Johan Alkstål Johan Alkstål - 2 months ago 23x
ASP.NET (C#) Question

Why can't I use resources as ErrorMessage with DataAnnotations?

Why can't I do like this?

[Required(ErrorMessage = "*")]
[RegularExpression("^[a-zA-Z0-9_]*$", ErrorMessage = Resources.RegistrationModel.UsernameError)]
public string Username { get; set; }

What is the error message telling me?

An attribute argument must be a
constant expression , typeof
expression or array creation
expression of an attribute parameter


When you are using the ErrorMessage property only constant strings or string literal can be assigned to it.

Use the ErrorMessageResourceType and ErrorMessageResourceName instead to specity your resources.

    ErrorMessageResourceName= "UsernameError"

Note that the resources must be public (can be set in the resource editor).

Setting resource access to public