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POBinding on a Non-UIElement
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  1. POBinding on a Non-UIElement
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    copied!<p>I am having problems with Binding. Since <code>RelativeSource</code> needs the visual tree to travel up and find the desired Ancestor, you are only allowed to use it on an <code>UIElement</code> but I am trying to do a <code>RelativeSource</code> binding on an Non-UIElement, such as is a ValidationRule, which as you all know isnt inside the <code>VisualTree</code> nor its <code>UIElement</code>. As you can expect the binding breaks. <code>RelativeSource</code> couldn't be found because like i said there is no <code>VisualTree</code> or <code>LogicalTree</code> available. I need to make it work though.</p> <p>Here is an example of XAML:</p> <pre><code>&lt;StackPanel DataContext{Binding}&gt; &lt;Grid&gt; &lt;ContentControl Content{Binding MVPart1&gt; &lt;TextBox&gt; &lt;TextBox.Text&gt; &lt;Binding Path="VMPart1Property1"&gt; &lt;Binding.ValidationRules&gt; &lt;my:MyValidationRule&gt; &lt;my:ValidationRule.DOC&gt; &lt;my:DepObjClass DepProp={Binding Path=DataContext, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type StackPanel}}}/&gt; &lt;/my:ValidationRule.DOC&gt; &lt;/Binding.ValidationRules&gt; &lt;/Binding&gt; &lt;/TextBox.Text&gt; &lt;/TextBox&gt; &lt;/ContentControl&gt; &lt;/Grid&gt; &lt;/StackPanel&gt; </code></pre> <p>So basically MyValidationRule is derivering from ValidationRule class, but thats not UIElement nor DependencyObject and therefore I had to create a class which derivates from DependencyObject called DepObjClass to be able to write down the xaml binding expression.</p> <p>Here is code:</p> <pre><code>public class MyValidationRule : ValidationRule { public DepObjClass DOC { get; set; } public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo) { string text = value as string; if (!string.IsNullOrEmpty(text)) { return new ValidationResult(true, string.Empty); } return new ValidationResult(false, "Not working blahhh"); } } public class DepObjClass : DependencyObject { public object DepProp { get { return (object)GetValue(DepPropProperty); } set { SetValue(DepPropProperty, value); } } public static DependencyProperty DepPropProperty = DependencyProperty.Register(typeof(object), typeof(DepObjClass)......); } </code></pre> <p>Now to sum up. MyValidatonRule is not UIElement its not DependencyObject but it has a property of a type that is, hence why the xaml binding expression compiles.</p> <p>When I run the application the binding itself isnt working because StackPanel couldnt be found because ValidationRule doesnt have VisualTree nor my validation rule participates in Logical or Visual Tree. </p> <p>The question is how do I make such case work, how to find StackPanel from an Non-UIElement such as my ValidationRule?</p> <p>I appologize for my code not comipiling but I hope you can understand what I am trying to do. I am giving 50 points to you guys for the right answer. </p>
 

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