NHibernate级联保存

Question

这是尝试在Comment.BlogArticleID中插入null.

出现以下GenericADOException:"无法插入:[NHibernate__OneToMany.BO.Comment] [SQL:INSERT INTO注释(名称)VALUES(？);选择SCOPE_IDENTITY()]"

出现以下内部异常:"无法将值NULL插入列'BlogArticleID',表'Relationships_Test_OneToMany.dbo.Comment';列不允许空值.INSERT失败.\ r \n语句已终止."

我需要一个单向映射.提供的答案还在谈论双向映射.

NHibernate级联保存是否适用于本机ID生成器？

数据库表:

BlogArticle {ID,Name},如果是ID,则Identitity = true.

注释{ID,Name,BlogArticleID},如果是ID,则Identitity = true.

Comment.hbm.xml

<hibernate-mapping
  xmlns="urn:nhibernate-mapping-2.2"
  assembly="NHibernate__OneToMany.BO"
  namespace="NHibernate__OneToMany.BO"
  default-access="property">

  <class name="Comment" table="Comment">
    <id name="ID">
      <generator class="native" />
    </id>

    <property name="Name" />
  </class>
</hibernate-mapping>

public class Comment
    {
        private int _id;
        public virtual int ID
        {
            get { return _id; }
            set { _id = value; }
        }

        public Comment()
        {
        }

        public Comment(string name)
        {
            this._name = name;
        }

        private string _name;
        public virtual string Name
        {
            get { return _name; }
            set { _name = value; }
        }   
    }

BlogArticle.hbm.xml

<hibernate-mapping 
  xmlns="urn:nhibernate-mapping-2.2"
  namespace="NHibernate__OneToMany.BO"
  assembly="NHibernate__OneToMany.BO"
  default-access="property">
  <class name="BlogArticle"  table="BlogArticle">
    <id name="ID">
      <generator class="native" />
    </id>

    <property name="Name" column="Name" />

    <bag name="Comments" cascade="all" >
      <key column="BlogArticleID" />
      <one-to-many class="Comment" />
    </bag>
  </class>
</hibernate-mapping>


public class BlogArticle
    {
        private int _id;
        public virtual int ID
        {
            get { return _id; }
            set { _id = value; }
        }

        private string _name;
        public virtual string Name
        {
            get { return _name; }
            set { _name = value; }
        }

        private IList _depts;
        public virtual IList Comments
        {
            get { return _depts; }
            set { _depts = value; }
        }   
    }

主要

class Program
{
    static void Main(string[] args)
    {
        BlogArticle ba = new BlogArticle();
        ba.Name = "Humanity";
        ba.Comments = new List<Comment>();
        ba.Comments.Add(new Comment("Comm1"));
        ba.Comments.Add(new Comment("Comm2"));
        ba.Comments.Add(new Comment("Comm3"));

        Repository<BlogArticle> rep = new Repository<BlogArticle>();
        rep.Save(ba);
    }
}

知识库

public class Repository<T> : IRepository<T>
    {
        ISession _session;

        public Repository()
        {
            _session = SessionFactoryManager.SessionFactory.OpenSession();
        }

        private void Commit()
        {
            if (_session.Transaction.IsActive)
            {
                _session.Transaction.Commit();
            }
        }

        private void Rollback()
        {
            if (_session.Transaction.IsActive)
            {
                _session.Transaction.Rollback();
                //_session.Clear();
            }
        }

        private void BeginTransaction()
        {
            _session.BeginTransaction();
        }

        public void Save(T obj)
        {
            try
            {
                this.BeginTransaction();

                _session.Save(obj);                

                this.Commit();
            }
            catch (Exception ex)
            {
                this.Rollback();

                throw ex;
            }            
        }

        void IRepository<T>.Save(IList<T> objs)
        {
            try
            {
                this.BeginTransaction();

                for (Int32 I = 0; I < objs.Count; ++I)
                {
                    _session.Save(objs[I]);
                }

                this.Commit();
            }
            catch (Exception ex)
            {
                this.Rollback();

                throw ex;
            }
        }

        void IRepository<T>.Update(T obj)
        {
            try
            {
                this.BeginTransaction();

                _session.Update(obj);

                this.Commit();
            }
            catch (Exception ex)
            {
                this.Rollback();

                throw ex;
            }
        }

        void IRepository<T>.Update(IList<T> objs)
        {
            try
            {
                this.BeginTransaction();

                for (Int32 I = 0; I < objs.Count; ++I)
                {
                    _session.Update(objs[I]);
                }

                this.Commit();
            }
            catch (Exception ex)
            {
                this.Rollback();

                throw ex;
            }
        }

        void IRepository<T>.Delete(T obj)
        {
            try
            {
                this.BeginTransaction();

                _session.Delete(obj);

                this.Commit();
            }
            catch (Exception ex)
            {
                this.Rollback();

                throw ex;
            }  
        }

        void IRepository<T>.Delete(IList<T> objs)
        {
            try
            {
                this.BeginTransaction();

                for (Int32 I = 0; I < objs.Count; ++I)
                {
                    _session.Delete(objs[I]);
                }

                this.Commit();
            }
            catch (Exception ex)
            {
                this.Rollback();

                throw ex;
            }
        }

        T IRepository<T>.Load<T>(object id)
        {
            return _session.Load<T>(id);
        }

        public IList<T> Get<T>(int pageIndex, int pageSize)
        {
            ICriteria criteria = _session.CreateCriteria(typeof(T));
            criteria.SetFirstResult(pageIndex * pageSize);
            if (pageSize > 0)
            {
                criteria.SetMaxResults(pageSize);
            }
            return criteria.List<T>();
        }

        public T Get<T>(object id)
        {
            return _session.Get<T>(id);
        }

        public IList<T> Get<T>()
        {
            return Get<T>(0, 0);
        }

        public IList<T> Get<T>(string propertyName, bool Ascending)
        {
            Order cr1 = new Order(propertyName, Ascending);

            IList<T> objsResult = _session.CreateCriteria(typeof(T)).AddOrder(cr1).List<T>();

            return objsResult;
        }

        public IList<T> Find<T>(IList<string> strs)
        {
            System.Collections.Generic.IList<NHibernate.Criterion.ICriterion> objs = new System.Collections.Generic.List<ICriterion>();
            foreach (string s in strs)
            {
                NHibernate.Criterion.ICriterion cr1 = NHibernate.Criterion.Expression.Sql(s);
                objs.Add(cr1);
            }
            ICriteria criteria = _session.CreateCriteria(typeof(T));
            foreach (ICriterion rest in objs)
                _session.CreateCriteria(typeof(T)).Add(rest);

            criteria.SetFirstResult(0);
            return criteria.List<T>();
        }

        public void Detach(T item)
        {
            _session.Evict(item);
        }        
    }

Answer 1

关联类的键列(Comment.BlogArticleID)必须在数据库中可为空.NHibernate将插入将此列留空的行,然后执行更新以设置密钥.

将not-null ="true"添加到key元素将不起作用,因为此属性仅由架构导出工具使用.

请注意,失败的插入包括为新子行生成的标识的选择.