Query: groupby doesn't get translated if the result is projected into DTO

[maumar]

This translates correctly:

                var query = ctx.Children
                    .Select(c => c.Group)
                    .GroupBy(g => g)
                    .Select(g => new
                    {
                        Group = g.Key,
                        GroupCount = g.Count()
                    }).ToList();

into:

SELECT [c].[Group], COUNT(*)
            FROM [Children] AS [c]
            GROUP BY [c].[Group]

but this:

                var query = ctx.Children
                    .Select(c => c.Group)
                    .GroupBy(g => g)
                    .Select(g => new BarVm
                    {
                        Group = g.Key,
                        GroupCount = g.Count()
                    }).ToList();

produces the following query plan:

(QueryContext queryContext) => IEnumerable<BarVm> _InterceptExceptions(
    source: IEnumerable<BarVm> _Select(
        source: IEnumerable<IGrouping<int, int>> _GroupBy(
            source: IEnumerable<ValueBuffer> _ShapedQuery(
                queryContext: queryContext, 
                shaperCommandContext: SelectExpression: 
                    SELECT [c].[Group]
                    FROM [Children] AS [c]
                    ORDER BY [c].[Group], 
                shaper: ValueBufferShaper), 
            keySelector: (ValueBuffer c) => int TryReadValue(c, 0, Child.Group), 
            elementSelector: (ValueBuffer c) => int TryReadValue(c, 0, Child.Group)), 
        selector: (IGrouping<int, int> g) => new BarVm{ 
            Group = g.Key, 
            GroupCount = int Count(g) 
        }
    ), 
    contextType: Repro10472.MyContext, 
    logger: DiagnosticsLogger<Query>, 
    queryContext: queryContext)