c# asp mvc ErrorMessage should contain another variable/property value

Question

I want to create an ErrorMessage containing another variable or property value in it. I want to keep it simple. So far this piece of code shows an error for the String.Format parameter. What is the best way to achieve it:

    public class MyClass
    {
        [RequiredIf("IsRequired", true, ErrorMessage=String.Format("The 'something' ({0}) is required because of: {1}", Something, CustomExplanation)]
        public string Something { get; set; }

        [Required]
        public bool IsRequired { get; set; }

        [Required]
        [StringLength(200, MinimumLength=20)]
        public string CustomExplanation { get; set; }
    }

I have already read this question and answer: string.Format in Data Annotation Validation Attributes That's ok, but maybe there is a workaround...

Answer 1

My suggestion for you is to use FluentValidator. This is very good library to reach you goals.

Link - http://fluentvalidation.codeplex.com/

You can solve your problem with code like this:

RuleFor(m => m.Something).When(m => m.IsRequired).WithMessage("Your message here.");

Please let me know in case of or if you'll have the questions.