
Alternatively override the DataContext. Of course you'll lose access to the current context:
<UserControl>
<Grid DataContext="{Binding RelativeSource={RelativeSource AncestoType=UserControl}>
<Grid.ToolTip>
<ToolTip>
<TextBlock Text="{Binding InfoTT}" />
</ToolTip>
</Grid.ToolTip>
</Grid>
</UserControl>
I have an Xceed DataGrid with an EditTemplate defined for the grid.
The grid shows a listing of items bound to a collection with about 6 columns and the EditTemplate is a TextBox control for entering a quantity. I want the IsReadOnly property to be bound to a different property so that the item has a serial number, IsReadOnly will be set to true so the user cannot enter a value. I want to bind to the SerialNum property within the same collection and pass it to a converter to return the true/false value. I've got the converter written; however, I'm having issues binding to the property to pass to the converter.
My DataGridCollectionViewSource is simple enough:
<xcdg:DataGridCollectionViewSource x:Key="transferItems" Source="{Binding TransferItems}" />
TransferItems is set in my ViewModel and all of the columns get properly bound.
For all of my generic display columns, they are being properly displayed via:
<xcdg:Column Title="Serial No." AllowSort="False" FieldName="SerialNum" />
My issue is in defining the xcgd:CellEditor template and I'm pretty sure my issue is around the RelativeSource. I've tried many different combinations trying to get the TransferItems.SerialNum property from my ViewModel, but no combination is working.
This is what I currently have:
<xcdg:Column Title="Xfer Qty Good" TextWrapping="Wrap" ReadOnly="False" Width="50" AllowGroup="False" AllowSort="False" FieldName="TransferQtyGood">
<xcdg:Column.CellEditor>
<xcdg:CellEditor>
<xcdg:CellEditor.EditTemplate>
<DataTemplate>
<TextBox x:Name="QtyGood" Margin="2,2,2,2" Width="50" HorizontalAlignment="Center" VerticalAlignment="Center"
Text="{xcdg:CellEditorBinding}" IsReadOnly="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type xcdg:DataGridCollectionViewSource}}, Path=DataContext.TransferItems.SerialNum, Converter={StaticResource serialToEnabledConverter}}"
/>
</DataTemplate>
</xcdg:CellEditor.EditTemplate>
</xcdg:CellEditor>
</xcdg:Column.CellEditor>
</xcdg:Column>
Which gives the runtime error:
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='Xceed.Wpf.DataGrid.DataGridCollectionViewSource', AncestorLevel='1''. BindingExpression:Path=DataContext.TransferItems.SerialNum; DataItem=null; target element is 'TextBox' (Name='QtyGood'); target property is 'IsReadOnly' (type 'Boolean')
I understand what the error is telling me, but I'm just getting the proper RelativeSource path. I've read some of the helpful posts here on the enumerations for RelativeSource and still am missing something.
Just in case someone is having this issue, I was able to finally get the binding working in this manner. The key is defining the correct RelativeSource path:
<TextBox x:Name="QtyGood" Margin="2,2,2,2" Width="50" HorizontalAlignment="Center" VerticalAlignment="Center"
Text="{xcdg:CellEditorBinding}" GotFocus="Qty_GotFocus" LostFocus="Qty_LostFocus"
IsReadOnly="{Binding RelativeSource={RelativeSource AncestorType={x:Type xcdg:DataRow}}, Path=DataContext.SerialNum, Converter={StaticResource serialToEnabledConverter}}"
/>
I have a TreeView with ContextMenu, and inside that menu I want to bind to a command on VIewModel
<TreeView x:Name="treeView"
ItemTemplate="{StaticResource ItemTemplate}"
ItemsSource="{Binding View}">
<TreeView.ContextMenu>
<ContextMenu>
<telerik:RadMenuItem Header="Remove" Command="{Binding RemoveCommand}" CommandParameter="{Binding ElementName=treeView, Path=SelectedItem, Mode=OneWay}" />
</ContextMenu>
</TreeView.ContextMenu>
</TreeView>
I receive an exception in Output window, like
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'ElementName=treeView'. BindingExpression:Path=SelectedItem; DataItem=null; target element is 'RadMenuItem' (Name=''); target property is 'CommandParameter' (type 'Object')
I am actually using RadTreeView, but the same applies for TreeView. Why I cannot bind to TreeView's SelectedItem property? I have tried with RelativeSource AncestorType, the same problem.
The problem is that, like the Popup control, it's a different visual tree. The error is telling you that it is trying to find a property called 'CommandParameter' on a 'RadMenuItem', because this is the DataContext it has within the ContextMenu's visual tree.
This will help you: Placement Target
I ended up setting the CommandTarget property of the MenuItem to the ContextMenu's PlacementTarget property, but it doesn't look like that's the approach you're taking. Even still, the PlacementTarget is what you're looking for.
I've got a TreeView to which I associate a ContextMenu. That contextmenu has an item whose IsChecked property I want to bind to my ViewModel. Since I am using a tree each treeitem is bound to a subproperty of my ViewModel.
In the VS2010 output window I am seeing this databinding error:
BindingExpression path error: 'IsAutoStart' property not found on 'object' ''HostMgmtViewModel' (HashCode=12565727)'. BindingExpression:Path=IsAutoStart; DataItem='HostMgmtViewModel'
This clearly shows it is trying to bind to my ViewModel and not to the treeitem's associated data. How do I bind to the correct object? Remember my contextmenu is associated with the whole TreeView not to the specific treeitem.
---------- Edit
As xandy pointed out below the resolution to my problem was to bind the IsChecked like this:
{Binding Path=PlacementTarget.SelectedItem.IsDisabledStart, Mode=OneWay, RelativeSource={RelativeSource AncestorType={x:Type ContextMenu}}}
<TreeView Name="tview" Grid.Row="0" Tag="{Binding RelativeSource={RelativeSource Self}, Path=SelectedItem}">
<TreeView.ContextMenu>
<ContextMenu>
<MenuItem Name="miC" Header="{Binding Path=Tag.Key}" DataContext="{Binding Path=PlacementTarget, RelativeSource={RelativeSource AncestorType={x:Type ContextMenu}}}"></MenuItem>
</ContextMenu>
</TreeView.ContextMenu>
</TreeView>
This is the working code snippet I have. Courtesy of [this].1 All you need is to change the binding path in the tag. I am currently binding the Treeview to a dictionary, so it is the Key property of it. It should not have any problem in binding to any object collections. One interesting finding is context menu is not in part of element tree and this cause the problem. I could bind the text box with no problem:
<TextBlock Grid.Row="1" DataContext="{Binding ElementName=tview, Path=SelectedItem}">
<TextBlock.Text>
<Binding Path="Key" />
</TextBlock.Text>
</TextBlock>
But it is not functioning if for menuitem if I put the same thing.