Trying to access another table through partial class property within LINQ query.

Hi!

I am not expecting this to ever work because I know I am really expecting magic to happen from Lightspeed (which often does happen so my expectations are lifted to unrealistic levels ;-))

However not sure if the exception I get is o.k.

To get this working I can setup a join.

Query:

            var blah = (from ib in Repository.FindAll<InventoryBatch>()
                        where ib.CurrentQuantity > 0
                        select ib).ToList();

The partial class:

partial class InventoryBatch
{
    public int CurrentQuantity
    {
        get
        {
            return Quantity - DispatchBatches.Sum(dpb => dpb.Quantity);
        }
    }
}

Exception:

at ..(IdentifierExpression , FieldModel& , ToOneModel& , & , String& ) at ..€(IdentifierExpression , FieldModel& , ToOneModel& , & , String& ) at ..€(IdentifierExpression ) at Mindscape.LightSpeed.Querying.IdentifierExpression.€T at ..(PredicateExpression ) at ..€(PredicateExpression ) at Mindscape.LightSpeed.Querying.PredicateExpression.€T at ..€(AliasedTypeModel , QueryExpression , Order , Group , String , Boolean , Boolean ) at ..€(LightSpeedContext , List1 , QueryExpression , Order , Group , String , Boolean , Boolean ) at ..€(List1 , Query , String , IdentifierExpression ) at ..€(AliasedTypeModel , Query , String , IdentifierExpression ) at ..€(AliasedTypeModel , Query ) at ..€(TypeModel , Query , IList ) at ..€(UnitOfWorkBase , TypeModel , Query , IList ) at ..€(Query , TypeModel , IList ) at ..€(Query , IList ) at Mindscape.LightSpeed.UnitOfWork.Find(Query query, IList results) at Mindscape.LightSpeed.UnitOfWorkBase.Find(Query query) at Mindscape.LightSpeed.Linq.Plan.SingleQueryPlan.ExecuteImmediate(IUnitOfWork unitOfWork, Type returnType) at Mindscape.LightSpeed.Linq.LinqQueryProvider.Execute(Expression expression) at Mindscape.LightSpeed.Linq.LinqQueryProvider.System.Linq.IQueryProvider.Execute(Expression expression) at Mindscape.LightSpeed.Linq.LinqQuery1.GetEnumerator() at System.Collections.Generic.List1..ctor(IEnumerable1 collection) at System.Linq.Enumerable.ToList[TSource](IEnumerable1 source)

I see that most of the stacktrace is destroyed due to the obfuscation characters.

Here a screenshot:

This happens because CurrentQuantity is a property calculated in .NET, not a column in the database. We can't decompile the CurrentQuantity getter and translate it to SQL. You need to spell it out in the query, or use a ninja domain property to express CurrentQuantity as an expression (because we can translate expressions into SQL).

Note however that not all expressions are translatable into SQL -- I'm not sure whether we would handle the CurrentQuantity expression.

Hey Ivan,

I've been looking into it, I think it is hard to translate it to SQL (as I said, I don't expect this to work), I was mostly wondering about if the exception wasn't happening 'too high up', since it was very uninformative.

Thanks nonetheless!

Good point -- we should indeed do better to identify this and provide a meaningful explanation. Thanks for the feedback!