.groupBy() Throw an error when used with 2 level of .FirstOrDefault()

[plaramee1]

EF core Throw an error when I use .FirstOrDefault() in a groupBy.

in the example below the code works:

 var OriginForms = db.OriginForms
   .OrderByDescending(a => a.Id)
   .Select(a => new
   {
     a.Id,
     a.Name,
     FieldCount = a.OriginFormDatas
       .GroupBy(x => x.Revision)
       .OrderByDescending(x => x.Key)
       .FirstOrDefault()
       .Select(x => x.OriginFormFieldPositions.Count())
   }).ToList();

 OriginForms.ForEach(of =>
 {
   Console.WriteLine($"ID:{of.Id},FC:{of.FieldCount.FirstOrDefault()}");
 });

This code will throw

 var OriginForms = db.OriginForms
   .OrderByDescending(a => a.Id)
   .Select(a => new
   {
     a.Id,
     a.Name,
     FieldCount = a.OriginFormDatas
       .GroupBy(x => x.Revision)
       .OrderByDescending(x => x.Key)
       .FirstOrDefault()
       .Select(x => x.OriginFormFieldPositions.Count()).DefaultIfEmpty(0).FirstOrDefault()
   }).ToList();

 OriginForms.ForEach(of =>
 {
   Console.WriteLine($"ID:{of.Id},FC:{of.FieldCount}");
 });

Exception message:
Unhandled Exception: System.ArgumentException: Value does not fall within the expected range.
   at System.SharedTypeExtensions.GetSequenceType(Type type)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.VisitMainFromClause(MainFromClause fromClause, QueryModel queryModel)
   at Remotion.Linq.QueryModelVisitorBase.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.RelationalQueryModelVisitor.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.SqlTranslatingExpressionVisitor.VisitSubQuery(SubQueryExpression expression)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.SqlTranslatingExpressionVisitor.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.SqlTranslatingExpressionVisitor.VisitUnary(UnaryExpression expression)
   at System.Linq.Expressions.UnaryExpression.Accept(ExpressionVisitor visitor)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.SqlTranslatingExpressionVisitor.VisitBinary(BinaryExpression expression)
   at Microsoft.EntityFrameworkCore.SqlServer.Query.ExpressionVisitors.Internal.SqlServerSqlTranslatingExpressionVisitor.VisitBinary(BinaryExpression binaryExpression)
   at System.Linq.Expressions.BinaryExpression.Accept(ExpressionVisitor visitor)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.SqlTranslatingExpressionVisitor.Visit(Expression expression)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.RelationalProjectionExpressionVisitor.Visit(Expression expression)
   at System.Linq.Expressions.ExpressionVisitor.VisitAndConvert[T](ReadOnlyCollection`1 nodes, String callerName)
   at Remotion.Linq.Parsing.RelinqExpressionVisitor.VisitNew(NewExpression expression)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.RelationalProjectionExpressionVisitor.VisitNew(NewExpression newExpression)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.VisitSelectClause(SelectClause selectClause, QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.RelationalQueryModelVisitor.VisitSelectClause(SelectClause selectClause, QueryModel queryModel)
   at Remotion.Linq.QueryModelVisitorBase.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.RelationalQueryModelVisitor.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.CreateQueryExecutor[TResult](QueryModel queryModel)
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](Expression query, IQueryModelGenerator queryModelGenerator, IDatabase database, IDiagnosticsLogger`1 logger, Type contextType)
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func`1 compiler)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
   at Remotion.Linq.QueryableBase`1.GetEnumerator()
   at System.Collections.Generic.List`1.AddEnumerable(IEnumerable`1 enumerable)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)

Further technical details

EF Core version: 2.2.0
Database Provider: Microsoft.EntityFrameworkCore.SqlServer
Operating system: MacOS 10.14.2
IDE: VisualStudio Code 1.30.0

[smitpatel]

Duplicate of #12089

[plaramee1]

well I just found that we can call .ToArray() and take the first index and that work....

.Select(x => x.OriginFormFieldPositions.Count()).Take(1).ToArray()[0]

Ill leave a comment in my code to fix this when 3.0 is release !