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].

Answer 2

Please perform the below operation to override default required error message:

• Create a custom adapter inheriting the RequiredAttributeAdapter as below :

---

public class YourRequiredAttributeAdapter : DataAnnotationsModelValidator<RequiredAttribute>
{
    public YourRequiredAttributeAdapter(ModelMetadata metadata, ControllerContext context, RequiredAttribute attribute)
        : base(metadata, context, attribute)
    {
        if (string.IsNullOrWhiteSpace(attribute.ErrorMessage)
            )
        {
            attribute.ErrorMessageResourceType ="Your resource file";
            attribute.ErrorMessageResourceName = "Keep the key name in resource file as "PropertyValueRequired";
        }
    }

}

• Register the Adapter in Global.asax Application_Start() as below:

---

DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(RequiredAttribute), typeof(YourRequiredAttributeAdapter));

---

• Resource File Configuration: