How can I set a property when an event happens? (selection changed on datagrid)

Question

I have a datagrid, I would like to change the backgrund of the datagrid when the selection changed event is fired.
I can not use data trigger, because is in the case that I expected a value, but in this case is when change, to any value.
An option is to use an event trigger, but all the examples that I have found is to use with an actions, and I just want to set a property.
How could I do that?
I am using MVVM pattern, so I would like to avoid the use in code-behind.
Thank so much.

Answer 1

You could use an event trigger and implement your own TriggerAction<T> that sets the background property. There is an example of how to create a custom TriggerAction available here:
http://stackoverflow.com/questions/942548/setting-a-property-with-an-eventtrigger.
The following example sets the Background property of the DataGrid to a red SolidColorBrush when the SelectionChanged event is fired. It should give you the idea:
<DataGrid x:Name="dgrid"
xmlns:local="clr-namespace:WpfApplication22">
<i:Interaction.Triggers>
<i:EventTrigger EventName="SelectionChanged">
<local:SetPropertyAction PropertyName="Background" TargetObject="{Binding ElementName=dgrid}">
<local:SetPropertyAction.PropertyValue>
<SolidColorBrush>Red</SolidColorBrush>
</local:SetPropertyAction.PropertyValue>
</local:SetPropertyAction>
</i:EventTrigger>
</i:Interaction.Triggers>
<DataGrid.Columns>
namespace WpfApplication22
public class SetPropertyAction : TriggerAction<FrameworkElement>
public string PropertyName
get { return (string)GetValue(PropertyNameProperty); }
set { SetValue(PropertyNameProperty, value); }
public static readonly DependencyProperty PropertyNameProperty
= DependencyProperty.Register("PropertyName", typeof(string),
typeof(SetPropertyAction));
public object PropertyValue
get { return GetValue(PropertyValueProperty); }
set { SetValue(PropertyValueProperty, value); }
public static readonly DependencyProperty PropertyValueProperty
= DependencyProperty.Register("PropertyValue", typeof(object),
typeof(SetPropertyAction));
public object TargetObject
get { return GetValue(TargetObjectProperty); }
set { SetValue(TargetObjectProperty, value); }
public static readonly DependencyProperty TargetObjectProperty
= DependencyProperty.Register("TargetObject", typeof(object),
typeof(SetPropertyAction));
protected override void Invoke(object parameter)
object target = TargetObject ?? AssociatedObject;
PropertyInfo propertyInfo = target.GetType().GetProperty(
PropertyName,
BindingFlags.Instance|BindingFlags.Public
|BindingFlags.NonPublic|BindingFlags.InvokeMethod);
propertyInfo.SetValue(target, PropertyValue);
For more information about how to hook up event triggers and handle events in MVVM, please refer to my blog post:
http://blog.magnusmontin.net/2013/06/30/handling-events-in-an-mvvm-wpf-application/
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