private IDataResult <List <BookDetailDto> > CheckParametres(int writerId, int publisherId, int categoryId) { if (writerId > 0 && publisherId > 0 && categoryId > 0) { return(new SuccessDataResult <List <BookDetailDto> >(_bookDal.GetBooksByFilter(b => b.WriterId == writerId && b.PublisherId == publisherId && b.CategoryId == categoryId))); } else if (writerId > 0 && publisherId > 0) { return(new SuccessDataResult <List <BookDetailDto> >(_bookDal.GetBooksByFilter(b => b.WriterId == writerId && b.PublisherId == publisherId))); } else if (categoryId > 0 && publisherId > 0) { return(new SuccessDataResult <List <BookDetailDto> >(_bookDal.GetBooksByFilter(b => b.CategoryId == categoryId && b.PublisherId == publisherId))); } else if (categoryId > 0 && writerId > 0) { return(new SuccessDataResult <List <BookDetailDto> >(_bookDal.GetBooksByFilter(b => b.CategoryId == categoryId && b.WriterId == writerId))); } else if (publisherId > 0) { return(new SuccessDataResult <List <BookDetailDto> >(_bookDal.GetBooksByFilter(b => b.PublisherId == publisherId))); } else if (categoryId > 0) { return(new SuccessDataResult <List <BookDetailDto> >(_bookDal.GetBooksByFilter(b => b.CategoryId == categoryId))); } else if (writerId > 0) { return(new SuccessDataResult <List <BookDetailDto> >(_bookDal.GetBooksByFilter(b => b.WriterId == writerId))); } else if (writerId == 0 && categoryId == 0 && publisherId == 0) { return(new SuccessDataResult <List <BookDetailDto> >(_bookDal.GetBookDetailsDto())); } return(new ErrorDataResult <List <BookDetailDto> >(Messages.ParametersNotFound)); }