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    copied!<p>I supply you a sample code to help you. I have defined a ValidationRule to validate a texbox user input. The type of validation is performed according value of one enum parameter. Type of validation available are: user input cannot be empty, user input must be numeric, user input must be an IP address. A second parameter allows to specificy warning message displayed. As you know a variable for binding purposes should be a DependendyProperty, so here you find class with paramaters declaration.</p> <pre><code> public class ValidationParams : DependencyObject { // Dependency Properties public static readonly DependencyProperty MessageProperty = DependencyProperty.Register("Message", typeof(string), typeof(ValidationParams), new FrameworkPropertyMetadata(string.Empty)); public static readonly DependencyProperty ValidationTypeProperty = DependencyProperty.Register("ValidationType", typeof(FieldValidationRule.EnmValidationType), typeof(ValidationParams), new FrameworkPropertyMetadata(FieldValidationRule.EnmValidationType.FieldNotEmpty)); // Properties [Category("Message")] public string Message { get { return (string)GetValue(MessageProperty); } set { SetValue(MessageProperty, value); } } [Category("ValidationType")] public FieldValidationRule.EnmValidationType ValidationType { get { return (FieldValidationRule.EnmValidationType)GetValue(ValidationTypeProperty); } set { SetValue(ValidationTypeProperty, value); } } </code></pre> <p>Then here is the validationrule class:</p> <pre><code> public class FieldValidationRule : ValidationRule { public enum EnmValidationType { FieldNotEmpty, FieldNumeric, FieldIPAddress } // Local variables and objects private ValidationParams mParams = new ValidationParams(); public ValidationParams Params { get { return mParams; } set { mParams = value; } } // Override public override ValidationResult Validate(object value, System.Globalization.CultureInfo cultureInfo) { ValidationResult objResult = null; string sValue = value as string; objResult = new ValidationResult(true, null); switch (Params.ValidationType) { case EnmValidationType.FieldNotEmpty: if(string.IsNullOrEmpty(sValue) == true) objResult = new ValidationResult(false, Params.Message); break; case EnmValidationType.FieldNumeric: int iValue = 0; if(int.TryParse(sValue, out iValue) == false) objResult = new ValidationResult(false, Params.Message); break; case EnmValidationType.FieldIPAddress: IPAddress objValue = IPMatrix.CreateHostAddr(); if(IPAddress.TryParse(sValue, out objValue) == false) objResult = new ValidationResult(false, Params.Message); break; } return objResult; } } </code></pre> <p>And finally here is the XAML code:</p> <pre><code> &lt;TextBox Style="{DynamicResource FieldValue}" Grid.Column="1" IsReadOnly="False"&gt; &lt;TextBox.Text&gt; &lt;Binding Source="{StaticResource XmlItemChannel}" XPath="@Name" Mode="TwoWay" UpdateSourceTrigger="LostFocus"&gt; &lt;Binding.ValidationRules&gt; &lt;data:FieldValidationRule&gt; &lt;data:FieldValidationRule.Params&gt; &lt;data:ValidationParams Message="{DynamicResource ERR002}" ValidationType="FieldNotEmpty" /&gt; &lt;/data:FieldValidationRule.Params&gt; &lt;/data:FieldValidationRule&gt; &lt;/Binding.ValidationRules&gt; &lt;/Binding&gt; &lt;/TextBox.Text&gt; &lt;/TextBox&gt; </code></pre> <p>You can see that parameter Message is binded to a resource, but you can classically bind it too.</p>
 

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