LINQ query throws ArgumentOutOfRangeException

Hello,

Consider three entities, namely Workspace, Item and Document. Document inherits from Item and Workspace has a one to many relationship with Item.  Each user has a Workspace with a name "MyName".  Users may also have other Workspaces with other names.  My aim is to delete all documents in the "MyName" workspace, for which the condition on the document is true.  For example, I may look at the documents' relationship to other entities and if none exist delete them.

var workspaces = unitOfWork.Query<Workspace>().Where(w => w.Name == "MyName");

foreach (var document in workspaces.SelectMany(w => w.Items.OfType<Document>()))

{

   // remove the document if a condition is met

}

However, if there are no workspaces with the name "MyName", then the following exception is thrown in the foreach.  See below. Any ideas?

Werner

System.ArgumentOutOfRangeException occurred

  Message=Index was out of range. Must be non-negative and less than the size of the collection.

Parameter name: index

  Source=mscorlib

  ParamName=index

  StackTrace:

       at System.SZArrayHelper.get_Item[T](Int32 index)

       at Mindscape.LightSpeed.Linq.Sqo.SelectMany.DeriveBackReferencePath(Type parentType, Type childType, Expression expression, Expression projectorToIgnore)

       at Mindscape.LightSpeed.Linq.Sqo.SelectMany.DeriveBackReferencePath(Type parentType, Type childType, Expression expression, Expression projectorToIgnore)

       at Mindscape.LightSpeed.Linq.Sqo.SelectMany.DeriveBackReferencePath(Type parentType, Type childType, Expression expression, Expression projectorToIgnore)

       at Mindscape.LightSpeed.Linq.Sqo.SelectMany.EvaluateSingleArgument(ExpressionVisitor visitor, MethodCallExpression expression)

       at Mindscape.LightSpeed.Linq.Sqo.SelectMany.Evaluate(ExpressionVisitor visitor, MethodCallExpression expression)

       at Mindscape.LightSpeed.Linq.Plan.LinqQueryBuilder.VisitMethodCall(MethodCallExpression exp)

       at Mindscape.LightSpeed.Linq.Plan.LinqQueryBuilder.Visit(Expression exp)

       at Mindscape.LightSpeed.Linq.Plan.LinqQueryBuilder.Build(Expression translation, LinqQueryProvider provider)

       at Mindscape.LightSpeed.Linq.LinqQueryProvider.GetExecutionPlan(Expression expression)

       at Mindscape.LightSpeed.Linq.LinqQueryProvider.Execute(Expression expression)

       at Mindscape.LightSpeed.Linq.LinqQueryProvider.System.Linq.IQueryProvider.Execute(Expression expression)

       at Mindscape.LightSpeed.Linq.LinqQuery`1.GetEnumerator()

       at Workshare.Cloud.Jobs.DeleteOrphanDocumentsJob.Execute(JobExecutionContext context) in S:\Cloud\src\Cloud\Jobs\DeleteOrphanDocumentsJob.cs:line 45

Thanks for letting us know about this -- we will investigate.  In the meantime the following workaround works for us:

var ds = (from w in UnitOfWork.Workspaces
              where w.Name == "MyName"
              from i in w.Items
              where i.Kind == DocumentKind
              select i).Cast<Document>();

where Kind is the discriminator attribute and DocumentKind is the discriminator value for the Document class.

We'll try to get you a fix for the OfType<> version and extension method syntax in the near future.