LS throwing null ref exception when Sql QueryBuilder trying to resolve SingleColumnPredicate

hi, we're running on nightly build from 07 Mar.
Seeing something strange - hoping you can explain why...

We have a 1-many relationship between two soft-deleted entities. EntityB has many EntityA. Model has custom naming strategy - db has DeletedOnUtc as soft delete column. Issuing query like so:

            var query = new Query
                {
                    QueryExpression = (
                        Mindscape.LightSpeed.Entity.Attribute(EntityA.PropertyXField) == "blah" &&
                                Mindscape.LightSpeed.Entity.Attribute("EntityB.PropertyY") == "uhoh"
                            )
                };

            sut.Find<EntityA>(query);

we're seeing it blow up with a null ref exception like so:

 at Mindscape.LightSpeed.Sql.PredicateCriteria.Bind(CommandBuilder commandBuilder) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Sql\PredicateCriteria.cs:line 79
 at Mindscape.LightSpeed.Sql.CriteriaStatement.BindParameters(CommandBuilder commandBuilder) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Sql\CriteriaStatement.cs:line 25
 at Mindscape.LightSpeed.Sql.SelectStatement.BindParameters(CommandBuilder commandBuilder) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Sql\SelectStatement.cs:line 520
 at Mindscape.LightSpeed.Sql.ExistsCriteria.Bind(CommandBuilder commandBuilder) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Sql\ExistsCriteria.cs:line 24
 at Mindscape.LightSpeed.Sql.LogicalCriteria.Bind(CommandBuilder commandBuilder) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Sql\LogicalCriteria.cs:line 37
 at Mindscape.LightSpeed.Sql.LogicalCriteria.Bind(CommandBuilder commandBuilder) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Sql\LogicalCriteria.cs:line 36
 at Mindscape.LightSpeed.Sql.CriteriaStatement.BindParameters(CommandBuilder commandBuilder) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Sql\CriteriaStatement.cs:line 25
 at Mindscape.LightSpeed.Sql.SelectStatement.BindParameters(CommandBuilder commandBuilder) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Sql\SelectStatement.cs:line 520
 at Mindscape.LightSpeed.Data.CommandBuilder.AppendSql(SqlStatement sqlStatement) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Data\CommandBuilder.cs:line 110
 at Mindscape.LightSpeed.Data.CommandBuilder.AppendSql(IEnumerable`1 sqlStatements) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Data\CommandBuilder.cs:line 104
 at Mindscape.LightSpeed.Data.BatchingQueryExecutionStrategy..ctor(IUnitOfWork unitOfWork, IEnumerable`1 sqlStatements) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Data\BatchingQueryExecutionStrategy.cs:line 20
 at Mindscape.LightSpeed.Data.DataProviderAdapter.CreateQueryExecutionStrategy(IUnitOfWork unitOfWork, IEnumerable`1 sqlStatements, ProviderOptions providerOptions) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Data\DataProviderAdapter.cs:line 101
 at Mindscape.LightSpeed.Mapping.ObjectLoader.LoadInternal(TypeModel typeModel, Query query, IList results) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Mapping\ObjectLoader.cs:line 56
 at Mindscape.LightSpeed.Mapping.ObjectLoader.Load(UnitOfWorkBase unitOfWork, TypeModel typeModel, Query query, IList results) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\Mapping\ObjectLoader.cs:line 19
 at Mindscape.LightSpeed.QueryingEngine.FindInternal(Query query, TypeModel typeModel, IList results) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\QueryingEngine.cs:line 395
 at Mindscape.LightSpeed.QueryingEngine.Find(Query query, IList results) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\QueryingEngine.cs:line 135
 at Mindscape.LightSpeed.UnitOfWork.Find(Query query, IList results) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\UnitOfWork.cs:line 281
 at Mindscape.LightSpeed.UnitOfWorkBase.Find[TEntity](Query query) in D:\Libraries\Mindscape\LightSpeed\Source20120308\Src\Framework\UnitOfWorkBase.cs:line 297
 at Tests.UnitOfWorkTests.when_performing_test_that_should_pass() in Tests.UnitOfWorkTests.cs:line 273
 at Machine.Specifications.Catch.Exception(Action throwingAction)

]

Specifically, stepping into the LS code shows us that QueryBuilderBase.VisitSingleColumnPredicate is travelling all the way through the function to the bottom where the first argument provided [predicateExpression.IdentifierExpression.Accept(this)] resolves to null:

return new PredicateCriteria(
    predicateExpression.IdentifierExpression.Accept(this),
    predicateExpression.Operator.ToString(),
    toDbCriteria(predicateExpression.RhsExpressions[0].Accept(this)));

... which ends up passing a null criteria to the PredicateCriteria... which later blows up.

any obvious things we should be looking for? we were previously on a nightly build from sometime in November.

of course we're only looking at this nightly build in desperation to try and resolve some other weird inheritance-related problems we've introduced into the model. have seen many refs in the weekly notes to fixes you've made in LS wrt handling inheritance, hoping that will fix our problem A. but in the meantime we've discovered a problem B...!

thanks justin

This may mean that LightSpeed was unable to resolve predicateExpression.IdentifierExpression, for example because it does not resolve to a valid field or dotted path. (Though usually I would expect a specific error in this case rather than a null reference exception.) Take a look at predicateExpression.IdentifierExpression to see if anything is obviously fishy about it, and trace into Visit(IdentifierExpression) to figure out why it isn't returning a value.

even betterer - have attached a repro.

:)

if i rename the column in the db to DeletedOn and remove the custom naming strategy then it all passes...

Yep, there's a bug where we were internally using the column name in place of the field name while adding the 'and DeletedOn is not null' clause to the query on the EntityB association. It will be fixed in the next nightly.

huzzah - thanks very much for a super quick response.