How do I specify error member key in ASP.NET MVC CustomValidation?

Question

I'm trying to add CustomValidation and make it return error for

Html.ValidationMessageFor(m => m.SubleaseCompany)

[CustomValidation(typeof(CreateSpaceModelValidation), "ValidateCreateSpaceModel")]
public class CreateSpaceModel
{
    public Building Building { get; set; }
    public Space Space { get; set; }

    public string SubleaseCompany { get; set; }
}

public class CreateSpaceModelValidation
{
    public static ValidationResult ValidateCreateSpaceModel(CreateSpaceModel model)
    {
        return new ValidationResult("You should specify Sublease Contact", new[] { "SubleaseCompany" }).;
    }
}

I'm using second argument for ValidationResult constructor (memberNames) but this doesn't seem to work.

Answer 1

Looks like the MVC team never implemented the functionality for the MemberNames parameter. See the following exert from.... http://devtrends.co.uk/blog/the-complete-guide-to-validation-in-asp.net-mvc-3-part-2

In some situations, you might be tempted to use the second constructor overload of ValidationResult that takes in an IEnumerable of member names. For example, you may decide that you want to display the error message on both fields being compared, so you change the code to this:

return new ValidationResult(
    FormatErrorMessage(validationContext.DisplayName),

new[] { validationContext.MemberName, OtherProperty });

If you run your code, you will find absolutely no difference. This is because although this overload is present and presumably used elsewhere in the .NET framework, the MVC framework completely ignores ValidationResult.MemberNames.