I have TreeView with HierarchicalDataTemplate. On TreeView I have ContextMenu
<TreeView Name="_packageTreeView" ItemsSource="{Binding PackageExtendedList}" Behaviors:TreeViewInPlaceEditBehavior.IsEditable="True">
<TreeView.ContextMenu>
<ContextMenu StaysOpen="true">
<MenuItem Header="Добавить пакет" Height="20" Command="{Binding AddPackageCommand}"
CommandParameter="{Binding ElementName=_packageTreeView, Path=SelectedItem}">
<MenuItem.Icon>
<Image Source="/Resources/ManualAdd.png" Width="15" Height="15"></Image>
</MenuItem.Icon>
</MenuItem>
</ContextMenu>
</TreeView.ContextMenu>
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Childs}">bla bla bla</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
As you can see, I bind Command to menu item. AddPackageCommand defined in ViewModell class as usually. Invoke command works fine, but I always have null in CommandParameter. I found some questions similar to my, but I don't understand solutions. For example:
CommandParameters in ContextMenu in WPF
Anyway it doesn't work for me :( What am I doing wrong?
Updated
That seems to be working, but it's all the same, I don't understand why CommandParameter doesn't work with TreeView.Name.
CommandParameter="{Binding PlacementTarget, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}}"
for examplle, such a sample works fine
<i:EventTrigger EventName="SelectedItemChanged">
<i:InvokeCommandAction Command="{Binding PackageTreeItemChangeCommand}" CommandParameter="{Binding ElementName=_packageTreeView, Path=SelectedItem}"/>
</i:EventTrigger>
What's the hell...
And anyway, I have TreeView object in CommandParameter, not TreeViewItem. I can get SelectedItem from TreeView, but how can I send exactly TreeViewItem as CommandParameter?
to Sheridan
Question was WHY this doesn't work.
CommandParameter="{Binding ElementName=_packageTreeView, Path=SelectedItem}"
And this works
CommandParameter="{Binding PlacementTarget, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}}"
WHY sometimes I can use direct TreeView control name and sometimes I cannot.
As I understand, matter is different DataContext of TreeView control and ContextMenu because ContextMenu has its own VisualTree and it is not the part of TreeView ViaualTree.
Unfortunately, that approach doesn't work too, I have null again. I set TreeView.Tag, sure.
<ContextMenu DataContext="{Binding PlacementTarget.Tag, RelativeSource={
RelativeSource Self}}" StaysOpen="true">
<MenuItem Header="Добавить пакет" Height="20" Command="{Binding AddPackageCommand}"
CommandParameter="{Binding ElementName=_packageTreeView, Path=SelectedItem}">
<MenuItem.Icon>
<Image Source="/Resources/ManualAdd.png" Width="15" Height="15"></Image>
</MenuItem.Icon>
</MenuItem>
</ContextMenu>
This is the easiest way, but if I have SelectedItem property in ViewModel it has no sense bind it to CommandParameter, because I already have it in ViewModel.
<MenuItem Header="Добавить пакет" Height="20" Command="{Binding AddPackageCommand}"
CommandParameter="{Binding SelectedItem}">
<MenuItem.Icon>
<Image Source="/Resources/ManualAdd.png" Width="15" Height="15"></Image>
</MenuItem.Icon>
</MenuItem>
You showed us that you already have an answer... why on earth did you post yet another question on this same subject instead of simply following the example in the answer? It doesn't work for you, because you didn't copy the answer properly.
In your example post answer, the Tag property is set to the TreeView control that the menu is applied on, but you haven't done this.
Your next problem is that you have ignored this Tag property again in the CommandParameter... somehow, you have changed this from the correct answer:
CommandParameter="{Binding PlacementTarget.Tag, RelativeSource={RelativeSource
FindAncestor, AncestorType={x:Type ContextMenu}}}
to this in your question:
CommandParameter="{Binding PlacementTarget, RelativeSource={RelativeSource
FindAncestor, AncestorType={x:Type ContextMenu}}}"
All you needed to do was copy and paste it. All the same, you might have even more luck doing this:
<TreeView Tag="{Binding DataContext, RelativeSource={RelativeSource Self}}"
Name="_packageTreeView" ItemsSource="{Binding PackageExtendedList}"
Behaviors:TreeViewInPlaceEditBehavior.IsEditable="True">
<TreeView.ContextMenu>
<ContextMenu DataContext="{Binding PlacementTarget.Tag, RelativeSource={
RelativeSource Self}}" StaysOpen="true">
<MenuItem Header="Добавить пакет" Height="20" Command="{Binding AddPackageCommand}"
CommandParameter="{Binding ElementName=_packageTreeView, Path=SelectedItem}">
<MenuItem.Icon>
<Image Source="/Resources/ManualAdd.png" Width="15" Height="15"></Image>
</MenuItem.Icon>
</MenuItem>
</ContextMenu>
</TreeView.ContextMenu>
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Childs}">bla bla bla</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
Look at the TreeView.Tag property... this is set to its own DataContext, which means that whatever is set as the DataContext of the TreeView is now available in the Tag property object.
Next, look at the ContextMenu.DataContext property... this is set to the Tag property of the PlacementTarget, which is the control that the ContextMenu is applied to, or in this case, the Treeview.
If you haven't worked it out yet, this means that the DataContext of the ContextMenu is now set to the same object as the DataContext of the TreeView. If this is not what you want because your Command is on a different object, then just change the Binding path in the Tag property to point to wherever the object that had the Command is.
The last thing that you can do to make this simpler is to add a property to your view model/code behind that binds to the TreeView.SelectedItem property:
<TreeView SelectedItem="{Binding SelectedItem}"... />
Then you can simply refer to this property for your CommandParameter:
<MenuItem Header="Добавить пакет" Height="20" Command="{Binding AddPackageCommand}"
CommandParameter="{Binding SelectedItem}">
<MenuItem.Icon>
<Image Source="/Resources/ManualAdd.png" Width="15" Height="15"></Image>
</MenuItem.Icon>
</MenuItem>
This last part of course assumes that you have set your view model/code behind as the Tag property of the TreeView. If you still don't understand this, take a look at the Context Menus in WPF page on WPF Tutorial.NET.
UPDATE >>>
I simply don't understand why you posted this question. First you said you couldn't do something, but then provided us with a link to a valid solution in another post. After trying to help you, you then say that it did work, but you don't know why... but then you correctly answered your own question again:
As I understand, matter is different DataContext of TreeView control and ContextMenu because ContextMenu has its own VisualTree and it is not the part of TreeView ViaualTree.
As you said, the ContextMenu has its own visual tree. This means that it is not aware of controls, named or otherwise, in another visual tree. However, if the ContextMenu.DataContext is provided with an object such as the containing view, then it can be aware of controls in another visual tree (more specifically, the visual tree of the controls in the view).
This whole issue seems to be down to a lack of knowledge on your part about Binding in general and Binding.Path syntax more specifically. Please take a look at the following articles on MSDN for more help on this topic:
Binding.Path Property
Property Path Syntax
RelativeSource MarkupExtension
So many people try to run with WPF before they can walk.
Related
I have a static resource defined as follows:
<ContextMenu x:Key="TestContextMenu" DataContext="{Binding Path=PlacementTarget, RelativeSource={x:Static RelativeSource.Self}}">
<MenuItem Command="ApplicationCommands.Cut"/>
<!--<ContextMenu.ItemsSource>
<CompositeCollection>
<MenuItem Command="ApplicationCommands.Cut"/>
</CompositeCollection>
</ContextMenu.ItemsSource>-->
</ContextMenu>
My application works fine like this. However, I want to be able to add extra items to the context menu. So instead of adding menu items I want to use a CompositeCollection and then I run into binding issues. I minimized the problem and ended up with this. When I comment the MenuItem and uncomment the ContextMenu.ItemSource I get this error:
System.Windows.Data Error: 4 : Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.ItemsControl', AncestorLevel='1''. BindingExpression:Path=HorizontalContentAlignment; DataItem=null; target element is 'MenuItem' (Name=''); target property is 'HorizontalContentAlignment' (type 'HorizontalAlignment')
If the datacontext is correct in the first situation why is it not correct anymore in the second situation?
Edit: I don't want to add items to the contextmenu dynamically. I want to use this contextmenu as kind of a 'base context menu' providing cut/copy and paste from a composite collection resource. In some places I want more than just these three and there I could use a custom context menu that use that same collection combined with those extra items. Just to clarify this is the xaml I have in mind, but I cut the problem down to the simpler piece above.
<CompositeCollection x:Key="TreeViewItemContextMenuItems">
<MenuItem Command="ApplicationCommands.Cut" CommandTarget="{Binding}"/>
<MenuItem Command="ApplicationCommands.Copy" CommandParameter="{Binding}"/>
<MenuItem Command="ApplicationCommands.Paste" CommandParameter="{Binding}"/>
<Separator/>
<MenuItem Command="ApplicationCommands.Delete" CommandParameter="{Binding}"/>
</CompositeCollection>
<ContextMenu x:Key="TreeViewItemContextMenu" DataContext="{Binding Path=PlacementTarget, RelativeSource={x:Static RelativeSource.Self}}">
<ContextMenu.ItemsSource>
<CompositeCollection>
<CollectionContainer Collection="{StaticResource TreeViewItemContextMenuItems}" />
</CompositeCollection>
</ContextMenu.ItemsSource>
</ContextMenu>
If you want to dynamically populate ContextMenu the better solution is do to as follows:
<ContextMenu
x:Key="TestContextMenu"
ItemsSource="{Binding MenuItems}">
</ContextMenu>
I removed DataContext="{Binding Path=PlacementTarget...}}" and added this ItemsSource="{Binding MenuItems}". MenuItems is a property of an object used as a data context. Here is an example of usage:
<Window>
...
<ItemsControl ContextMenu="{StaticResource ResourceKey=TestContextMenu}">
...
</ItemsControl>
</Window
In this case the context menu will inherit a data context from ItemsControl which in turn will inherit a data context from Window.
If you don't want to remove DataContext="{Binding Path=PlacementTarget...}}" then use the following code:
<ContextMenu
x:Key="TestContextMenu"
DataContext="{Binding Path=PlacementTarget, RelativeSource={x:Static RelativeSource.Self}}"
ItemsSource="{Binding DataContext.MenuItems}">
</ContextMenu>
EDIT:
You receive these errors because MenuItem controls by default try to bind some of their properties (HorizontalContentAlignment and VerticalContentAlignment) to ItemsControl using RelativeSource. The problem is that their are embeded inside CompositeCollection which doesn't support this kind of binding - see this article.
The problem will occure even if you override this binding in your XAML in this way:
<MenuItem Command="ApplicationCommands.Cut" CommandTarget="{Binding}"
HorizontalContentAlignment="Center" VerticalContentAlignment="Center"/>
Probably there is some workaround of this problem but personally I'll ignore these errors. They don't spoil anything in your application, don't they?
I'm trying to bind a command to a menuitem in WPF. I'm using the same method that's been working for all my other command bindings, but I can't figure out why it doesn't work here.
I'm currently binding my commands like this:
Command = "{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.MyCommand}"
This is where it goes wrong (this is inside a UserControl)
<Button Height="40" Margin="0,2,0,0" CommandParameter="{Binding Name}"
Command = "{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.ConnectCommand}">
<Button.ContextMenu>
<ContextMenu>
<MenuItem Header="Remove" CommandParameter="{Binding Name}"
Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.RemoveCommand}"/>
</ContextMenu>
</Button.ContextMenu>
...
The first command binding works like it should, but the second one refuses to do anything.
I've tried changing the ancestor level and naming my Control to access it through ElementName instead of RelativeSource, but still no change. It keeps saying "Cannot find source for binding with reference..."
What am I missing?
(Edit) Since you mentioned this is in an ItemsControl's template, things are different:
1) Get the BindingProxy class from this blog (and read the blog, as this is interesting information): How to bind to data when the DataContext is not inherited.
Basically the elements in the ItemsControl (or ContextMenu) are not part of the visual or logical tree, and therefore cannot find the DataContext of your UserControl. My apologies for not writing more on this here, but the author has done a good job explaining it step by step, so there's no way I could give a complete explanation in just a few lines.
2) Do something like this: (you may have to adapt it a bit to make it work in your control):
a. This will give you access to the UserControl DataContext using a StaticResource:
<UserControl.Resources>
<BindingProxy
x:Key="DataContextProxy"
Data="{Binding}" />
</UserControl.Resources>
b. This uses the DataContextProxy defined in (a):
<Button.ContextMenu>
<ContextMenu>
<MenuItem Header="Remove" CommandParameter="{Binding Name}"
Command="{Binding Path=Data.RemoveCommand, Source={StaticResource DataContextProxy}}"/>
</ContextMenu>
This has worked for us in things like trees and datagrids.
ContextMenu is in different logical tree, that's why RelativeSource doesnt work. But context menu inherit DataContext from its "container", in this case it is Button. It is enough in common case but in your case you need two "data contexts", of ItemsControl item and of ItemsControl itself.
I think you have no other choice but combine your view models into one, implement custom class to be used as ItemsControl item data context and contain both "Name" and "Remove command" or your item's view model can define RemoveCommand "proxy", that would call parent command internally
EDIT:
I slightly changed Baboon's code, it must work this way:
<Button Height="40" Margin="0,2,0,0" CommandParameter="{Binding Name}"
Tag="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}}"
Command = "{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.ConnectCommand}">
<Button.ContextMenu>
<ContextMenu>
<MenuItem Header="Remove"
CommandParameter="{Binding Name}"
Command="{Binding Path=PlacementTarget.Tag.DataContext.RemoveCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=ContextMenu}}"/>
</ContextMenu>
</Button.ContextMenu>
koshdim is spot on, it works like a charm!! Thanks Koshdim
I modified his code to fit in my context menu
<DataGrid
AutoGenerateColumns="False"
HeadersVisibility="Column"
Name="dgLosses"
SelectedItem="{Binding SelectedItem, Mode= TwoWay}"
AllowDrop="True"
ItemsSource="{Binding Losses}"
Tag="{Binding DataContext,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=Window}}">
<DataGrid.ContextMenu >
<ContextMenu >
<MenuItem Header="Move to Top " Command="{Binding PlacementTarget.Tag.MoveToTopCommand,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=ContextMenu}}" ></MenuItem>
<MenuItem Header="Move to Period 1" Command="{Binding PlacementTarget.Tag.MoveToPeriod1Command,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=ContextMenu}}" ></MenuItem>
<MenuItem Header="Move to Period 2" Command="{Binding PlacementTarget.Tag.MoveToPeriod2Command,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=ContextMenu}}" ></MenuItem>
<MenuItem Header="Move to Period 3" Command="{Binding PlacementTarget.Tag.MoveToPeriod3Command,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=ContextMenu}}" ></MenuItem>
</ContextMenu>
</DataGrid.ContextMenu>
That's a tricky issue, sure marginally you will find a quick workaround, but here is a no-magic-solution:
<Button Height="40" Margin="0,2,0,0" CommandParameter="{Binding Name}"
Tag={Binding}
Command = "{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.ConnectCommand}">
<Button.ContextMenu>
<ContextMenu>
<MenuItem Header="Remove"
CommandParameter="{Binding Path=PlacementTarget.Tag.Name, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=ContextMenu}}"
Command="{Binding Path=PlacementTarget.Tag.RemoveCommand, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=ContextMenu}}"/>
</ContextMenu>
</Button.ContextMenu>
...
It boils down to using the Tag of the PlacementTarget (the Button here).
I have a treeview bound to a Observable collection of some property type. There is a HierarchicalDataTemplate that shows the data in treeview. Now i need to show specific context menu for each HierarchicalDataTemplate item.
I am using the following XAML to show context menu:
<HierarchicalDataTemplate ItemsSource="{Binding Collections}">
<TextBlock Text="{Binding Path=Name}">
<TextBlock.ContextMenu>
<ContextMenu>
<MenuItem Header="Create" Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}}, Path=DataContext.AddCommand}" CommandParameter="{Binding}"/>
</ContextMenu>
</TextBlock.ContextMenu>
</TextBlock>
</HierarchicalDataTemplate>
Here the AddCommand is written in the view model that is bound to this under control..
I am able to see the context menu, but event is not firing on click on menu item.
Please help..
Your command binding will not work because the ContextMenu is not on the same logical tree as your UserControl is, therefore it will not find the UserControl ancestor. However your ContextMenu should inherit its container's datacontext automatically.
So this should work -
<ContextMenu>
<MenuItem Header="Create" Command="{Binding AddCommand}" CommandParameter="{Binding}"/>
</ContextMenu>
However the AddCommand property should exist on your HierarchicalDataTemplate bound item.
EDIT:
If your Command is not defined in your HierarchicalDataTemplate's bound item and instead in your UserControl. Then another think you may try is giving your UserControl a name, and then bind the command to it by ElementName. Like this
Updated again:
<ContextMenu>
<MenuItem Header="Create" Command="{Binding ElementName="MyUserControl" Path="DataContext.AddCommand"}" CommandParameter="{Binding}"/>
</ContextMenu>
I created a WPF application and am following MVVM Pattern. I have a context menu in my xaml and I need to bind the command and Header text. Using the following code I can bind the Header of the context menu with the "MenuItemName" which is a property in BOList which is an observable collection. My issue is that command is not getting fired? I changes the Item source of the Context Menu to datacontext
(DataContext="{Binding Path=PlacementTarget.Tag, RelativeSource={RelativeSource Self}}")
Command is working fine but my header is getting blank. Is there a way to bind my header and command of a menu item? Here the command MenuClick is a Icommand property in the VM and MenuItemName is a property inside BOList which is an observable collection binded to my ListBox.
<Grid>
<StackPanel Orientation="Vertical">
<Button x:Name="btnClickMe" Command="{Binding ButtonCommand}" Content="Click Me" />
<ListBox ItemsSource="{Binding BOList}" x:Name="lstDemo" SelectedItem="{Binding BussinessObj,Mode=OneWayToSource}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel x:Name="stkStyleRender" Orientation="Horizontal" Background="Cyan" Width="525" Tag="{Binding DataContext, RelativeSource={RelativeSource AncestorType={x:Type ListBox}}}" >
<TextBlock x:Name="txtId" Text="{Binding FirstName}"></TextBlock>
<TextBlock x:Name="txtName" Text="{Binding LastName}"></TextBlock>
<StackPanel.ContextMenu>
<ContextMenu x:Name="cntMnuTest" ItemsSource ="{Binding Path=PlacementTarget.Tag, RelativeSource={RelativeSource Self}}" >
<MenuItem Header="{Binding MenuItemName}" Command="{Binding MenuClick}" CommandParameter="Icon"></MenuItem>
</ContextMenu>
</StackPanel.ContextMenu>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</StackPanel>
Hi Identified the issue.
If we set Item Source of the context menu to BOList (observable collection ) command wont get fired because the ICommand definition is in Window data context (vm).
We need to handle the code like wise.
Since debugging is not possible for binding , I was beating around the bush :-)
This link helped me a lot WPF Tutorial - Debug Databinding Issues in WPF
In context menu use DataContext instead of using Items source
then bind your menu item
try this:
<MenuItem Header="{Binding Path=PlacementTarget.MenuItemName, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}" Command="{Binding Path=PlacementTarget.MenuClick, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}" />
I currently have a UserControl that uses the MVVM model.
In that control there is a TreeView, which displays some items. I have added a HierarchicalDataTemplate for this TreeView and in that template is a ContextMenu for the Items.
In the ViewModel, which is DataContext of the control (named RestoresTreeViewControl) is a command I want to bind one of the menu items to. However what I have done doesn't seem to be working. I am getting the usual can't find source for binding reference.
Here is the bit of code for the datatemplate that tried to bind the EditDatabaseCommand to one of the menu items.
<HierarchicalDataTemplate DataType="{x:Type model:Database}" >
<StackPanel>
<TextBlock Text="{Binding Name}" >
<TextBlock.ContextMenu>
<ContextMenu>
<MenuItem Header="Edit" Command="{Binding ElementName=RestoresTreeViewControl, Path=DataContext.EditDatabaseCommand}" />
<MenuItem Header="Delete"/>
<Separator/>
<MenuItem Header="Test Connection"/>
</ContextMenu>
</TextBlock.ContextMenu>
</TextBlock>
</StackPanel>
</HierarchicalDataTemplate>
Here is a section of the ViewModel where the command is.
public ICommand EditDatabaseCommand { get; private set; }
Unfortunately the ContextMenu is not in the VisualTree, so it's not going to see your DataContext. What you can do is something like this (copied from here: MVVM binding command to contextmenu item)
<Button Height="40" Margin="0,2,0,0" CommandParameter="{Binding Name}"
Tag="{Binding RelativeSource={RelativeSource Mode=FindAncestor,
AncestorType={x:Type UserControl}}}" Command = "{Binding
RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type UserControl}},
Path=DataContext.ConnectCommand}">
<Button.ContextMenu>
<ContextMenu>
<MenuItem Header="Remove"
CommandParameter="{Binding Name}"
Command="{Binding Path=PlacementTarget.Tag.DataContext.RemoveCommand,
RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=ContextMenu}}"/>
</ContextMenu>
</Button.ContextMenu>
So simply use PlacementTarget.Tag to find your ViewModel.
You can try tracing the binding:
xmlns:diag="clr-namespace:System.Diagnostics;assembly=WindowsBase"
...
{binding ... diag:PresentationTraceSources.TraceLevel="High"}
However requiring the users (even if it is just yourself) of your control to name each instance of "RestoresTreeViewControl" rather burdensome.
Try:
{Binding Path=... RelativeSource={ FindAncestor, AncestorType={x:TheRestoresTreeViewControlType}} }
That probably has to do with the inheritance context.
See: Binding WPF ContextMenu MenuItem to UserControl Property vs ViewModel Property