Foolproof multiple validators on the same fields

Question

I currently use foolproof for that validation:

[RequiredIfNot(\"type\", 3, ErrorMessage = \"Please enter at least one value\")]
public int[] audites { get; set;          


        

Answer 1

The Foolproof.RequiredIfNotAttribute derives from Foolproof.ModelAwareValidationAttribute (which in turn derives from System.ComponentModel.DataAnnotation.ValidationAttribute). ModelAwareValidationAttribute is marked with [AttributeUsage(AttributeTargets.Property)]. Refer source code. By default the the AllowMultiple parameter of AttributeUsage is false which means that you can only apply the attribute once to a property. You have tried to apply it 3 times, hence the error.

Having it true and allowing it to be applied multiple times would possibly cause problems in setting the $.validator.methods and $.validator.unobtrusive.adapters functions used by unobtrusive validation.

You will need to use some other validation attributes or create your own ValidationAtribute that implements IClientValidatable, or rely on server side validation.