EF.Functions could not be translated and will be evaluated locally when used as key of GroupBy?

[yyjdelete]

Describe what is not working as expected.

Since #10404 is not available now, I'm trying to use DateDiffDay to get it for groupby, but found EF.Functions also not works for groupby.
EF.Functions could not be translated and will be evaluated locally when used as key of GroupBy?

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None

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dbContext.CommDataDay
                    .GroupBy(d => (EF.Functions.DateDiffDay(new DateTime(2000, 1, 2), d.StartTime) % 7 + 7) % 7)
                    .Select(d => new { Dw = (DayOfWeek)d.Key, Value = d.Sum(d1=>d1.DeltaValue) })
                    .ToList();

dbContext.CommDataDay
                    .Select(d => new { Dw = (EF.Functions.DateDiffDay(new DateTime(2000, 1, 2), d.StartTime) % 7 + 7) % 7, d.DeltaValue })
                    .GroupBy(d => d.Dw)
                    .Select(d => new { Dw = (DayOfWeek)d.Key, Value = d.Sum(d1=>d1.DeltaValue) })
                    .ToList();

Microsoft.EntityFrameworkCore.Query Warn The LINQ expression 'GroupBy((((__Functions_0.DateDiffDay(2000/1/2 0:00:00, [d].StartTime) % 7) + 7) % 7), [d])' could not be translated and will be evaluated locally.

Microsoft.EntityFrameworkCore.Database.Command Info Executed DbCommand (67ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
SELECT [d].[Start_Time], [d].[Delta_Value]
FROM [Comm_Data_Day] AS [d]
ORDER BY ((DATEDIFF(DAY, '2000-01-02T00:00:00.0000000', [d].[Start_Time]) % 7) + 7) % 7

Further technical details

EF Core version: (found in project.csproj or packages.config)2.1.2
Database Provider: (e.g. Microsoft.EntityFrameworkCore.SqlServer) Microsoft.EntityFrameworkCore.SqlServer
Operating system: Win10 x64(1803 17134)
IDE: (e.g. Visual Studio 2017 15.4)VS2017 15.8p5

[smitpatel]

Can you try wrapping up your key into an anonymous type?

[smitpatel]

Superset of #12476

[yyjdelete]

wrapping up your key into an anonymous type works for me.

[smitpatel]

Duplicate of #12476