如何在NHibernate中使用QUeryOver投影列表

Question

當談到NHibernate中的QueryOver時，我有點迷惑（或者更可能）。

我想是這樣的：

_session.QueryOver<Task>() 
    .Where(x => x.Category == category) 
    .Fetch(x => x.SubTasks).Eager 
    .Select(
     x => x.Id, 
     x => x.DisplayName, 
     x => x.SubTasks) 
    .List<object[]>(); 

哪我希望會回到我對象的數組列表與我的ID，顯示名稱和某種即時加載子任務的集合。

相反，我得到以下異常：

NHibernate.Exceptions.GenericADOException: could not execute query 
[ SELECT this_.Id as y0_, this_.DisplayName as y1_, this_.Id as y2_ FROM [Task] this_ WHERE this_.Category = @p0 ] 
Positional parameters: #0>Internal 
[SQL: SELECT this_.Id as y0_, this_.DisplayName as y1_, this_.Id as y2_ FROM [Task] this_ WHERE this_.Category = @p0] ---> System.IndexOutOfRangeException: Index was outside the bounds of the array. 
    at NHibernate.Loader.Criteria.CriteriaLoader.GetResultColumnOrRow(Object[] row, IResultTransformer resultTransformer, IDataReader rs, ISessionImplementor session) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Loader\Criteria\CriteriaLoader.cs:line 111 
    at NHibernate.Loader.Loader.DoQuery(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Loader\Loader.cs:line 479 
    at NHibernate.Loader.Loader.DoQueryAndInitializeNonLazyCollections(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Loader\Loader.cs:line 243 
    at NHibernate.Loader.Loader.DoList(ISessionImplementor session, QueryParameters queryParameters) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Loader\Loader.cs:line 1694 
    --- End of inner exception stack trace --- 
    at NHibernate.Loader.Loader.DoList(ISessionImplementor session, QueryParameters queryParameters) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Loader\Loader.cs:line 1711 
    at NHibernate.Loader.Loader.ListIgnoreQueryCache(ISessionImplementor session, QueryParameters queryParameters) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Loader\Loader.cs:line 1601 
    at NHibernate.Loader.Criteria.CriteriaLoader.List(ISessionImplementor session) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Loader\Criteria\CriteriaLoader.cs:line 74 
    at NHibernate.Impl.SessionImpl.List(CriteriaImpl criteria, IList results) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Impl\SessionImpl.cs:line 1928 
    at NHibernate.Impl.CriteriaImpl.List(IList results) in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Impl\CriteriaImpl.cs:line 265 
    at NHibernate.Impl.CriteriaImpl.List[T]() in d:\CSharp\NH\NH\nhibernate\src\NHibernate\Impl\CriteriaImpl.cs:line 277 
    at Codehouse.TimeRegistration.Web.Controllers.TimeRegistrationAjax.TimeRegistrationGetTasksController.Execute(String category) in E:\TfsSource\Codehouse Time Registration Beetle\Main\Source\Codehouse.TimeRegistration.Web.Controllers\TimeRegistrationAjax\TimeRegistrationGetTasksControllers.cs:line 26 
    at lambda_method(Closure , ControllerBase , Object[]) 
    at System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) 
    at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) 
    at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass15.<InvokeActionMethodWithFilters>b__12() 
    at System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) 

我花了一個鐘頭看好谷歌，但無濟於事 - 因此，任何形式的幫助/指針將不勝感激。

Answer 1

嘗試

_session.QueryOver<Task>() 
    .Where(x => x.Category == category) 
    .Fetch(x => x.SubTasks).Eager 
    .List<Task>() 
    .Select(
     x => x.Id, 
     x => x.DisplayName, 
     x => x.SubTasks) 
    .ToList(); 

我發現這個通過創建一個列表，然後做後選擇工作。