MVVM: Binding a ViewModel which takes constructor args to a UserControl - wpf

Question

My WPF app has a MainWindow containing a usercontrol called TvshowGridView.
MainWindow:
<Window
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:NevermissClient"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
xmlns:views="clr-namespace:NevermissClient.Views"
x:Class="NevermissClient.MainWindow"
x:Name="Window">
<Grid x:Name="LayoutRoot">
<views:TvshowGridView x:Name="TheTvshowGridView" Margin="8,8,8,58.96" Grid.Row="1"/>
</Grid>
</Window>
TvshowGridView:
<UserControl
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:viewModels="clr-namespace:NevermissClient.ViewModels"
xmlns:telerik="http://schemas.telerik.com/2008/xaml/presentation"
mc:Ignorable="d"
x:Class="NevermissClient.Views.TvshowGridView"
d:DesignWidth="640" d:DesignHeight="480">
<Grid x:Name="LayoutRoot">
<telerik:RadGridView x:Name="TvshowGrid" d:LayoutOverrides="Width, Height" AutoGenerateColumns="False" ItemsSource="{Binding AllEpisodes}" IsReadOnly="False">
<telerik:RadGridView.Columns>
<telerik:GridViewDataColumn DataMemberBinding="{Binding TvshowName, Mode=TwoWay}" Header="Tvshow Name" IsReadOnly="False"/>
<telerik:GridViewDataColumn DataMemberBinding="{Binding Name, Mode=TwoWay}" Header="Episode Name"/>
<telerik:GridViewDataColumn DataMemberBinding="{Binding Airdate, Mode=TwoWay}" Header="Airdate"/>
</telerik:RadGridView.Columns>
</telerik:RadGridView>
</Grid>
</UserControl>
The view model, TvshowGridViewModel, that I wish to bind to the TvshowGridView has a constructor that takes arguments.
public class TvshowGridViewModel : BaseViewModel
{
private EpisodeRepository _episodeRepository;
private TvshowRepository _tvshowRepository;
public ObservableCollection<EpisodeViewModel> AllEpisodes { get; private set; }
public TvshowGridViewModel(EpisodeRepository episodeRepository, TvshowRepository tvshowRepository)
{
_episodeRepository = episodeRepository;
_tvshowRepository = tvshowRepository;
CreateAllEpisodes();
}
...
}
These arguments are defined in MainWindowViewModel, the view model connected to the MainWindow. - So this seems like the logical place to create the TvshowGridViewModel.
public class MainWindowViewModel : BaseViewModel
{
readonly TvshowGridViewModel _tvshowGridViewModel;
readonly EpisodeRepository _episodeRepository;
readonly TvshowRepository _tvshowRepository;
public MainWindowViewModel()
{
_episodeRepository = new EpisodeRepository("c:\data.xml");
_tvshowRepository = new TvshowRepository("c:\data.xml");
_tvshowGridViewModel = new TvshowGridViewModel(_episodeRepository, _tvshowRepository);
}
public TvshowGridViewModel TvshowGridViewModel { get; }
...
}
How can I bind the instantiated TvshowGridViewModel to the TvshowGridView? (Avoiding codebehind)
Thanks!

Answer 1

Assuming that your MainWindows Datacontext is an instance of MainWindowViewModel, you can bind the usercontrol to TvshowGridViewModel like this:
<Window>
...
<Grid x:Name="LayoutRoot">
<views:TvshowGridView DataContext={Binding TvshowGridViewModel} x:Name="TheTvshowGridView" Margin="8,8,8,58.96" Grid.Row="1"/>
</Grid>
You also should change the TvshowGridViewModel property code like shown:
public TvshowGridViewModel TvshowGridViewModel
{ get{return _tvshowGridViewModel;} }