Validation Logic

Validation.cs

public override IEnumerable<RuleViolation> GetRuleViolations(int orgID)
{
    if (string.IsNullOrEmpty(FirstName))
        yield return new RuleViolation("First Name required", "FirstName");
    if (string.IsNullOrEmpty(LastName))
        yield return new RuleViolation("Last Name required", "LastName");
    if (string.IsNullOrEmpty(Name))
        yield return new RuleViolation("Name required", "Name");
    if (string.IsNullOrEmpty(Phone))
        yield return new RuleViolation("Phone required", "Phone");
}

public static void AddRuleViolations(this ModelStateDictionary modelState, IEnumerable<RuleViolation> errors)
{
    if (errors != null)
    {
        foreach (RuleViolation issue in errors)
        {
            modelState.AddModelError(issue.PropertyName, issue.ErrorMessage);
        }
    }
}