当经过Automapper时，NHibernate加载的树会命中数据库

我遇到了一个奇怪的NHibernate和Automapper问题。我不确定是谁的错，但我现在挣扎了一整天，我似乎不知道为什么

以下是我的Nhibernate映射文件：

Navigation.hbm.xml

<id name="ID" column="NavigationID">
  <generator class="identity"></generator>
</id>

<property name="IsDefault"/>
<property name="RoleType" column="RoleTypeID" />

<bag  name="Items" cascade="save-update" inverse="true" lazy="false" fetch="join">
  <key column="NavigationID"/>
  <one-to-many class="NavigationItem"/>
</bag>

然后，当Automapper发挥作用时，将生成这些查询的列表，只有p0参数不同（从1到12…没有父项的项数）

这是从NHProf应用程序中获取的，希望对您有所帮助

谢谢,，

---

Cosmin

我认为AutoMapper正在递归地映射您的类。如果是这种情况，则可以使用指定映射的最大深度

Mapper.CreateMap<TSource, TDestination>().MaxDepth(2); // or 1, or 3, or whatever

Mapper.CreateMap（）.MaxDepth（2）；//或者1，或者3，或者别的什么

Hi Cosmin，你能发布执行的SQL吗？你好，James，我已经用生成的SQL编辑了这个问题。是的，有，但我想要这个。问题是，我希望AutoMapper递归地映射它们，但不命中数据库。信息都在那里，由NHIbernate加载。我的问题是，为什么当AutoMapper遍历对象层次结构时，NHibernate认为他需要点击数据库？因此调用navigation.Items[0]。Items[0]不会触发数据库查询？不确定，但我不认为每个NavigationItem.Items集合都是从您的查询映射的。也许在包上指定批量大小可以通过批处理请求来提高性能。我目前正在处理一个NHibernate项目，该项目在我的实体中有很多层次关系，我发现如果不使用单独的多对多联接表，就很难用一个查询加载所有集合的整个聚合根，就像在这篇博文中所说的，这都是关于NHibernate延迟加载的。Automapper尝试映射所有属性（引用），以便通过反射命中对象上具有代理的一些属性。之后，nHibernate认为您需要该对象或集合，它会延迟加载数据。是的，但问题是他的模型是分层的，因此AutoMapper会递归加载未加载的整个图形属性。即使他正在查询所有实体，但这并不意味着它们之间的所有关系都已设置。

ISession session = SessionProvider.Instance.CurrentSession;

            using (transaction = session.BeginTransaction())
            {
                var navigation = session.QueryOver<Navigation>()
                    .Where(x => x.IsDefault && x.RoleType == null)
                    .TransformUsing(new NHibernate.Transform.RootEntityResultTransformer())
                    .SingleOrDefault();

                transaction.Commit();
                return navigation;
            }

public class NavigationModel
{
    public List<NavigationItemModel> Items { get; set; }

    public NavigationModel()
    {
        Items = new List<NavigationItemModel>();
    }
}

public class NavigationItemModel
{
    public string PageName { get; set; }
    public string Url { get; set; }
    public bool Selected { get; set; }

    public NavigationItemModel Parent { get; set; }
    public List<NavigationItemModel> Items { get; set; }
}

AutoMapper.Mapper
            .CreateMap<NavigationItem, NavigationItemModel>()
 // IF I REMOVE THE NEXT LINE, IT HITS THE DATABASE FOR EACH SUB-ITEM of the NavigationItem.Items
            .ForMember(m => m.Items, o => o.Ignore()); 

        AutoMapper.Mapper
            .CreateMap<Navigation, NavigationModel>();

SELECT this_.NavigationID             as Navigati1_7_2_,
   this_.IsDefault                as IsDefault7_2_,
   this_.RoleTypeID               as RoleTypeID7_2_,
   items2_.NavigationID           as Navigati5_4_,
   items2_.NavigationItemID       as Navigati1_4_,
   items2_.NavigationItemID       as Navigati1_4_0_,
   items2_.ShowInMenu             as ShowInMenu4_0_,
   items2_.[Order]                as column3_4_0_,
   items2_.PageID                 as PageID4_0_,
   items2_.NavigationID           as Navigati5_4_0_,
   items2_.ParentNavigationItemID as ParentNa6_4_0_,
   page3_.PageID                  as PageID8_1_,
   page3_.Name                    as Name8_1_,
   page3_.Title                   as Title8_1_,
   page3_.Description             as Descript4_8_1_,
   page3_.URL                     as URL8_1_
FROM   Navigation this_
   left outer join NavigationItem items2_
     on this_.NavigationID = items2_.NavigationID
   left outer join Page page3_
     on items2_.PageID = page3_.PageID
WHERE  (this_.IsDefault = 1 /* @p0 */
    and this_.RoleTypeID is null)

SELECT items0_.ParentNavigationItemID as ParentNa6_2_,
   items0_.NavigationItemID       as Navigati1_2_,
   items0_.NavigationItemID       as Navigati1_4_1_,
   items0_.ShowInMenu             as ShowInMenu4_1_,
   items0_.[Order]                as column3_4_1_,
   items0_.PageID                 as PageID4_1_,
   items0_.NavigationID           as Navigati5_4_1_,
   items0_.ParentNavigationItemID as ParentNa6_4_1_,
   page1_.PageID                  as PageID8_0_,
   page1_.Name                    as Name8_0_,
   page1_.Title                   as Title8_0_,
   page1_.Description             as Descript4_8_0_,
   page1_.URL                     as URL8_0_
FROM   NavigationItem items0_
   left outer join Page page1_
     on items0_.PageID = page1_.PageID
WHERE  items0_.ParentNavigationItemID = 1 /* @p0 */

Mapper.CreateMap<TSource, TDestination>().MaxDepth(2); // or 1, or 3, or whatever