EF Core query

[RichardD2]

I have an existing .NET Framework 4.8 WebAPI project using AutoMapper v10.1.1 and EF Core 3.1, which I am upgrading to .NET 6, AutoMapper 11.0.1, and EF Core 6.0.6.

The source model contains an owned entity:

public class Settings
{
    public int Id { get; set; }
    ...
    public AdditionalSettings Additional { get; set; }
}

[Owned]
public class AdditionalSettings
{
    public bool Foo { get; set; }
    ...
}

...

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);
    modelBuilder.Entity<Settings>().OwnsOne(s => s.Additional);
}

CREATE TABLE Settings
(
    Id int IDENTITY(1, 1) NOT NULL,
    ...
    Additional_Foo bit NULL,
    ...
);

The target model flattens the data:

public class SettingsDto
{
    public int Id { get; set; }
    public bool Foo { get; set; }
}

...

configuration.CreateMap<Settings, SettingsDto>()
    .ForMember(s => s.Foo, o => o.MapFrom(s => s.Additional.Foo));

I then use ProjectTo to load a specific DTO instance:

SettingsDto result = context.Set<Settings>()
    .ProjectTo<SettingsDto>(configurationProvider)
   .First(s => s.Id == 42);

In the .NET Framework version, this works as expected. If none of the owned entity columns are set, the SettingsDto.Foo property is set to false.

In the .NET 6 version, if none of the owned entity columns are set, I get an exception:

Nullable object must have a value

To resolve the problem, I had to cast the MapFrom property to bool?, as mentioned on StackOverflow:

configuration.CreateMap<Settings, SettingsDto>()
    .ForMember(s => s.Foo, o => o.MapFrom(s => (bool?)s.Additional.Foo));

I couldn't see this change in behaviour documented anywhere. And I'm not entirely sure whether it's AutoMapper or EF Core which has caused it.

[lbargaoanu]

Check the execution plan. Compare it bettween the two versions. If it's the same, it's EF Core.

[RichardD2]

The generated queries are different. However, I suspect that's more due to improvements in EF Core.

.NET Framework + EF Core 3.1 + AutoMapper 10.1:

SELECT TOP(1) [c].[Id], ..., [t4].[Foo] AS [Foo]
FROM [dbo].[Settings] AS [c]
LEFT JOIN (
    SELECT [c5].[Id], [c5].[Foo]
    FROM [dbo].[Settings] AS [c5]
    WHERE [c5].[Foo] IS NOT NULL
) AS [t4] ON [c].[Id] = [t4].[Id]
WHERE [c].[Id] = @__id_0

.NET 6 + EF Core 6.0.6 + AutoMapper 11.0.1:

Original query:

SELECT TOP(1) [c].[Id], ..., [c].[Foo] AS [Foo]
FROM [dbo].[Settings] AS [c]
WHERE [c].[Id] = @__id_0

Fixed query:

SELECT TOP(1) [c].[Id], ... COALESCE([c].[Foo], CAST(0 AS bit)) AS [Foo]
FROM [dbo].[Settings] AS [c]
WHERE [c].[Id] = @__id_0

[jbogard]

Try checking the actual LINQ Select query between those versions with AutoMapper, you can recreate that Select query yourself too.

[RichardD2]

The LINQ expressions are the same for the .NET Framework and the unfixed .NET 6 queries. Pulling out the relevant part:

.NET Framework + EF Core 3.1 + AutoMapper 10.1:

.Select(dtoSettings => new SettingsDto() { ... Foo = dtoSettings.Additional.Foo }).Where(c => c.Id == 11)

.NET 6 + EF Core 6.0.6 + AutoMapper 11.0.1:

Original:

.Select(dtoSettings => new SettingsDto() { ... Foo = dtoSettings.Additional.Foo }).Where(c => c.Id == 11)

Fixed:

.Select(dtoSettings => new SettingsDto() { ... Foo = (Convert(dtoSettings.Additional.Foo, Nullable`1) ?? new Boolean()) }).Where(c => c.Id == 11)