Setting a property with an EventTrigger

Question

I want to be able to set a property with an EventTrigger, there\'s a number of problems with this.

1) EventTriggers only support Actions, so I must use a storyBoard

Answer 1

Just create your own action.

namespace WpfUtil
{
    using System.Reflection;
    using System.Windows;
    using System.Windows.Interactivity;


    /// 

    /// Sets the designated property to the supplied value. TargetObject
    /// optionally designates the object on which to set the property. If
    /// TargetObject is not supplied then the property is set on the object
    /// to which the trigger is attached.
    /// 
    public class SetPropertyAction : TriggerAction
    {
        // PropertyName DependencyProperty.

        /// 

        /// The property to be executed in response to the trigger.
        /// 
        public string PropertyName
        {
            get { return (string)GetValue(PropertyNameProperty); }
            set { SetValue(PropertyNameProperty, value); }
        }

        public static readonly DependencyProperty PropertyNameProperty
            = DependencyProperty.Register("PropertyName", typeof(string),
            typeof(SetPropertyAction));


        // PropertyValue DependencyProperty.

        /// 

        /// The value to set the property to.
        /// 
        public object PropertyValue
        {
            get { return GetValue(PropertyValueProperty); }
            set { SetValue(PropertyValueProperty, value); }
        }

        public static readonly DependencyProperty PropertyValueProperty
            = DependencyProperty.Register("PropertyValue", typeof(object),
            typeof(SetPropertyAction));


        // TargetObject DependencyProperty.

        /// 

        /// Specifies the object upon which to set the property.
        /// 
        public object TargetObject
        {
            get { return GetValue(TargetObjectProperty); }
            set { SetValue(TargetObjectProperty, value); }
        }

        public static readonly DependencyProperty TargetObjectProperty
            = DependencyProperty.Register("TargetObject", typeof(object),
            typeof(SetPropertyAction));


        // Private Implementation.

        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);
        }
    }
}

In this case I'm binding to a property called DialogResult on my viewmodel.

    
        
            
                
            
        
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