NullReferenceException when querying projection

[Ivan Montilla]

Hello:

I have this query:

var defaultCountry = await _dSession.Query<Country>()

    .Select(x => new CountryModel(x.Code, x.Name, x.Region))

    .FirstOrDefaultAsync(cancellationToken);

With this query, I get NullReferenceException, but if I remove the Select() call, the query run.

This is the stacktrace:

System.NullReferenceException: Object reference not set to an instance of an object.

   at Raven.Client.Documents.Linq.RavenQueryProviderProcessor`1.VisitSelect(Expression operand) in C:\Builds\RavenDB-Stable-4.2\42021\src\Raven.Client\Documents\Linq\RavenQueryProviderProcessor.cs:line 2156

   at Raven.Client.Documents.Linq.RavenQueryProviderProcessor`1.VisitQueryableMethodCall(MethodCallExpression expression) in C:\Builds\RavenDB-Stable-4.2\42021\src\Raven.Client\Documents\Linq\RavenQueryProviderProcessor.cs:line 1585

   at Raven.Client.Documents.Linq.RavenQueryProviderProcessor`1.VisitMethodCall(MethodCallExpression expression, Boolean negated) in C:\Builds\RavenDB-Stable-4.2\42021\src\Raven.Client\Documents\Linq\RavenQueryProviderProcessor.cs:line 1013

   at Raven.Client.Documents.Linq.RavenQueryProviderProcessor`1.VisitExpression(Expression expression) in C:\Builds\RavenDB-Stable-4.2\42021\src\Raven.Client\Documents\Linq\RavenQueryProviderProcessor.cs:line 197

   at Raven.Client.Documents.Linq.RavenQueryProviderProcessor`1.GetAsyncDocumentQueryFor(Expression expression, Action`1 customization) in C:\Builds\RavenDB-Stable-4.2\42021\src\Raven.Client\Documents\Linq\RavenQueryProviderProcessor.cs:line 3217

   at Raven.Client.Documents.Linq.RavenQueryProvider`1.ToAsyncDocumentQuery[TResult](Expression expression) in C:\Builds\RavenDB-Stable-4.2\42021\src\Raven.Client\Documents\Linq\RavenQueryProvider.cs:line 254

   at Raven.Client.Documents.LinqExtensions.FirstOrDefaultAsync[TSource](IQueryable`1 source, CancellationToken token) in C:\Builds\RavenDB-Stable-4.2\42021\src\Raven.Client\Documents\LinqExtensions.cs:line 611

I tried to follow the execution with the debugger and I this if block:

if (newExpression.Arguments[index] is MemberExpression member && HasComputation(member) == false)

{

    AddToFieldsToFetch(GetSelectPathOrConstantValue(member), GetSelectPath(newExpression.Members[index]));

    continue;

}

https://github.com/ravendb/ravendb/blob/a1775781322e808fd15230f296733b3d9c809ad4/src/Raven.Client/Documents/Linq/RavenQueryProviderProcessor.cs#L2173

In my debugger, newExpression.Arguments[index] is null, so isn't a MemberExpression, but is entering in the if (WTF?) and when GetSelectPath(newExpression.Members[index]) is called with a null parameter, I get a NullPointerException.

Any idea?

[Oren Eini (Ayende Rahien)]

Can you create a test for this?

We need to see the whole thing

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Oren Eini CEO   /   Hibernating Rhinos LTD Mobile:  +972-52-548-6969 Sales:  sa...@ravendb.net Skype:  ayenderahien Support:  sup...@ravendb.net

[Grisha Kotler]

var defaultCountry = await _dSession.Query<Country>()

    .Select(x => new CountryModel {

         Code = x.Code,

         Name = x.Name,

         Region = x.Region

    })

    .FirstOrDefaultAsync(cancellationToken);

You can track the status of this issue here:

https://issues.hibernatingrhinos.com/issue/RavenDB-14245  

Grisha Kotler Team Leader  /   Hibernating Rhinos LTD Mobile:  +972-54-586-8647 Sales:  sa...@ravendb.net Skype:  grisha.kotler Support:  sup...@ravendb.net

To view this discussion on the web visit https://groups.google.com/d/msgid/ravendb/CAF0G-ZhV8owVzU55AaFJRRg2eQXsP1FNVy5RkrT_JU-azSJ1UA%40mail.gmail.com.

[Ivan Montilla]

Thanks Grisha, I solved it doing these, using the setters instead the constructor.

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Oren Eini CEO   /   Hibernating Rhinos LTD Mobile:  +972-52-548-6969 Sales:  sa...@ravendb.net Skype:  ayenderahien Support:  sup...@ravendb.net

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