更新分离的实体并有条件地更新NHibernate中的相关实体

Question

有没有办法将分离的实体更新回数据库，以及选择相关实体？这意味着我们必须

• 检查DB中是否存在分离的实体
• 如果它不存在，请添加
• 如果存在
  • 更新
  • 如果您想更新孩子，请执行此操作

问题是如果我们尝试对分离的实体做任何事情，NHibernate会抛出异常a different object with the same identifier value was already associated with the session！

有一个类的对象：

Class Parent
   int          ParentID
   ICollection  Children

因为对象以分离的形式出现，我们以前在Entity Framework中做的是：

// Try to load detached entity equivalent from DB
var entityInDB = LoadFromDB(entityDetached.Id)

// If it doesnt exist in db we need to add it
if (entityInDB == null) 
   AddNewEntity(entityDetached)
else
   // First update parent entity --- NHibernate doesnt have something similar?!
   // These lines need translation to NHibernate logic
   // BEGIN
   // (ERROR in nhibernate if we try SaveOrUpdate() !)
   _context.Entry(entityInDB).CurrentValues.SetValues(entityDetached);

   // Chose whether to update children or not
   if (AlsoUpdateChildren)
   {
       // Update child values-Add new children
       foreach (childDetached in entityDetached.Children)
       {
            SaveEntity(childDetached)
       }

       // Delete leftover children that didn't 
       // come back with the detached Parent
       // (ERROR in nhibernate!)
       foreach (LeftoverEntity in (entityInDB.Children AND NOT in entityDetached.Children) )
       {
            DeleteEntity(LeftoverEntity )
       }
   }
    //  END