GetDatabaseValues for owned type throws exception if the type is only used by one entity

[coder925]

Calling EntityEntry.GetDatabaseValues() on an owned type can raise an exception in certain circumstances.

Steps to reproduce

1. Run this simplified project that is only using the Order and ShipmentAddress entities:
   https://github.com/coder925/EntityFramework.Docs/tree/owned-type-issue/samples/core/Modeling/OwnedEntities

Expected result: Only the changed properties of the owned entity is saved.
Actual result: An exception:

System.InvalidOperationException
  HResult=0x80131509
  Message=Cannot create a DbSet for 'StreetAddress' because it is configured as an owned entity type and should be accessed through the defining entities.
  Source=Microsoft.EntityFrameworkCore
  StackTrace:
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.get_EntityType()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.CheckState()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.get_EntityQueryable()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.System.Linq.IQueryable.get_Provider()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.AsNoTracking[TEntity](IQueryable`1 source)
   at Microsoft.EntityFrameworkCore.Internal.EntityFinder`1.GetDatabaseValuesQuery(InternalEntityEntry entry)
   at Microsoft.EntityFrameworkCore.Internal.EntityFinder`1.GetDatabaseValues(InternalEntityEntry entry)
   at Microsoft.EntityFrameworkCore.ChangeTracking.EntityEntry.GetDatabaseValues()
   at EFModeling.OwnedEntities.Program.Main(String[] args) in C:\repos-github\EntityFramework.Docs\samples\core\Modeling\OwnedEntities\Program.cs:line 46

Workaround:
Uncomment code in OwnedEntityContext:

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            #region OwnsOne
            modelBuilder.Entity<Order>().OwnsOne(p => p.ShippingAddress);
            #endregion

            // Uncomment following line and it starts working
            #region OwnsOne
            //// modelBuilder.Entity<Order2>().OwnsOne(p => p.ShippingAddress);
            #endregion


        }

It seems if more than one Entity is owning ShipmentAddress the excpetion is not occuring.

Use case

I am receiving a detached Order entity that needs to be updated in the database. However, I am only allowed to save actual changed properties and cannot use context.Update(order) .

Instead, I use this read-update pattern:

var orderEntry = context.Attach(order);
orderEntry.OriginalValues.SetValues(orderEntry.GetDatabaseValues());

and for each owned type owned by Order (i.e. value objects):

var shippingAddressEntry = context.Entry(order.ShippingAddress);
shippingAddressEntry.OriginalValues.SetValues(shippingAddressEntry.GetDatabaseValues());

Further technical details

EF Core version: 3.0.0
Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: .NET Core 3.0
Operating system: Windows 10 Enterprise
IDE: Visual Studio 2019 16.3.0

[smitpatel]

var shippingAddressEntry = context.Entry(order.ShippingAddress);

This is invalid. We don't have a way to determine the IEntityType so it should throw. Further, given the "work-around", we are also processing owned & weak entity differently in that code path.

[coder925]

Thank you @smitpatel for pointing me in the right direction. I was confused because I got it to work sometimes depending on how the model was configured as showcased.

Do you know the right way to get database values for an owned type so I can keep track on which properties actually been changed?

[smitpatel]

Untested but try this

var shippingAddressEntry = orderEntry.Reference("ShippingAddress").TargetEntry;

[coder925]

Thanks for your suggestion!
Unfortunately, it gives the same exception when trying to fetch the database values on the next line:

var dbValues = shippingAddressEntry.GetDatabaseValues();

[AndriySvyryd]

This is related to #16186