how to achieve Binding inside ValidationRules ?

See more:

C#

XAML

WPF

validation

Binding

i want to push some view model properties into validation class

i learnt that its difficult but possible so i have tried the fallowing

have declared a resource like the fallowing

<FrameworkElement x:Key="DataContextBridge" DataContext="{Binding Path=DataContext, RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}" />

and here is the validationrule

<TextBox x:Name="textBoxConferenceName" >
<Binding Path="CurrentConference.ConferenceName" >
<Binding.ValidationRules>
<helper:ConferenceNameValidationRule ErrorMessage="ConferenceName Already Exists">
<helper:ConferenceNameUniqueValidationRule.Data>
<helper:ConferenceNameUniqueValidationRuleData ConferenceCollection="{Binding Path=DataContext.ConferenceCollection, Source={StaticResource DataContextBridge}}"                                                                               ChoosenConference="{Binding Path=DataContext.SelectedConference, Source={StaticResource DataContextBridge}}" />
</helper:ConferenceNameUniqueValidationRule.Data> 
</helper:ConferenceNameUniqueValidationRule>
</Binding.ValidationRules>
</Binding>
</TextBox>

and here is the ConferenceNameValidationRule and ConferenceNameUniqueValidationRuleData C# classes

public class ConferenceNameUniqueValidationRule:ValidationRule
    {
        public ConferenceNameUniqueValidationRule()
        {
            _data = new ConferenceNameUniqueValidationRuleData();
        }

        private ConferenceNameUniqueValidationRuleData _data;
        public ConferenceNameUniqueValidationRuleData Data
        {
            get { return _data; }
            set { _data = value; }
        }

        private string _errorMessage;
        public string ErrorMessage
        {
            get { return _errorMessage; }
            set { _errorMessage = value; }
        }

        public override ValidationResult Validate(object value, CultureInfo cultureInfo)
        {
            if (Data != null && (Data.ChoosenConference != null && Data.ConferenceCollection != null))
            {
                if (Data.ConferenceCollection.Where(c => c.ConferenceID != Data.ChoosenConference.ConferenceID).Any(i => i.ConferenceName == Data.ChoosenConference.ConferenceName.Trim()))
                {
                    return new ValidationResult(false,ErrorMessage);
                }
            }
            return ValidationResult.ValidResult;
        }
    }

public class ConferenceNameUniqueValidationRuleData:DependencyObject
    {
        public ObservableCollectionEx<Conference> ConferenceCollection
        {
            get { return (ObservableCollectionEx<Conference>)GetValue(ConferenceCollectionDp); }
            set { SetValue(ConferenceCollectionDp, value); }
        }

        public Conference ChoosenConference
        {
            get { return (Conference)GetValue(ChoosenConferenceDp); }
            set { SetValue(ChoosenConferenceDp, value); }
        }

        public static readonly DependencyProperty ChoosenConferenceDp = DependencyProperty.Register(
            "ChoosenConference", typeof(Conference), typeof(ConferenceNameUniqueValidationRuleData), new PropertyMetadata(null));

        public static readonly DependencyProperty ConferenceCollectionDp = DependencyProperty.Register(
            "ConferenceCollection", typeof(ObservableCollectionEx<Conference>), typeof(ConferenceNameUniqueValidationRuleData), new PropertyMetadata(null));
    }

so here i am using the datacontext object inside the validation class and i am also usind dependency object

and a i am getting the fallowing problem

the output shows fallowing error
Cannot find source for binding with reference 'RelativeSource FindAncestor, AncestorType='System.Windows.Controls.UserControl', AncestorLevel='1''. BindingExpression:Path=DataContext; DataItem=null; target element is 'FrameworkElement' (Name=''); target property is 'DataContext' (type 'Object')