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}}" />
Related
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.
Is there a way to do a Mouse- or KeyBinding in a WPF treeview?
<TreeView ItemsSource="{Binding Main.TreeItems}">
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Path=Children}">
<TextBlock Text="{Binding Path=Header}">
<TextBlock.InputBindings>
<MouseBinding Command="{Binding TreeViewClickCommand}" MouseAction="LeftDoubleClick"/>
</TextBlock.InputBindings>
</TextBlock>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
This doesn't work. If i use my Command on a button not in the treeview then the command is fired. How can i solve this problem?
If this Command works outside the TreeView, I assume your TreeViewClickCommand is located in the DataContext of your Window/UserControl.
Use AncestorType to refer to the TreeViews DataContext (which is the same as the Windows DC, if you did not set it manuelly):
Command="{Binding RelativeSource={RelativeSource AncestorType={x:Type TreeView}}, Path=DataContext.TreeViewClickCommand}"
You can use AttachedCommandBehavior to do this.
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
<DataTemplate x:Key="_ItemTemplateA">
<Grid Tag="{Binding Path=DataContext.Command, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}}}">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<ContentControl Content="{Binding}" ContentTemplate="{StaticResource ContentTemplateB}" Grid.Row="0" />
<ContentControl Name="uiContentPresenter" Content="{Binding ContentView}" Grid.Row="1" Height="0" />
<ContentControl DataContext="{Binding IsContentDisplayed}" DataContextChanged="IsDisplayed_Changed" Visibility="Collapsed" />
<Grid.ContextMenu>
<ContextMenu>
<MenuItem Header="Text"
Command="{Binding Path=PlacementTarget.Tag, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}}"
CommandParameter="{Binding}" />
</ContextMenu>
</Grid.ContextMenu>
</Grid>
</DataTemplate>
The above data template is applied to an ItemsControl. The issue is that for the ContextMenu that is specified for the Grid, the PlacementTarget property is never actually getting set to anything so I cannot get to the Tag property of the Grid which is necessary for passing the Command that should execute on the parent UserControl down to the context menu. I've based this approach off of similar examples such as this: http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/0244fbb0-fd5f-4a03-bd7b-978d7cbe1be3/
I've not been able to identify any other good way to pass this command down. This is setup this way because we are using an MVVM approach so the command we have to execute lives in the View Model of the user control this template is applied in. I've tried explicitly setting the PlacementTarget in a few different ways but it still always shows up as not set.
I realise that this is old and answered, but it doesn't seem properly answered. I came across a similar post and left a full answer. You might like to take a look as you can get it working with just a few adjustments to your code.
First, name your view UserControl... I generally name all of mine This for simplicity. Then remembering that our view model is bound to the DataContext of the UserControl, we can bind to the view model using {Binding DataContext, ElementName=This}.
So now we can bind to the view model, we have to connect that with the ContextMenu.DataContext. I use the Tag property of the object with the ContextMenu (the PlacementTarget) as that connection, in this example, a Grid:
<DataTemplate x:Key="YourTemplate" DataType="{x:Type DataTypes:YourDataType}">
<Grid ContextMenu="{StaticResource Menu}" Tag="{Binding DataContext,
ElementName=This}">
...
</Grid>
</DataTemplate>
We can then access the view model properties and commands in the ContextMenu by binding the ContextMenu.DataContext property to the PlacementTarget.Tag property (of the Grid in our example):
<ContextMenu x:Key="Menu" DataContext="{Binding PlacementTarget.Tag, RelativeSource=
{RelativeSource Self}}">
<MenuItem Header="Delete" Command="{Binding DeleteFile}" CommandParameter=
"{Binding PlacementTarget.DataContext, RelativeSource={RelativeSource
AncestorType=ContextMenu}}" CommandTarget="{Binding PlacementTarget,
RelativeSource={RelativeSource Self}}" />
</ContextMenu>
Note the binding on the MenuItem.CommandTarget property. Setting this ensures that the target element on which the specified command is raised is the PlacementTarget, or the Grid in this case.
Also note the CommandParameter binding. This binds to the DataContext of the PlacementTarget, or the Grid in this case. The DataContext of the Grid will be inherited from the DataTemplate and so your data item is now bound to the object parameter in your Command if you're using some implementation of the ICommand interface:
public bool CanExecuteDeleteFileCommand(object parameter)
{
return ((YourDataType)parameter).IsInvalid;
}
public void ExecuteDeleteFileCommand(object parameter)
{
Delete((YourDataType)parameter);
}
Or if you are using some kind of RelayCommand delegates directly in your view model:
public ICommand Remove
{
get
{
return new ActionCommand(execute => Delete((YourDataType)execute),
canExecute => return ((YourDataType)canExecute).IsInvalid);
}
}
We have the same problem, but it works randomly. A contextmenu inside the controltemplate in a style for a listbox. We have tried to move the contextmenu to different levels inside the template but the same error occurs.
We think it might be connected to the refreshing of our ICollectionView that is the itemssource of the ListBox.
It seems that when the view refreshes the relative source binding inside the contextmenu is being evaluated before the PlacementTarget is being set.
It feels like a bug in either collectionviewsource or the ContextMenu of WPF...
Here is a working standalone XAML-only example based on your test case: a ContextMenu that retrieves a Command from the DataContext of its PlacementTarget using a Tag. You can reintroduce portions of your code until it stops working to try to find where the problem is:
<Grid>
<Grid.Resources>
<PointCollection x:Key="sampleData">
<Point X="10" Y="20"/>
<Point X="30" Y="40"/>
</PointCollection>
<DataTemplate x:Key="_ItemTemplateA">
<Grid Tag="{Binding Path=DataContext, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type DockPanel}}}">
<TextBlock Text="{Binding X}"/>
<Grid.ContextMenu>
<ContextMenu>
<MenuItem Header="{Binding Path=PlacementTarget.Tag, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ContextMenu}}}" CommandParameter="{Binding}"/>
</ContextMenu>
</Grid.ContextMenu>
</Grid>
</DataTemplate>
</Grid.Resources>
<DockPanel DataContext="{x:Static ApplicationCommands.Open}">
<ListBox ItemTemplate="{StaticResource _ItemTemplateA}" ItemsSource="{StaticResource sampleData}"/>
</DockPanel>
</Grid>
In this post,
ContextMenu.PlacementTarget is filled up from ContextMenuService.PlacementTarget when you do right click with mouse on button.
It means ContextMenu.PlacementTarget is filled up when the menu is shown up. You can check that by snoop.
EDIT 1
This code works fine.
<DataGrid.RowStyle>
<Style TargetType="DataGridRow" BasedOn="{StaticResource DataGridRowBaseStyle}">
<Setter Property="Tag" Value="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=DataGrid}, Path=DataContext}"/>
<Setter Property="ContextMenu">
<Setter.Value>
<ContextMenu Style="{StaticResource ContextMenuStyle}"
ItemContainerStyle="{StaticResource MenuItemStyle}">
<MenuItem Header="Enable" Command="{Binding Path=PlacementTarget.Tag.(viewModels:PrinterListPageViewModel.EnableCommand), RelativeSource={RelativeSource AncestorType=ContextMenu}}"/>
</ContextMenu>
</Setter.Value>
</Setter>
</Style>
</DataGrid.RowStyle>
I have an ItemsControl whose for the ItemTemplate DataTemplate contains a Button. I want the Command on the button to bind to a Command on the DataContext of the ItemsControl, not the ItemTemplate. I think the solution has to do with using RelativeSource, but my attempts so far have failed:
<ItemsControl ItemsSource="{Binding Games}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Button Command="{Binding Path=GameSelectedCommand, Source={RelativeSource FindAncestor, AncestorType={x:Type ItemsControl}}}"
CommandParameter="{Binding}"
Style="{StaticResource MenuButtonStyle}"
Content="{Binding Name}"/>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
How can I get the Button to bind to the GameSelectedCommand of the ItemsControl's DataContext object?
You're setting the source of the binding to the ItemsControl itself. Therefore, you'll need to dereference the DataContext of the ItemsControl:
Command="{Binding DataContext.GameSelectedCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ItemsControl}}}"
How would you have known this? Take a look at your debug output window when running the app. You'll see a message along the lines of "Cannot resolve property 'GameSelectedCommand' on type 'ItemsControl'".