Binding to viewmodel from inside a datatemplate

Question

I have multiple videos displayed they are bound with a videocollection in Mainviewmodel. Everything works fine untill I try to bind the enter command to Mainviewmodel. I Don't know the syntax for this. As it stands the binding is set to Video and not Mainviewmodel.

Errormessage:

'StartVideoCommand' property not found on 'object' ''Video'

Xaml:

<Window.Resources>
  <local:MainViewModel x:Key="MainViewModel"/>
</Window.Resources>
  <Grid DataContext="{StaticResource MainViewModel}">
    <ListBox ItemsSource="{Binding Videos}">
      <ListBox.ItemTemplate>
        <DataTemplate>
          <Grid>
            <Grid.InputBindings>

!!!           <KeyBinding Key="Enter" Command="{Binding StartVideo}" /> !Bound to Video not to Mainviewmodel grrr  

            </Grid.InputBindings>
             ... layout stuff
              <TextBlock Text="{Binding Title}" Grid.Column="0" Grid.Row="0" Foreground="White"/>
              <TextBlock Text="{Binding Date}" Grid.Column="0" Grid.Row="1" Foreground="White" HorizontalAlignment="Left"/>
              <TextBlock Text="{Binding Length}" Grid.Column="1" Grid.Row="1" Foreground="White" HorizontalAlignment="Right"/>
             ... closing tags

Does this answer your question? [WPF Databinding: How do I access the "parent" data context?](https://stackoverflow.com/questions/1127933/wpf-databinding-how-do-i-access-the-parent-data-context) — StayOnTarget, Mar 03 '21 at 14:04

score 47 · Accepted Answer · answered Aug 23 '13 at 00:02

47

Command="{Binding RelativeSource={RelativeSource AncestorType={x:Type Window}}, Path=DataContext.StartVideo}"

answered Aug 23 '13 at 00:02

Jeroen

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I had to bind to a command therefore I did: `Command="{Binding RelativeSource={RelativeSource AncestorType={x:Type UserControl}}, Path=DataContext.COMMAND_I_WANT_TO_BIND_TO}"` – Tono Nam Nov 19 '14 at 19:52

StayOnTarget · Answer 2 · 2020-06-02T11:29:35.070

Another approach would be to use ElementName binding instead of RelativeSource.

Example:

<Window x:Name="root" ... >

  ...

  Command="{Binding ElementName=root, Path=DataContext.StartVideo}"

  ...

A possible advantage over RelativeSource is that this is explicit; if someone changes the XAML hierarchy then relative references could break unintentionally. (Not likely in this specific example of binding to a Window however).

Also if your "root" element already is named then so much the better it is easy to take advantage of.

It is also somewhat more readable.

Binding to viewmodel from inside a datatemplate

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