Get an EntityEntry<TEntity> for Shared Entity Types

[zoriya]

Get an EntityEntry for Shared Entity Types

Right now, it is impossible to access an EntityEntry (via Context.Entry(obj)) for a SharedEntity and this prevents us from changing states of entries.

(Not really necessary to understand the issue, but I need to access the EntityEntry of the shared entity because I want to set the state of the shared entity to Added while keeping related entities to Unchanged)

Reproducible example

private class TestEntity
{
	public int ID { get; set; }
	public ICollection<TestShared> Shared { get; set; }
}

private class TestShared
{
	public int ID { get; set; }
	public string Property { get; set; }
}

private class SharedEntityContext : DbContext
{
	public DbSet<TestEntity> Entities { get; set; }

	protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
	{
		optionsBuilder.UseSqlite(":memory:");
	}

	protected override void OnModelCreating(ModelBuilder modelBuilder)
	{
		modelBuilder.SharedTypeEntity<TestShared>("EntityShared")
			.HasKey(x => x.ID);
		modelBuilder.SharedTypeEntity<TestShared>("EntityShared")
			.HasOne<TestEntity>()
			.WithMany(x => x.Shared)
			.OnDelete(DeleteBehavior.Cascade);
	}
}

[Fact]
public void SharedEntityEntryTest()
{
	using SharedEntityContext context = new();
	
	TestEntity show = new();
	context.Entry(show); // This does not throw;

	TestShared id = new();
	context.Entry(id); // This throws.
}

Stack Traces

System.InvalidOperationException
The entity type 'TestShared' was not found. Ensure that the entity type has been added to the model.
   at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.GetOrCreateEntry(Object entity)
   at Microsoft.EntityFrameworkCore.DbContext.EntryWithoutDetectChanges[TEntity](TEntity entity)
   at Microsoft.EntityFrameworkCore.DbContext.Entry[TEntity](TEntity entity)
   at Kyoo.Tests.Database.GlobalTests.SharedEntityEntryTest() in /home/anonymus-raccoon/Projects/Kyoo/Kyoo/Kyoo.Tests/Database/SpecificTests/SanityTests.cs:line 82

Include provider and version information

EF Core version: 5.0.8
Database provider: Microsoft.EntityFrameworkCore.Sqlite 5.0.8 & Npgsql.EntityFrameworkCore.PostgreSQL 5.0.7
Target framework: NET 5.0
Operating system: Linux
IDE: Rider

[AndriySvyryd]

Try context.Set<TestShared>("EntityShared").Attach(id)

[ajcvickers]

Note for triage: Attach will always track the entity instance. We should consider an overload of "Entry" that takes the shared type name. This would return an EntityEntry without necessarily tracking it, such that things like shadow PKs can be set before starting to track.

[ajcvickers]

Consider an Entry method on DbSet.