WPF Binding Button to Command

Question

I have a screen that looks like this:

Screen Snapshot

Each colored area is a different UserControl put into the MainView.xaml as follows:

<UserControl Name="TopDockPanel" DockPanel.Dock="Top" Content="{Binding QuickInfoVM, Source={StaticResource Locator}}" />
<UserControl Name="LeftDockPanel" DockPanel.Dock="Left" Content="{Binding NavigationVM, Source={StaticResource Locator}}" />
<UserControl Name="RightDockPanel" DockPanel.Dock="Right" Content="{Binding MainContentVM, Source={StaticResource Locator}}" />

(I am using MVVMLight so Locator is the ViewModelLocator)

The green area is an ItemsControl area displaying buttons for each of the items (Company & Employee):

<UserControl x:Class="MvvmLightDemo.View.NavigationView"
             Name="Navigation"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:MvvmLightDemo.View"
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="120"
             DataContext="{Binding MainContentVM, Source={StaticResource Locator}}" >

    <StackPanel Background="CadetBlue">
        <ItemsControl ItemsSource="{Binding PageViewModels}">
            <ItemsControl.ItemTemplate>

                <ItemContainerTemplate>
                    <Button Content="{Binding Name}" 
                            Style="{StaticResource NavigationTextStyle}" 
                            Command="{Binding ChangePageCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:NavigationView}}}" />


                </ItemContainerTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>
    </StackPanel>
</UserControl>

The MainContentVM contains the ChangePageCommand as follows:

        public RelayCommand<IPageViewModel> ChangePageCommand
        {
            get
            {
                return _changePageCommand = new RelayCommand<IPageViewModel>(
                        p => ChangeViewModel((IPageViewModel)p),
                        p => p is IPageViewModel);

            }
        }

My question is, how do I bind the Buttons in the ItemContainerTemplate to the ChangePageCommand in MainContentVM? What I have doesn't work, when debugging the ChangePageCommand is never called when clicking either button.

When I use Command="{Binding ChangePageCommand, RelativeSource={RelativeSource AncestorType={x:Type local:NavigationView}}}" shouldn't that set the binding of the Command to that of the NavigationView (DataContext = MainContentVM)?

Bolu · Accepted Answer · 2013-09-12 14:31:56Z

3

try this:

 <Button Content="{Binding Name}" 
                            Style="{StaticResource NavigationTextStyle}" 
                            Command="{Binding DataContext.ChangePageCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:NavigationView}}}" />

Update:

 <Button Content="{Binding Name}" 
                                Style="{StaticResource NavigationTextStyle}" 
                                CommandParameter="{Binding}"
                                Command="{Binding DataContext.ChangePageCommand, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type local:NavigationView}}}" />

edited Sep 12, 2013 at 14:31

answered Sep 12, 2013 at 14:15

Bolu

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3 Comments

BrianKE Over a year ago

After changing to what you suggested my buttons are now light gray and the text is a medium gray and clicking on a button still does not call ChangePageCommand.

Bolu Over a year ago

@BrianKE, Further read your ChangePageCommand, shouldn't you provide a parameter (a IPageViewModel) with your Command binding? the button grayed out because p => p is IPageViewModel returns False, so the button is disabled.

BrianKE Over a year ago

That fixed it. Must have accidentally deleted it when trying various solutions to the binding.

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