Misinterpreted expression with owned entities

[verdie-g]

I have one entity (Owner) containing two owned entities (Owned1 and Owned2). When selecting a row and projecting it using AutoMapper I expected both owned entities to be different than null but one of them always gets null. If I remove one owned entity the other becomes different than null. Also, if I replace the navigation property of Owned2 and replace it with an int, both entities aren't null anymore.

I've reported the issue to AutoMapper but apparently the issue would be on EF's side.

Feel free to rename the title as I haven't understand the issue.

Steps to reproduce

class Program
{
    static async Task Main()
    {
        await using var db = new MyDbContext();

        db.Owners.Add(new Owner
        {
            Owned1 = new Owned1(),
            O = new Owned2(),
        });
        await db.SaveChangesAsync();

        var config = new MapperConfiguration(cfg =>
        {
            cfg.CreateMap<Owner, OwnerViewModel>();
            cfg.CreateMap<Other, OtherViewModel>();
            cfg.CreateMap<Owned1, Owned1ViewModel>();
            cfg.CreateMap<Owned2, Owned2ViewModel>();
        });

        var c = await db.Owners
            .ProjectTo<OwnerViewModel>(config)
            .ToListAsync();

        // c.O == null
    }
}


public class Owned1ViewModel { public int A { get; set; } }
public class Owned2ViewModel { public OtherViewModel Other { get; set; } }
public class OtherViewModel { public int Id { get; set; } }

public class OwnerViewModel
{
    public int Id { get; set; }
    public Owned1ViewModel Owned1 { get; set; }
    public Owned2ViewModel O { get; set; }
}

class MyDbContext : DbContext
{
    public DbSet<Owner> Owners { get; set; }
    protected override void OnConfiguring(DbContextOptionsBuilder options) =>
        options.UseInMemoryDatabase("test");
}

public class Owner
{
    public int Id { get; set; }
    public Owned1 Owned1 { get; set; }
    public Owned2 O { get; set; }
}

[Owned] public class Owned1 { public int A { get; set; } }
[Owned] public class Owned2 { public Other Other { get; set; } }
public class Other { public int Id { get; set; } }

Further technical details

EF Core version: 3.1.3
Database provider: Microsoft.EntityFrameworkCore.InMemory
Target framework: .NET Core 3.1
Operating system: 5.6.3-arch1-1 x86_64 GNU/Linux
IDE: Rider 2020.1

[ajcvickers]

@verdie-g This is working for me with EF Core 5.0 preview 3. Can you try again with preview 3 and check that it resolves your issue?

Note for team: this was not an in-memory issue; it also reproed on SQL Server.

[verdie-g]

The issue is still present on my side using Microsoft.EntityFrameworkCore 5.0.0-preview.3.20181.2 and Microsoft.EntityFrameworkCore.InMemory 5.0.0-preview.3.20181.2. Making my project target netcoreapp5.0 didn't help.

[ajcvickers]

@verdie-g Can you extract the IQueryable into a variable:

var queryable = db.Owners.ProjectTo<OwnerViewModel>(config);
        
var c = await queryable.ToListAsync();

And then drill down into it in the debugger, expand the DebugView, and post here both the Expression and Query.

On my machine I see this:

DbSet<Owner>()
    .Select(dtoOwner => new OwnerViewModel{ 
        Id = dtoOwner.Id, 
        O = dtoOwner.O == null ? null : new Owned2ViewModel{ Other = dtoOwner.O.Other == null ? null : new OtherViewModel{ Id = dtoOwner.O.Other.Id }
             }
        , 
        Owned1 = dtoOwner.Owned1 == null ? null : new Owned1ViewModel{ A = dtoOwner.Owned1.A }
         
    }
    )

SELECT [o].[Id], CAST(0 AS bit), CASE
    WHEN [o0].[Id] IS NULL THEN CAST(1 AS bit)
    ELSE CAST(0 AS bit)
END, [o0].[Id], [o].[Owned1_A]
FROM [Owners] AS [o]
LEFT JOIN [Other] AS [o0] ON [o].[O_OtherId] = [o0].[Id]

[verdie-g]

Looks pretty similar

DbSet<Owner>()
    .Select(dtoOwner => new OwnerViewModel{ 
        Id = dtoOwner.Id, 
        O = dtoOwner.O == null ? null : new Owned2ViewModel{ Other = dtoOwner.O.Other == null ? null : new OtherViewModel{ Id = dtoOwner.O.Other.Id }
             }
        , 
        Owned1 = dtoOwner.Owned1 == null ? null : new Owned1ViewModel{ A = dtoOwner.Owned1.A }
         
    }
    )

And no query for InMemory provider.

[ajcvickers]

@verdie-g Thanks--it was my error. I didn't check again with the in-memory provider. I can now repro this on the latest daily build.