NHibernte CreateAlias for 2 multiply class - asp.net-mvc

Question

I have 3 classes: Book, Genre, Authors
public class Book {
public virtual int Id { get; set; }
public virtual string Name { get; set; }
public virtual string Description { get; set; }
public virtual int MfRaiting { get; set; }
public virtual int PageNumber { get; set; }
public virtual IList<Genre> Genres { get; set; }
public virtual Series Series { get; set; }
public virtual Mind Mind { get; set; }
public virtual IList<Author> Authors { get; set; }
public Book() {
Genres = new List<Genre>();
Authors = new List<Author>();
}
}
public class Genre {
public virtual int Id { get; set; }
public virtual string Name { get; set; }
public virtual IList<Book> Books { get; set; }
public Genre() {
Books=new List<Book>();
}
}
public class Author {
public virtual int Id { get; set; }
public virtual string Name { get; set; }
public virtual string SurName { get; set; }
public virtual string Biography { get; set; }
public virtual IList<Book> Books { get; set; }
public Author() {
Books=new List<Book>();
}
}
And his classMaps
public class BookMap : ClassMap<Book> {
public BookMap() {
Id(x => x.Id);
Map(x => x.Name);
HasManyToMany(x => x.Genres)
.Cascade.All()
.Table("Book_Genre");
HasManyToMany(x => x.Authors)
.Cascade.All()
.Table("Book_Author");
References(x => x.Series);
HasOne(x => x.Mind).Constrained();
}
}
public class GenreMap : ClassMap<Genre> {
public GenreMap() {
Id(x => x.Id);
Map(x => x.Name);
HasManyToMany(x => x.Books)
.Cascade.All()
.Inverse()
.Table("Book_Genre");
}
}
public class AuthorMap : ClassMap<Author> {
public AuthorMap() {
Id(x => x.Id);
Map(x => x.Name);
Map(x => x.SurName);
Map(x => x.Biography);
HasManyToMany(x => x.Books)
.Cascade.All()
.Inverse()
.Table("Book_Author");
}
}
When i try write in code
var criteria = session.CreateCriteria();
criteria.CreateAlias("Genres", "genre", JoinType.LeftOuterJoin);
it works well, but when i do so
public ActionResult Index()
{
var criteria = session.CreateCriteria<Book>();
criteria.CreateAlias("Genres", "genre", JoinType.LeftOuterJoin);
criteria.CreateAlias("Authors", "author", JoinType.LeftOuterJoin);
criteria.SetResultTransformer(new DistinctRootEntityResultTransformer());
}
i see exception Cannot simultaneously fetch multiple bags. How can I get result of that criteria?
Thank

Answer 1

I resolve this problem! I replace IList on ISet, and replace new List<"Class"> on new HashSet<"Class">
I read this problem here.
http://developer-should-know.tumblr.com/post/118012584847/jpa-fetching-strategies Only one collection that is fetched using JOIN strategy can be of type List, other collection must be of type Set. Otherwise an exception will be thrown:
HibernateException: cannot simultaneously fetch multiple bags