如何在Orchard CMS中进行左连接？

Question

我有以下2个存储库：

Orchard.Data.IRepository<WeekRecord> mWeekRecords;
Orchard.Data.IRepository<StorePartRecord> mStorePartRecords;

我有以下查询

from w in mWeekRecords.Table

join s in mStorePartRecords.Table on w.StoreID equals s.StoreID into ts
from rs in ts.DefaultIfEmpty()

select new {...};

但它抛出以下异常

System.NotImplementedException: The method or operation is not implemented.
   at NHibernate.Linq.CacheableExpressionNode.Resolve(ParameterExpression inputParameter, Expression expressionToBeResolved, ClauseGenerationContext clauseGenerationContext)
   at Remotion.Linq.Parsing.Structure.IntermediateModel.ExpressionResolver.GetResolvedExpression(Expression unresolvedExpression, ParameterExpression parameterToBeResolved, ClauseGenerationContext clauseGenerationContext)
   at Remotion.Linq.Parsing.Structure.IntermediateModel.JoinExpressionNode.<>c__DisplayClass1.<GetResolvedOuterKeySelector>b__0(ExpressionResolver r)
   at Remotion.Linq.Parsing.Structure.IntermediateModel.ResolvedExpressionCache`1.GetOrCreate(Func`2 generator)
   at Remotion.Linq.Parsing.Structure.IntermediateModel.JoinExpressionNode.GetResolvedOuterKeySelector(ClauseGenerationContext clauseGenerationContext)
   at Remotion.Linq.Parsing.Structure.IntermediateModel.JoinExpressionNode.CreateJoinClause(ClauseGenerationContext clauseGenerationContext)
   at Remotion.Linq.Parsing.Structure.IntermediateModel.GroupJoinExpressionNode.ApplyNodeSpecificSemantics(QueryModel queryModel, ClauseGenerationContext clauseGenerationContext)
   at Remotion.Linq.Parsing.Structure.IntermediateModel.MethodCallExpressionNodeBase.Apply(QueryModel queryModel, ClauseGenerationContext clauseGenerationContext)
   at Remotion.Linq.Parsing.Structure.QueryParser.ApplyAllNodes(IExpressionNode node, ClauseGenerationContext clauseGenerationContext)
   at Remotion.Linq.Parsing.Structure.QueryParser.ApplyAllNodes(IExpressionNode node, ClauseGenerationContext clauseGenerationContext)
   at Remotion.Linq.Parsing.Structure.QueryParser.ApplyAllNodes(IExpressionNode node, ClauseGenerationContext clauseGenerationContext)
   at Remotion.Linq.Parsing.Structure.QueryParser.ApplyAllNodes(IExpressionNode node, ClauseGenerationContext clauseGenerationContext)
   at Remotion.Linq.Parsing.Structure.QueryParser.ApplyAllNodes(IExpressionNode node, ClauseGenerationContext clauseGenerationContext)
   at Remotion.Linq.Parsing.Structure.QueryParser.GetParsedQuery(Expression expressionTreeRoot)
   at NHibernate.Linq.NhRelinqQueryParser.Parse(Expression expression)
   at NHibernate.Linq.NhLinqExpression.Translate(ISessionFactoryImplementor sessionFactory, Boolean filter)
   at NHibernate.Hql.Ast.ANTLR.ASTQueryTranslatorFactory.CreateQueryTranslators(IQueryExpression queryExpression, String collectionRole, Boolean shallow, IDictionary`2 filters, ISessionFactoryImplementor factory)
   at NHibernate.Engine.Query.QueryExpressionPlan.CreateTranslators(IQueryExpression queryExpression, String collectionRole, Boolean shallow, IDictionary`2 enabledFilters, ISessionFactoryImplementor factory)
   at NHibernate.Engine.Query.QueryExpressionPlan..ctor(IQueryExpression queryExpression, Boolean shallow, IDictionary`2 enabledFilters, ISessionFactoryImplementor factory)
   at NHibernate.Engine.Query.QueryPlanCache.GetHQLQueryPlan(IQueryExpression queryExpression, Boolean shallow, IDictionary`2 enabledFilters)
   at NHibernate.Impl.AbstractSessionImpl.GetHQLQueryPlan(IQueryExpression queryExpression, Boolean shallow)
   at NHibernate.Impl.AbstractSessionImpl.CreateQuery(IQueryExpression queryExpression)
   at NHibernate.Linq.DefaultQueryProvider.PrepareQuery(Expression expression, IQuery& query, NhLinqExpression& nhQuery)
   at NHibernate.Linq.DefaultQueryProvider.Execute(Expression expression)
   at NHibernate.Linq.DefaultQueryProvider.Execute[TResult](Expression expression)
   at System.Linq.Queryable.Count[TSource](IQueryable`1 source)
   at MyCompany.UI.Common.TableHelper`13.QueryAndCreateRows(HttpSessionStateBase aSessionObject, Int32& aPageNumber, Nullable`1 aPageSize, Dictionary`2 aSorting, TFilterSetup aFilterSetup, IEnumerable`1 aColumns)
   at MyCompany.UI.Common.TableHelper`13.GetRows(HttpSessionStateBase aSessionObject, IEnumerable`1 aColumns)
   at MyCompany.LunchMenu.Controllers.HomeController.Index()
   at lambda_method(Closure , ControllerBase , Object[] )
   at System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters)
   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.Async.AsyncControllerActionInvoker.ActionInvocation.InvokeSynchronousActionMethod()
   at System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult)
   at System.Web.Mvc.Async.AsyncResultWrapper.WrappedAsyncResultBase`1.End()
   at System.Web.Mvc.Async.AsyncResultWrapper.End[TResult](IAsyncResult asyncResult, Object tag)
   at System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult)
   at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d()
   at System.Web.Mvc.Async.AsyncControllerActionInvoker.AsyncInvocationWithFilters.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f()

我还读过LINQ to NHibernate does not support左连接（在LINQ中由group joins建模）。

现在我想知道我如何用左连接执行查询？