How to override default required error message

Question

I have an old C# MVC 2.0 web application.

Whenever I use a [Required] attribute, the default validation error message goes:

The [whatever] field is required.

My problem is that the application isn't in English, so I basically have to change the attribute call to [Required(ErrorMessage = "Le champ [whatever] est requis.")] everywhere.

Is there a way to override the default error message so I only have to specify it when I want a specific message?

I'm looking for something like:

DefaultRequiredMessage = "Le champ {0} est requis.";

Answer 1

You can create a class and inherit it from RequiredAttribute. Something like this:

public class CustomRequired: RequiredAttribute
{
    public CustomRequired()
    {
        this.ErrorMessage = "Le champ est requis.";
    }
}

Or:

public class CustomRequired: RequiredAttribute
{
    public override string FormatErrorMessage(string whatever)
    {
        return !String.IsNullOrEmpty(ErrorMessage)
            ? ErrorMessage
            : $"Le champ {whatever} est requis.";
    }
}

You should use CustomRequired with your properties, rather than [Required].