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我想用标签保存图书。我的问题是,两本书中的相同标签被保存两次。NHibernate多对多保存重复数据
我的课:
public class Book
{
public virtual long ID { get; set; }
public virtual string Title { get; set; }
protected ICollection<Tag> _Tags = new List<Tag>();
public virtual ICollection<Tag> Tags { get { return _Tags; } set { _Tags = value; } }
}
public class Tag: IComparable
{
public virtual long ID { get; set; }
public virtual string Name { get; set; }
public override string ToString() { return Name; }
public virtual int CompareTo(object obj) { return string.Compare(Name, ((Tag)obj).Name); }
public override int GetHashCode() { return Name.GetHashCode(); }
public override bool Equals(object obj) { return Name.Equals(((Tag)obj).Name); }
}
的映射是:
<class name="Book" table="Books">
<id name="ID">
<generator class="identity"/>
</id>
<property name="Title"/>
<set name="Tags" table="BookTags" cascade="all-delete-orphan">
<key column ="BookID" />
<many-to-many class="Tag" column="TagID" />
</set>
</class>
<class name="Tag" table="Tags">
<id name="ID">
<generator class="identity"/>
</id>
<property name="Name"/>
</class>
我的代码是:
Book book;
book = new Book() { Title = "C#" };
book.Tags.Add(new Tag() { Name = "Programming" });
book.Tags.Add(new Tag() { Name = "Computer" });
PersistenceManager.Save(book);
book = new Book() { Title = "Android" };
book.Tags.Add(new Tag() { Name = "OS" });
book.Tags.Add(new Tag() { Name = "Computer" });
PersistenceManager.Save(book);
保存后,我想在表中具有三个标签标签:编程,计算机和Android。实际上,电脑被保存了两次。原因是因为我使用两个具有相同值的不同参考。
我厌倦了重写标记类中的CompareTo,GetHashCode和Equals,但没有成功。如果不同引用的值相同,是否有可能防止将值保存两次?