Access ViewModel of sibling control

Question

I am aware there are some similar threads but I am still not sure of the best implementation.

The code should be self explanatory - check the comment there. How best to access that VIewModel.

part:FontSearchBox is a UserControl without a ViewModel - It just holds a TextBox for searching which needs to execute the command.

Thanks and appreciated.

<Grid>
    <Grid.RowDefinitions>
        <RowDefinition Height="35" />
        <RowDefinition Height="90" />
        <RowDefinition Height="*" />
    </Grid.RowDefinitions>

    <part:MainWindowControls Grid.Row="0" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" />

    <Grid Grid.Row="1">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="200" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <Image Source="/Typesee;component/Resources/window_logo.png" Width="156" Height="45" Grid.Column="0" VerticalAlignment="Top" RenderOptions.BitmapScalingMode="NearestNeighbor" />

        <!-- THIS TEXTBOX NEEDS TO CALL A COMMAND (SearchCommand.Execute(string)) Which resides in the fontTreeViewControl's ViewModel (FontTreeViewModel) -->
        <part:FontSearchBox Grid.Column="1" HorizontalAlignment="Right" VerticalAlignment="Bottom" Margin="0,0,12,10" Width="250" DataContext="{Binding ElementName=fontTreeViewControl, Path=DataContext}" />
    </Grid>

    <vw:FontTreeView x:Name="fontTreeViewControl" Grid.Row="2" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" />

</Grid>

What you mean by `THIS TEXTBOX NEEDS TO CALL A COMMAND`? How textbox would be able to call a command? You want to bind some property of `part:FontSearchBox` to `fontTreeViewControl's ViewModel`? — sll, Nov 24 '11 at 23:04
In the code I want to call the command on an event like textchanged. Should I create an AttachedProperty and bind to that from the xaml? — Dominic, Nov 25 '11 at 00:15

score 1 · Accepted Answer · edited Jun 20 '20 at 09:12

if you sre using MVVMLight the You can use Event to Command for the ....

in your UserControl <vw:FontTreeView /> you must be having a TextBox so in TextBox Xaml you have to Write

Xaml

<i:Interaction.Triggers>
    <i:EventTrigger EventName="TextChanged">
        <Commands:EventToCommand Command="{Binding Path=TextChangedCommand}"/>
    </i:EventTrigger>
</i:Interaction.Triggers>

To know more about the the Aliases see this link. it also demonstrates how to pass the event argument to your ViewModel.... but you might not meed that so you can skip it...

If TextBox is outsite fontTreeViewControl.... then,

<StackPanel DataContext={Binding Path=DataContext,ElementName=fontTreeViewControl}>
    <TextBox >
    <i:Interaction.Triggers>
    <i:EventTrigger EventName="TextChanged">
        <Commands:EventToCommand Command="{Binding Path=TextChangedCommand}"/>
    </i:EventTrigger>
</i:Interaction.Triggers>
    </TextBox>
</StackPanel>

This might help you.... :)

Thanks, unfortunately the textbox is outside of the fontreeview control, but the command and functionality is inside it. Do you recommend MVVMLight? Been planning to use it for my next project. — Dominic, Nov 30 '11 at 13:44
@infensus yes... its really nice and easy to use... as far as your problem is concerned....see edited answer — Ankesh, Dec 01 '11 at 04:05

Access ViewModel of sibling control

1 Answers1

Xaml