Binding with multiple view models - wpf

Question

I have a viewmodel for a usercontrol that is defined in a data template for the viewmodel. I would like to bind the 'GridViewData' property of the usercontrol to the 'Data' property of the viewmodel.
I am still new to WPF and terrible at bindings, so please be kind :p
XAML:
<Window x:Class="ReportUtility.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:lite="clr-namespace:ReportUtility.Controls.LiteGrid"
xmlns:vm="clr-namespace:ReportUtility.ViewModels"
xmlns:wf="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
Title="MainWindow" Height="350" Width="525">
<!--This is the view model I want to bind to variable name is Grid: hosted in the content control below-->
<Window.Resources>
<DataTemplate DataType="{x:Type vm:LiteGridViewModel}">
<lite:LiteGrid GridViewData="{Binding ??}"/>
</DataTemplate>
</Window.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="auto"/>
<RowDefinition Height="50"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition Width="150"/>
</Grid.ColumnDefinitions>
<Button Grid.Row="0" Content="TestButton" HorizontalAlignment="Stretch" Command="{Binding ExecuteQueryCommand}"/>
<TextBox Grid.Row="1" Text="{Binding Path=SqlCommandText, UpdateSourceTrigger=PropertyChanged}"/>
<ContentControl Content="{Binding Grid}" Grid.Row="2" Background="Red"/>
<Border Background="Aqua" Grid.Column="1" Grid.RowSpan="3"/>
<GridSplitter Grid.Column="0" Width="3" Grid.RowSpan="3"/>
</Grid>

Answer 1

You would bind to Data
<DataTemplate DataType="{x:Type vm:LiteGridViewModel}">
<lite:LiteGrid GridViewData="{Binding Data}"/>
</DataTemplate>
It would even be better to do this binding in the LiteGrid UserControl instead of relying on the XAML that uses the control to set the value.
<UserControl GridViewData="{Binding Data}">
...
</UserControl>
Your bindings always reference the current object's DataContext. Since your DataTemplate is for type LiteGridViewModel, the DataContext within that DataTemplate is always going to be of type LiteGridViewModel.
For example, if you have a class like
public class MyClassA
{
MyClassB ClassB {get; set;}
}
public class MyClassB
{
MyClassC ClassC {get; set;}
}
And a ViewModel property of MyClassA ClassA (meaning you can reference ClassA.ClassB.ClassC), you could do something like
<ContentControl Content="{Binding ClassA}">
<ContentControl Content="{Binding ClassB}"> <!-- DataContext is MyClassA -->
<ContentControl Content="{Binding ClassC}"> <!-- DataContext is MyClassB -->
<!-- DataContext is MyClassC -->
</ContentControl>
</ContentControl>
</ContentControl>