ASP.NET MVC DataAnnotation Required 1 from 3 property

Question

I am creating a project using ASP.NET MVC.

My model class looks like this:

public class CaseInformation
{
    public int Id { get; set; }

    public string CaseNumber { get; set; }
    public string RitNumber { get; set; }
    public string ApilNumber { get; set; }

    public DateTime Date { get; set; }

    public double CaseInvolvedRevenue { get; set; }
    public string CaseShortDescription { get; set; }
    public string CaseUpdateStatus { get; set; }

    public CompanyDetails CompanyDetails { get; set; }
    public int CompanyDetailsId { get; set; }
}

Here CaseNumber, RitNumber, ApilNumber only 1 is required. I can not put [Required] on all of them. How do I do that? Please help.

Answer 1

You can implement the IValidatableObject interface in your CaseInformation class itself. Here's what it would look like:

public class CaseInformation : IValidatableObject
{
    ...

    public IEnumerable<ValidationResult> Validate(ValidationContext ctx)
    {
        if (string.IsNullOrWhiteSpace(CaseNumber) &&
            string.IsNullOrWhiteSpace(RitNumber) &&
            string.IsNullOrWhiteSpace(ApilNumber))
        {
            yield return new ValidationResult("Your error message here.");
        }
    }
}

The Validate(ValidationContext) method is called by the framework when performing model validation. Here, we're just checking if all three values are missing and if so, we signal an error by returning a ValidationResult with a custom error message.