Validate data using DataAnnotations with WPF & Entity Framework?

Question

Is there any way to validate using DataAnnotations in WPF & Entity Framework?

Answer 1

You can use the DataAnnotations.Validator class, as described here:

http://johan.driessen.se/archive/2009/11/18/testing-dataannotation-based-validation-in-asp.net-mvc.aspx

But if you're using a "buddy" class for the metadata, you need to register that fact before you validate, as described here:

http://forums.silverlight.net/forums/p/149264/377212.aspx

TypeDescriptor.AddProviderTransparent(   new AssociatedMetadataTypeTypeDescriptionProvider(typeof(myEntity),      typeof(myEntityMetadataClass)),    typeof(myEntity));  List<ValidationResult> results = new List<ValidationResult>(); ValidationContext context = new ValidationContext(myEntity, null, null) bool valid = Validator.TryValidateObject(myEntity, context, results, true); 

[Added the following to respond to Shimmy's comment]

I wrote a generic method to implement the logic above, so that any object can call it:

// If the class to be validated does not have a separate metadata class, pass // the same type for both typeparams. public static bool IsValid<T, U>(this T obj, ref Dictionary<string, string> 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<ValidationResult>();     Validator.TryValidateObject(obj, validationContext, validationResults, true);      if (validationResults.Count > 0 && errors == null)         errors = new Dictionary<string, string>(validationResults.Count);      foreach (var validationResult in validationResults)     {         errors.Add(validationResult.MemberNames.First(), validationResult.ErrorMessage);     }      if (validationResults.Count > 0)         return false;     else         return true; } 

In each object that needs to be validated, I add a call to this method:

[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<string, string> errors)     {         return this.IsValid<Employee, Metadata>(ref errors);         //If the Employee class didn't have a buddy class,         //I'd just pass Employee twice:         //return this.IsValid<Employee, Employee>(ref errors);     } }