Null checking in anonymous projection

[peterjanto]

Exception message: System.InvalidOperationException: 'No mapping to a relational type can be found for the CLR type 'Expression[]'.'
Stack trace:
   at Microsoft.EntityFrameworkCore.Storage.RelationalTypeMappingSourceExtensions.GetMapping(IRelationalTypeMappingSource typeMappingSource, Type clrType)
   at Microsoft.EntityFrameworkCore.Query.Sql.DefaultQuerySqlGenerator.GenerateSqlLiteral(Object value)
   at Microsoft.EntityFrameworkCore.Query.Sql.DefaultQuerySqlGenerator.VisitConstant(ConstantExpression constantExpression)
   at System.Linq.Expressions.ConstantExpression.Accept(ExpressionVisitor visitor)
   at Microsoft.EntityFrameworkCore.Query.Sql.DefaultQuerySqlGenerator.VisitAlias(AliasExpression aliasExpression)
   at Microsoft.EntityFrameworkCore.SqlServer.Query.Sql.Internal.SqlServerQuerySqlGenerator.GenerateProjection(Expression projection)
   at Microsoft.EntityFrameworkCore.Query.Sql.DefaultQuerySqlGenerator.GenerateList[T](IReadOnlyList`1 items, Action`1 generationAction, Action`1 joinAction)
   at Microsoft.EntityFrameworkCore.Query.Sql.DefaultQuerySqlGenerator.VisitSelect(SelectExpression selectExpression)
   at Microsoft.EntityFrameworkCore.Query.Sql.DefaultQuerySqlGenerator.GenerateSql(IReadOnlyDictionary`2 parameterValues)
   at Microsoft.EntityFrameworkCore.Query.Internal.ShaperCommandContext.GetRelationalCommand(IReadOnlyDictionary`2 parameters)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.BufferlessMoveNext(DbContext _, Boolean buffer)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.MoveNext()
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryBuffer.CorrelateSubquery[TInner,TOut,TCollection](Int32 correlatedCollectionId, INavigation navigation, Func`2 resultCollectionFactory, MaterializedAnonymousObject& outerKey, Boolean tracking, Func`1 correlatedCollectionFactory, Func`3 correlationPredicate)
   at lambda_method(Closure , QueryContext , ValueBuffer )
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.Internal.ProjectionShaper.TypedProjectionShaper`3.Shape(QueryContext queryContext, ValueBuffer& valueBuffer)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.BufferlessMoveNext(DbContext _, Boolean buffer)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.Execute[TState,TResult](TState state, Func`3 operation, Func`3 verifySucceeded)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.Enumerator.MoveNext()
   at Microsoft.EntityFrameworkCore.Query.Internal.LinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExceptionInterceptor.MoveNext()
   at System.Collections.Generic.List`1.AddEnumerable(IEnumerable`1 enumerable)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at xxxx

Steps to reproduce

public class Partner
{
   public ICollection<Address> Addresses { get; set; }
}

public class Address
{
  public AddressTurnovers Turnovers { get; set; }
}

public class AddressTurnovers
{
   public decimal AmountIn { get; set; }
}

var partners = apiContext.Partners
                .Select(x => new
                {
                    Addresses = x.Addresses.Select(y => new
                    {
                        Turnovers = y.Turnovers == null ? null : new
                        {
                            y.Turnovers.AmountIn
                        },
                    }).ToList()
                }).ToList();

Further technical details

EF Core version: 2.1.1
Database Provider: Microsoft.EntityFrameworkCore.SqlServer 2.1.1
Operating system: WIN10
IDE: Visual Studio 2017 15.7.1

[smitpatel]

@peterjanto - Thanks for the repro.

[ajcvickers]

@smitpatel This issue is approved for patch and the release\2.1 branch is now open for merging. Please ensure:

• The appropriate changes get into both the release and dev branches
• Quirking is included for the release branch only