public SignOverValidator(IProcessQueries queryProcessor) { CascadeMode = CascadeMode.StopOnFirstFailure; RuleFor(p => p.EmailAddress) // cannot be empty .NotEmpty() .WithMessage(FailedBecauseEmailAddressWasEmpty) // must be in db .Must(p => ValidateUser.NameMatchesEntity(p, queryProcessor)) .WithMessage(FailedBecauseEmailAddressMatchedNoUser, p => p.EmailAddress) ; }