EF Core Inheritance: Profile Field Null on Retrieval Despite of Configured Relationships

[fasoltanzadeh]

I'm encountering an issue with Entity Framework Core (EF Core) related to lazy loading, inheritance, and property retrieval. Initially, I had the following entity classes:

public class Pool
{
    public int Id { get; set; }
    public Profile? Profile
    {
        get
        {
            return ORMAProfileAccessor as Profile ?? ORMBProfileAccessor;
        }

        set
        {
            switch (value)
            {
                case AProfile aProfile:
                    ORMAProfileAccessor = aProfile;
                    break;
                case BProfile bProfile:
                    ORMBProfileAccessor = bProfile;
                    break;
                default:
                    throw new InvalidCastException("Invalid profile type");
            }
        }
    }
    internal virtual AProfile? ORMAProfileAccessor { get; set; }
    internal virtual BProfile? ORMBProfileAccessor { get; set; }
}

public abstract class Profile
{
    public Profile() { }
    public int Id { get; set; }
}

public class AProfile : Profile
{
    public AProfile() { }
    public virtual Pool? Pool { get; set; }
}

public class BProfile : Profile
{
    public BProfile() { }
    public virtual Pool? Pool { get; set; }
}

In the OnModelCreating method, I configured the relationships as follows:

modelBuilder.Entity<AProfile>().HasOne(P => P.Pool).WithOne(Q => Q.ORMAProfileAccessor).HasForeignKey<Pool>("AProfileId").IsRequired(false);
modelBuilder.Entity<BProfile>().HasOne(P => P.Pool).WithOne(Q => Q.ORMBProfileAccessor).HasForeignKey<Pool>("BProfileId").IsRequired(false);
modelBuilder.Entity<Pool>().Ignore(P => P.Profile);

The issue I'm facing now is that after saving a Pool object to the database with associated Profile, upon retrieving the Pool elsewhere in the code, the Profile field remains null. However, retrieving a Profile separately shows that the Pool field within the Profile object is correctly populated. For example:

var retrievedPool = dbContext.Pools.FirstOrDefault();
if (retrievedPool != null)
{
    Console.WriteLine($"Retrieved Pool ID: {retrievedPool.Id}");
    Console.WriteLine($"Retrieved Pool Profile ID: {retrievedPool.Profile?.Id}"); // This returns null
}

How can I ensure that when retrieving a Pool, the Profile field is populated with the associated Profile type?

Any insights or suggestions would be highly appreciated. Thank you!

EF Core version: 6.0.16 Database provider:Microsoft.EntityFrameworkCore.SqlServer Target framework: .NET 6.0 IDE: Visual Studio 2022 17.4

[ajcvickers]

@fasoltanzadeh How are you configuring lazy-loading? Does it not throw saying that "ORMAProfileAccessor" cannot be overridden?

[fasoltanzadeh]

@fasoltanzadeh How are you configuring lazy-loading? Does it not throw saying that "ORMAProfileAccessor" cannot be overridden?

@ajcvickers No It does work perfectly and it fills the database correctly, Here is the config for lazy loading:

 optionsBuilder.UseLazyLoadingProxies();

[ajcvickers]

Note for triage: underlying issue here is that internal properties are considered valid for lazy-loading, but then don't work because they cannot be overridden. Simple repro:

using (var context = new SomeDbContext())
{
    await context.Database.EnsureDeletedAsync();
    await context.Database.EnsureCreatedAsync();

    context.Add(new Pool { ORMAProfileAccessor = new AProfile() } );

    await context.SaveChangesAsync();
}

using (var context = new SomeDbContext())
{
    var pool = context.Set<Pool>().Single();
    Console.WriteLine(pool.ORMAProfileAccessor);
}

public class SomeDbContext : DbContext
{
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        => optionsBuilder
            .UseSqlServer(@"Data Source=(LocalDb)\MSSQLLocalDB;Database=AllTogetherNow")
            .UseLazyLoadingProxies()
            .LogTo(Console.WriteLine, LogLevel.Information)
            .EnableSensitiveDataLogging();

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<AProfile>().HasOne(P => P.Pool).WithOne(Q => Q.ORMAProfileAccessor).HasForeignKey<Pool>("AProfileId").IsRequired(false);
    }
}

public class Pool
{
    public int Id { get; set; }
    internal virtual AProfile ORMAProfileAccessor { get; set; }
}

public class AProfile
{
    public int Id { get; set; }
    public virtual Pool? Pool { get; set; }
}

[soroshsabz]

ITNOA

I have same issue

[meghasemim1999]

I have the same issue here.

[Reza-Noei]

@ajcvickers I'm not sure if its directly related to internal properties. I'm protecting all of my navigation properties (Collection<T> most of the time) by marking them as internal.

So I make them visible to EF using (in .csproj file):

<ItemGroup>
    <InternalsVisibleTo Include="Application.Data"/>
</ItemGroup>

I haven't seen any issue with Collections.

[soroshsabz]

@ajcvickers Did you have any time estimate to resolve this issue?

[ajcvickers]

@soroshsabz This issue is tracking making EF throw in model validation when internal navigations are used in lazy-loading proxies. The reason the navigation is null is that proxies cannot override internal methods, since they are not visible to the proxy assembly. This isn't a critical bug to fix, since the scenario is already invalid, it should just throw with a better exception message.

[soroshsabz]

@ajcvickers as you can see in @Reza-Noei comments, internal accessor does not cause of this problem, I have many project with internal accessor (and <InternalsVisibleTo Include="Assembly"/>) and works correctly too.

So I do not think the root cause of the problem from this place

[soroshsabz]

@ajcvickers I think you can probably reproduce this bug, without using any internal too.

such as below code

public class Pool
{
    public int Id { get; set; }
    public Profile? Profile
    {
        get
        {
            return ORMAProfileAccessor as Profile ?? ORMBProfileAccessor;
        }

        set
        {
            switch (value)
            {
                case AProfile aProfile:
                    ORMAProfileAccessor = aProfile;
                    break;
                case BProfile bProfile:
                    ORMBProfileAccessor = bProfile;
                    break;
                default:
                    throw new InvalidCastException("Invalid profile type");
            }
        }
    }
    public virtual AProfile? ORMAProfileAccessor { get; set; }
    public virtual BProfile? ORMBProfileAccessor { get; set; }
}

public abstract class Profile
{
    public Profile() { }
    public int Id { get; set; }
}

public class AProfile : Profile
{
    public AProfile() { }
    public virtual Pool? Pool { get; set; }
}

public class BProfile : Profile
{
    public BProfile() { }
    public virtual Pool? Pool { get; set; }
}

[soroshsabz]

related to https://github.com/dotnet/EntityFramework.Docs/issues/4486

[soroshsabz]

@ajcvickers I add some complete project for reproducing this problem, without using any internal in https://github.com/soroshsabz/TestSolution/tree/main/Source/ConsoleTest/ConsoleApp1

Please see it

thanks :)

[ajcvickers]

@soroshsabz That code doesn't use lazy-loading. When I add lazy-loading proxies, then I get:

C:\Users\avickers\AppData\Local\Programs\Rider\plugins\dpa\DotFiles\JetBrains.DPA.Runner.exe --handle=19956 --backend-pid=31380 --etw-collect-flags=3 --detach-event-name=dpa.detach.19956 C:/local/code/AllTogetherNow/Daily/bin/Debug/net8.0/Daily.exe
Hello, World!
Pool2: 1
Pool2.Profile: 2
Pool2: 1
Pool2.Profile: 2

[soroshsabz]

@ajcvickers Sorry, I mistake.

I have question, why proxy could not override internal navigation when I set <InternalsVisibleTo Include="Assembly"/>?

[ajcvickers]

Note for triage: verified that lazy-loading works with [assembly: InternalsVisibleTo("DynamicProxyGenAssembly2")]. Putting on the backlog to throw when attempting to load if the navigation exists but is not visible.