MVVM Light: Adding EventToCommand in XAML without Blend, easier way or snippet?

Question

Can anyone tell me what the actual syntax is for EventToCommand class. From what I believe is that EventToCommand class works with Silverlight / WPF and WP7, hence I think its a better choice to go down.

From what I believe, I can add any click event and get it forced into my ViewModel, but I am having an issue in finding the best way to do this.

I know you can add it without Blend, but are there snippets available?

Or is there an easier way to add it via VS 2010? Any help or if anyone knows of a good tutorial on this would be great.

I've created [a behavior](http://stackoverflow.com/a/16317999/385995) that does not require MVVMLight. It does require System.Windows.Interactivity, but so does the accepted answer. — Mike Fuchs, Sep 25 '14 at 17:28
Here's a post that talks about [all you need to know about EventToCommand](http://geekswithblogs.net/lbugnion/archive/2009/11/05/mvvm-light-toolkit-v3-alpha-2-eventtocommand-behavior.aspx) from the creator of MVVMLight ;) — AbdouMoumen, May 03 '11 at 14:56

Derek Beattie · Accepted Answer · 2016-03-21T16:34:51.977

84

Suppose you use .NetFramework4:

First add namespace:

xmlns:cmd="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Platform"

Syntax for the Loaded event.

<i:Interaction.Triggers>
    <i:EventTrigger EventName="Loaded">
        <cmd:EventToCommand Command="{Binding Mode=OneWay, Path=LoadedCommand}"
                            PassEventArgsToCommand="True" />
    </i:EventTrigger>
</i:Interaction.Triggers>

edited Mar 21 '16 at 16:34

answered May 03 '11 at 13:05

Derek Beattie

9,429
4
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1

How can this event be used by the view model then? – Ciaran Gallagher Nov 19 '12 at 19:41
3

It converts the event to a command, in the example, a Command on the view model called, LoadedCommand will be invoked. – Derek Beattie Nov 19 '12 at 21:38
Perfect, thanks. I matched up the command name with that of the command in my view model and it worked as expected. – Ciaran Gallagher Nov 19 '12 at 22:13
Is the `Mode=OneWay` bit necessary? It seems to work fine without it. – Dai Mar 01 '17 at 03:07
@Dai `OneWay` will update the target if the source changes, `TwoWay` will update the target if the source changes and also update the source if the target changes. – Derek Beattie May 02 '17 at 21:51
@DerekBeattie But when would the target ever change? – Dai May 03 '17 at 01:00
@Dai good point, I was thinking of a controls value being bound to a model property. – Derek Beattie May 03 '17 at 14:17
I 'm trying to use this EventToCommand into a listview to control ItemTapped,.... but where should I put this ???? – KillemAll Jan 24 '19 at 14:08

score 5 · Answer 2 · answered Nov 18 '15 at 20:10

5

I updated my project and it looks like they moved the command to:

xmlns:cmd="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Platform"

answered Nov 18 '15 at 20:10

Michael Shaffer

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2
16

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How does this differ from http://stackoverflow.com/a/5869889/11635 - ah I see, it was a late edit. This should really have been a comment on the other answer in that instance – Ruben Bartelink Jun 14 '16 at 10:24

Stepagrus · Answer 3 · 2017-11-17T08:29:41.740

0) if you dont't know WPF and MVVM, then read Josh Smith article about WPF and MVVM pattern https://msdn.microsoft.com/en-us/magazine/dd419663.aspx

1) In your project add package (through NuGet) MvvmLightLibs

2) add reference to System.Windows.Interactivity

3) In "View" XAML add:

a)

xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
xmlns:command="http://www.galasoft.ch/mvvmlight"

b)

<i:Interaction.Triggers>
    <i:EventTrigger EventName="Closing">
      <command:EventToCommand Command="{Binding OnClosingCommand}"/>
    </i:EventTrigger>
  </i:Interaction.Triggers>
</Window>

4) In ViewModel add necessary property

public ICommand OnClosingCommand
{
  get
  {
    return new RelayCommand(() => SomeMethod());
  }
}

P.S. In your View should be specified DataContext (XAML)

  <Window.DataContext>
    <vm:MainWindowViewModel/>
  </Window.DataContext>

It is work. I myself just learned.

I am traying to implement ItemTapped in a listview…… but I dont know where to put yoour code, can you helpme? — KillemAll, Jan 24 '19 at 14:26

MVVM Light: Adding EventToCommand in XAML without Blend, easier way or snippet?

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