How can I use the Data Validation Attributes in C# in a non-ASP.net context?

Question

I'd like to use the data validation attributes in a library assembly, so that any consumer of the data can validate it without using a ModelBinder (in a console application, for instance). How can I do it?

Answer 1

Actually this is pretty cool. I used it in a WFP validation implementation recently. Most people end up writing lots of code using reflection to iterate the attributes, but there's a built in function for this.

var vc = new ValidationContext(myObject, null, null);
return Validator.TryValidateObject(myObject, vc, null, true);

You can also validate attributes on a single named property. You can also optionally pass in a list in order to access the error messages :

var results = new List<ValidationResult>();
var vc = new ValidationContext(myObject, null, null) { MemberName = "UserName"};
var isValid = Validator.TryValidateProperty(value, vc, results);

// get all the errors
var errors = Array.ConvertAll(results.ToArray(), o => o.ErrorMessage);