Is it possible to set e.Handled = true in a RelayCommand?

Question

So I've got a hyperlink that I have hooked up to the code behind like so:

Xaml

<TextBlock x:Name="Hyperlink" HorizontalAlignment="Left" VerticalAlignment="Bottom" Margin="3" FontSize="14" Foreground="White">           
      <Hyperlink NavigateUri="{Binding StreetViewString}" RequestNavigate="Hyperlink_RequestNavigate" Foreground="White" StylusDown="Hyperlink_StylusDown" TouchDown="Hyperlink_TouchDown">
             Google
      </Hyperlink>
</TextBlock>

Code Behind

private void addToDiary_MouseDown(object sender, MouseButtonEventArgs e)
{
    ((sender as Button).DataContext as MyViewModel).MyCommand.Execute(null);
    e.Handled = true;
}

But I would like to hook this straight up to the command it is executing

    private ICommand _myCommand;
    public ICommand MyCommand
    {
        get
        {
            return _myCommand
                ?? (_myCommand= CommandFactory.CreateCommand(
                () =>
                {
                    DoSomething();
                }));
        }
    }

but the only thing that is stopping me is that I cannot set e.Handled = true from my command. Is it possible to do this without using the code behind?

If you had ICommand which if you don't use any framework like prism or mvvm light, does not come out of the box. Then you can pass your MouseButtonEventArgs as a parameter in Execute, and then you can do what you want with it. — adminSoftDK, May 06 '15 at 08:06
@adminSoftDK I could implement `ICommand` but my next question would be could I do this so that I dont need the code behind. I.e. send the `MouseButtomEventArgs` straight from the Xaml? — JKennedy, May 06 '15 at 08:10
I don't know anyway of doing it without the code behind. I am doing something similar on application close. Maybe somebody else will help with this question :) — adminSoftDK, May 06 '15 at 08:14
MVVM != no codebehind, and performing UI logic in the VM (killing event bubbling, for example) != MVVM. — , May 06 '15 at 14:07
MVVM can have 'code-behind' but only for View concerns, not for accessing the DataContext aka the ViewModel. One might say, 'if you're doing MVVM properly you don't have code-behind files, only attached behaviors, which are code-behind files :)' — AwkwardCoder, May 06 '15 at 14:34

score 0 · Accepted Answer · answered May 06 '15 at 08:48

0

I am going to presume you're using MVVM and ideally you want to be able to 'handle' the click of the hyperlink in the ViewModel and not in the View - which is the correct way to do this.

In which you are probably best using a normal WPF button which has been styled to look like a hyperlink and then bind in the Command property of the button to an instance of your ICommand implmentation.

The following should style the button:

<Style x:Key="HyperLinkButton"
       TargetType="Button">
    <Setter
        Property="Template">
        <Setter.Value>
            <ControlTemplate
                TargetType="Button">
                <TextBlock
                    TextDecorations="Underline">
                <ContentPresenter /></TextBlock>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
    <Setter
        Property="Foreground"
        Value="Blue" />
    <Style.Triggers>
        <Trigger
            Property="IsMouseOver"
            Value="true">
            <Setter
                Property="Foreground"
                Value="Red" />
        </Trigger>
    </Style.Triggers>
</Style>

Applying the Style and binding the Command property, this requires you have bound the DataContext of the containing control\view to the ViewModel. as I said if you are doing MVVM this should be obvious:

<Button Style="{StaticResource HyperLinkButton}"
        Content="Some Link"
        Command={Binding Path=MyCommand, Mode=OneWay/>

answered May 06 '15 at 08:48

AwkwardCoder

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Thanks for the answer, though it doesn't really answer my question. there is a `command` property I can use on the `Hyperlink` object. The only reason I currently haven't done this is because I cannot set the `EventArgs` to handled in the command and was wondering if there was a way to do this – JKennedy May 06 '15 at 08:54
yes I am. This is why I would like to remove the `e.Handled` from the code behind – JKennedy May 06 '15 at 10:09
so not the solution I provide, it completes keeps the UI concerns out of the ViewModel. – AwkwardCoder May 06 '15 at 10:13
Oh yes I see what you mean now because the button autoamtically sets e.handled so the event doesnt bubble up. Thanks – JKennedy May 06 '15 at 10:15
1

Exactly - the user thinks it's a hyperlink button, but in reality it is a normal WPF button and it has the standard button behavior you want - as in the event does not bubble up – AwkwardCoder May 06 '15 at 10:18
it may be worth adding that explanation to the answer to clarify that this answers the question – JKennedy May 06 '15 at 10:31

Is it possible to set e.Handled = true in a RelayCommand?

1 Answers1