public IEnumerable <PublicationDto> GetAllPublications(DateTime?loanDate) { IEnumerable <Publication> pubs; if (loanDate.HasValue) { pubs = _borrowRepo.GetAllPublicationsThatAreOnLoanByParticularDate((DateTime)loanDate); } else { pubs = _publicationRepo.GetAllPublications(); } return(pubs.Select(p => new PublicationDto(p))); }