mvvm - How to fire a Command when a window is loaded in wpf

Question

Is it possible to fire a command to notify the window is loaded. Also, I'm not using any MVVM frameworks (Frameworks in the sense, Caliburn, Onxy, MVVM Toolkit etc.,)

Answer 1

To avoid code behind on your View, use the Interactivity library (System.Windows.Interactivity dll which you can download for free from Microsoft - also comes with Expression Blend).

Then you can create a behavior that executes a command. This way the Trigger calls the Behavior which calls the Command.

<ia:Interaction.Triggers>
    <ia:EventTrigger EventName="Loaded">
        <custombehaviors:CommandAction Command="{Binding ShowMessage}" Parameter="I am loaded"/>
    </ia:EventTrigger>
</ia:Interaction.Triggers>

CommandAction (also uses System.Windows.Interactivity) can look like:

public class CommandAction : TriggerAction<UIElement>
{
    public static DependencyProperty CommandProperty = DependencyProperty.Register("Command", typeof(ICommand), typeof(CommandAction), null);
    public ICommand Command
    {
        get
        {
            return (ICommand)GetValue(CommandProperty);
        }
        set
        {
            SetValue(CommandProperty, value);
        }
    }


    public static DependencyProperty ParameterProperty = DependencyProperty.Register("Parameter", typeof(object), typeof(CommandAction), null);
    public object Parameter
    {
        get
        {
            return GetValue(ParameterProperty);
        }
        set
        {
            SetValue(ParameterProperty, value);

        }
    }

    protected override void Invoke(object parameter)
    {
        Command.Execute(Parameter);            
    }
}