Question

我有以下表结构

Author[AuthorId,AuthorName];
Book [BookId, BookName, AuthorId];

已经为F.N映射创建了以下类

public class Author
{
    public virtual int AuthorId         { get; set; }
    public virtual string AuthorName    { get; set; }

    public IList<Book> Book { get; set; }
}

public class AuthorDataMap : ClassMap<Auther>
{
    public MaisonUserDataMap()
    {
        Table("author");
        Id(x => x.AuthorId).Column("authorID");
        Map(x => x.AuthorName).Column("authorName");

        HasMany<MonsterData>(p => p.monsterData)
        .KeyColumn("authorID")
        .PropertyRef("AuthorId").Inverse();
}


public class Book
{
    public virtual int BookId           { get; set; }
    public virtual string BookName      { get; set; }
    public virtual int AuthorId         { get; set; }

    public virtual Author Author { get; set; }

        public Book()
        {
            Author = new Author();
        }
}


class BookMap : ClassMap<Book>
{
        public BookMap()
        {
            Table("book");
            Id(x => x.BookId).Column("bookId");
            Map(x => x.BookName).Column("bookName");
            Map(x => x.AuthorId).Column("authorId");

            References(x => x.Author);
        }
}

使用以下NH查询，它将返回每个作者的单个对象及其相关书籍列表

var authorList = session.CreateCriteria<Auther>("AuthorList").Add(Restrictions.Eq("AuthorList.AuthorId", 1)).List<Author>(); // working

Console.WriteLine("AuthorList Count :" + authorList.Count);
foreach (var item in authorList)
{

    foreach (var k in item.book)
    {
        Console.WriteLine("BookId :" + k.bookId);
    }

}

现在我想获得具有作者详细信息的书籍对象列表。（与上述相反）。我尝试使用以下代码执行此操作，但它没有返回任何作者详细信息

var bookList = session.CreateCriteria<Book>("Book").Add(Restrictions.Eq("Book.AuthorId", 1)).List<Book>();
Console.WriteLine("BookList Count :" + bookList.Count);
foreach (var item in bookList)
{
    Console.WriteLine("BookId :" + item.bookId);
    Console.WriteLine("AuthorName :" + item.Author.authorName);
}

如果有人知道怎么做，请告诉我。感谢

Answer 1

如果我们想要使用一列映射到TWO属性，映射应如下所示：

public BookMap()
{
    Table("book");
    Id(x => x.BookId).Column("bookId");
    Map(x => x.BookName).Column("bookName");

    // authorId column for both
    Map(x => x.AuthorId)
       .Column("authorId")
       .Not.Insert()
       .Not.Update()
       ;

    References(x => x.Author, "authorId");
}

所以，现在我们明确地说流利的NHibernate - 有“authorId”的值类型和引用类型表示。其中一个必须是readonly - 正确生成INSERT和UPDATE。

现在这个查询可以正常工作

var bookList = session
  .CreateCriteria<Book>("Book")
  .Add(Restrictions.Eq("Book.AuthorId", 1))
  .List<Book>();

Console.WriteLine("BookList Count :" + bookList.Count);
foreach (var item in bookList)
{
    Console.WriteLine("BookId :" + item.bookId);
    Console.WriteLine("AuthorName :" + item.Author.authorName);
}

注意，另一方（作者）可以让HasMany现在定义没有属性ref

HasMany(a => a.Books)
    .KeyColumn("authorID")
    //.PropertyRef("AuthorId") // there will be Author reference
    .Inverse();

使用Fluent Nhibernate加入表

1 个答案: