MVC: Override default ValidationMessage

Question

In the world of MVC I have this view model...

public class MyViewModel{

[Required]
public string FirstName{ get; set; }    }

...and this s

Answer 1

This worked for me. Carefully read the comments inside the code. (Based on Chad's answer).

 // Keep the name the same as the original, it helps trigger the original javascript 
 // function for client side validation.

        public class RequiredAttribute : System.ComponentModel.DataAnnotations.RequiredAttribute, IClientValidatable
            {
                public RequiredAttribute()
                {
                    this.ErrorMessage = "Message" // doesnt get called again. only once.
                }

                public IEnumerable GetClientValidationRules(ModelMetadata metadata, ControllerContext context)
                {
                    yield return new ModelClientValidationRule
                    {
                        ErrorMessage = "Message", // this gets called on every request, so it's contents can be dynamic.
                        ValidationType = "required"
                    };
                }
            }