设计了具有实体框架的数据访问层和PackageInstance对象的示例POCO结构
public class PackageInstance
{
public virtual long PackageInstanceId {set;get;}
public virtual boolean IsDeleted {set;get;}
public virtual List<Session> Sessions {set;get;}
}
public class Session
{
public virtual long SessionId {set;get;}
public virtual long PackageInstanceId {set;get;}
public virtual boolean IsDeleted {set;get;}
public virtual List<Note> Notes {set;get;}
}
public class Note
{
public virtual long NoteId {set;get;}
public virtual long SessionId {set;get;}
public virtual boolean IsDeleted {set;get;}
public virtual List<Documents> Document {set;get;}
}
我需要在单个方法调用中加载PackageInstance对象及其子对象,而不是分别加载每个对象。
var packageInstanceDB = entity.PackageInstances.First(p => p.PurchaseSessionId == purhcaseSessionId);
//There is a DB call happening here to load the Session.
packageInstanceDB.Sessions.Where(s=>!s.IsActive).ForEach(s =>
{
//Again there is a DB call happening here to load the associated session notes.
s.Notes.Where(sn => !sn.IsDeleted).ToList().ForEach(sd=>
//Again there is a DB call happening here to load the associated note documents.
sd.Documents.Where(doc=>!doc.IsDeleted));
});
这里如何消除多个DB调用?
免责声明:我是Entity Framework Plus项目的所有者
EF + Query IncludeFilter功能允许过滤相关实体。它支持EF5
var packageInstanceDB = entity.PackageInstances
.IncludeFilter(x => x.Sessions)
.IncludeFilter(x => x.Sessions.Select(y => y.Notes.Where(sn => !sn.IsDeleted)))
.IncludeFilter(x => x.Sessions.SelectMany(y => y.Notes.Where(sn => !sn.IsDeleted)).Select(z => z.Documents.Where(sn => !sn.IsDeleted)))
.First(p => p.PackageInstanceId == purhcaseSessionId);
注意:必须包含每个路径