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    copied!<p>You can use the DataAnnotations.Validator class, as described here:</p> <p><a href="http://johan.driessen.se/archive/2009/11/18/testing-dataannotation-based-validation-in-asp.net-mvc.aspx" rel="noreferrer">http://johan.driessen.se/archive/2009/11/18/testing-dataannotation-based-validation-in-asp.net-mvc.aspx</a></p> <p>But if you're using a "buddy" class for the metadata, you need to register that fact before you validate, as described here:</p> <p><a href="http://forums.silverlight.net/forums/p/149264/377212.aspx" rel="noreferrer">http://forums.silverlight.net/forums/p/149264/377212.aspx</a></p> <pre><code>TypeDescriptor.AddProviderTransparent( new AssociatedMetadataTypeTypeDescriptionProvider(typeof(myEntity), typeof(myEntityMetadataClass)), typeof(myEntity)); List&lt;ValidationResult&gt; results = new List&lt;ValidationResult&gt;(); ValidationContext context = new ValidationContext(myEntity, null, null) bool valid = Validator.TryValidateObject(myEntity, context, results, true); </code></pre> <p><strong>[Added the following to respond to Shimmy's comment]</strong></p> <p>I wrote a generic method to implement the logic above, so that any object can call it:</p> <pre><code>// If the class to be validated does not have a separate metadata class, pass // the same type for both typeparams. public static bool IsValid&lt;T, U&gt;(this T obj, ref Dictionary&lt;string, string&gt; errors) { //If metadata class type has been passed in that's different from the class to be validated, register the association if (typeof(T) != typeof(U)) { TypeDescriptor.AddProviderTransparent(new AssociatedMetadataTypeTypeDescriptionProvider(typeof(T), typeof(U)), typeof(T)); } var validationContext = new ValidationContext(obj, null, null); var validationResults = new List&lt;ValidationResult&gt;(); Validator.TryValidateObject(obj, validationContext, validationResults, true); if (validationResults.Count &gt; 0 &amp;&amp; errors == null) errors = new Dictionary&lt;string, string&gt;(validationResults.Count); foreach (var validationResult in validationResults) { errors.Add(validationResult.MemberNames.First(), validationResult.ErrorMessage); } if (validationResults.Count &gt; 0) return false; else return true; } </code></pre> <p>In each object that needs to be validated, I add a call to this method:</p> <pre><code>[MetadataType(typeof(Employee.Metadata))] public partial class Employee { private sealed class Metadata { [DisplayName("Email")] [Email(ErrorMessage = "Please enter a valid email address.")] public string EmailAddress { get; set; } } public bool IsValid(ref Dictionary&lt;string, string&gt; errors) { return this.IsValid&lt;Employee, Metadata&gt;(ref errors); //If the Employee class didn't have a buddy class, //I'd just pass Employee twice: //return this.IsValid&lt;Employee, Employee&gt;(ref errors); } } </code></pre>
 

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