Queryable projection faults when assigning default values

[sommmen]

EF Core version: 6.0.3
Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: (e.g. .NET 5.0) .NET 6.0.3
Operating system: Windows
IDE: (e.g. Visual Studio 2019 16.3) Vs2022 17.1.1

Hello,

I have this (rather simple) entity:

public class HarvestLLTimeSheet
{

    public Guid Id { get; set; }

    public DateTimeOffset Day { get; set; }

    public double Hours { get; set; }

    [StringLength(64)]
    public string? Task { get; set; }

    [StringLength(256)]
    public string? Note { get; set; }

    [StringLength(32)]
    public string? User { get; set; }
}

I'm running some .Where() filters, then a group by and then a projection for the groupby. Here's some sample code to demonstarate:

var qTestSelectOnly = qHarvestLLTimeSheets
    .Where(c => c.Day <= DateTimeOffset.Now && c.Day >= DateTimeOffset.Now.AddMonths(-1))
    .Select(x => new HarvestLLTimeSheet
    {
        //Id = default,
        //Day = default,
        Hours = x.Hours,
        Note = x.Note,
        Task = x.Task,
        User = x.User
    });

var qTestGroupBy = qHarvestLLTimeSheets
    .Where(c => c.Day <= DateTimeOffset.Now && c.Day >= DateTimeOffset.Now.AddMonths(-1))
    .GroupBy(c => c.User)
    .Select(c => new HarvestLLTimeSheet
    {
        Hours = c.Sum(x => x.Hours),
        Note = c.Max(x => x.Note),
        Task = c.Max(x => x.Task),
        User = c.Max(x => x.User)
    });

var qTestGroupByWithDefault = qHarvestLLTimeSheets
    .Where(c => c.Day <= DateTimeOffset.Now && c.Day >= DateTimeOffset.Now.AddMonths(-1))
    .GroupBy(c => c.User)
    .Select(c => new HarvestLLTimeSheet
    {
        Id = default,
        Day = default,
        Hours = c.Sum(x => x.Hours),
        Note = c.Max(x => x.Note),
        Task = c.Max(x => x.Task),
        User = c.Max(x => x.User)
    });

var selectOnly = qTestSelectOnly.ToList();
var groupBy = qTestGroupBy.ToList();
var groupByWithDefault = qTestGroupByWithDefault.ToList();

selectOnly and groupBy works groupByWithDefault does not:

System.InvalidOperationException
  HResult=0x80131509
  Message=An error occurred while reading a database value. The expected type was 'System.Nullable`1[System.Guid]' but the actual value was of type 'System.String'.
  Source=Microsoft.EntityFrameworkCore.Relational
  StackTrace:
   at Microsoft.EntityFrameworkCore.Query.RelationalShapedQueryCompilingExpressionVisitor.ShaperProcessingExpressionVisitor.ThrowReadValueException[TValue](Exception exception, Object value, Type expectedType, IPropertyBase property)
   at Microsoft.EntityFrameworkCore.Query.Internal.SingleQueryingEnumerable`1.Enumerator.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at [REDACTED].WebApi.Controllers.HarvestLLTimeSheetController.<Get>d__2.MoveNext() in [REDACTED]\HarvestLLTimeSheetController.cs:line 96

  This exception was originally thrown at this call stack:
    Microsoft.Data.SqlClient.SqlBuffer.Guid.get()
    Microsoft.Data.SqlClient.SqlDataReader.GetGuid(int)

Inner Exception 1:
InvalidCastException: Unable to cast object of type 'System.String' to type 'System.Guid'.

The same error happens here:

var qTestSelectOnlyWithDefault = qHarvestLLTimeSheets
    .Select(x => new HarvestLLTimeSheet
    {
        Id = default,
        Day = default,
        Hours =  x.Hours,
        Note =  x.Note,
        Task =  x.Task,
        User =  x.User
    });

var selectOnlyWithDefault = qTestSelectOnlyWithDefault.ToList();

And here:

var qTestSelectOnlyWithDefault = qHarvestLLTimeSheets
    //.Where(c => c.Day <= DateTimeOffset.Now && c.Day >= DateTimeOffset.Now.AddMonths(-1))
    .Select(x => new HarvestLLTimeSheet
    {
        //Id = default,
        Day = default,
        Hours =  x.Hours,
        Note =  x.Note,
        Task =  x.Task,
        User =  x.User
    });

var selectOnlyWithDefault = qTestSelectOnlyWithDefault.ToList();

Is this intentional because this seems like a bug - hence this report.

Why i'm using default here? Well for both clarity and intellisense.

[smitpatel]

Duplicate of #24075

Issue is that the literal representation of default of Guid in SqlServer gets sent back as string so when we try to read Guid it throws above exception.

[sommmen]

Duplicate of #24075

Issue is that the literal representation of default of Guid in SqlServer gets sent back as string so when we try to read Guid it throws above exception.

I see - sorry for the dupe!