public CallValidator()
        {
            RuleFor(x => x.ContactId).GreaterThan(0).WithMessage("'{PropertyName}' is not valid.");
            RuleFor(x => x.Date).NotEmpty();

            RuleSet("create", () =>
            {
                RuleFor(x => x)
                .Must(x => CallService.GetCountByContactId(x.ContactId) < 10)
                .WithMessage("The maximum limit has been reached. No more can be added.");
            });
        }