OwnedTypes

This repository contains code to demonstrate an error I'm getting when using Proxies in EF Core 2.1.0-rc1-final

OwnedTypes project is working without any exception.

OwnedTypes.NotWorking gives the following exception when I query for data already in the database.

{System.NullReferenceException: Object reference not set to an instance of an object.
   at lambda_method(Closure , QueryContext , Person , Object[] )
   at Microsoft.EntityFrameworkCore.Query.Internal.IncludeCompiler._Include[TEntity](QueryContext queryContext, TEntity entity, Object[] included, Action`3 fixup)
   at lambda_method(Closure , TransparentIdentifier`2 )
   at System.Linq.Enumerable.SelectEnumerableIterator`2.MoveNext()
   at System.Linq.Enumerable.TryGetFirst[TSource](IEnumerable`1 source, Boolean& found)
   at lambda_method(Closure )
   at Microsoft.EntityFrameworkCore.Query.Internal.LinqOperatorProvider.ResultEnumerable`1.GetEnumerator()
   at Microsoft.EntityFrameworkCore.Query.Internal.LinqOperatorProvider.<_TrackEntities>d__17`2.MoveNext()
   at Microsoft.EntityFrameworkCore.Query.Internal.LinqOperatorProvider.ExceptionInterceptor`1.EnumeratorExceptionInterceptor.MoveNext()
   at System.Linq.Enumerable.TryGetFirst[TSource](IEnumerable`1 source, Boolean& found)
   at System.Linq.Enumerable.First[TSource](IEnumerable`1 source)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass15_1`1.<CompileQueryCore>b__0(QueryContext qc)
   at System.Linq.Queryable.FirstOrDefault[TSource](IQueryable`1 source)
   at OwnedTypes.NotWorking.Program.Main(String[] args) in ...\OwnedTypes\OwnedTypes.NotWorking\Program.cs:line 26}

What's Comman between OwnedTypes Project and OwnedTypes.NotWorking project

They both uses EF Core 2.1.0-rc1-final

They both have the following model.

FullName, FirstName and LastName are OwnedTypes (ValueObjects in DDD)

Both console applications will Create a database called OwnedTypesTestDb in your localdb, insert some data and query those inserted data.

Program.cs has the following code

class Program
{
    static void Main(string[] args)
    {
        using (TestDbContext db = new TestDbContext())
        {
            db.Database.EnsureDeleted();
            db.Database.EnsureCreated();

            db.Applicants.Add(new Applicant(new FullName(FirstName.Create("Amila"), LastName.Create("Udayanga"))));

            var person = new Person(new FullName(FirstName.Create("Amila"), LastName.Create("Udayanga")));
            person.Address = new Address { Line1 = "Line1", Line2 = "Line2" };
            db.People.Add(person);
            db.SaveChanges();
        }

        using (TestDbContext db = new TestDbContext())
        {
            var people = db.People.FirstOrDefault();
            var applicants = db.Applicants.ToList();
            var addresses = db.Addresses.ToList();
        }
    }
}

As you can see, I have two using statements. It works fine if I have the code as follows (all the code in one using statement).

class Program
{
    static void Main(string[] args)
    {
        using (TestDbContext db = new TestDbContext())
        {
            db.Database.EnsureDeleted();
            db.Database.EnsureCreated();

            db.Applicants.Add(new Applicant(new FullName(FirstName.Create("Amila"), LastName.Create("Udayanga"))));

            var person = new Person(new FullName(FirstName.Create("Amila"), LastName.Create("Udayanga")));
            person.Address = new Address { Line1 = "Line1", Line2 = "Line2" };
            db.People.Add(person);
            db.SaveChanges();

            var people = db.People.FirstOrDefault();
            var applicants = db.Applicants.ToList();
            var addresses = db.Addresses.ToList();
        }
    }
}

Difference between OwnedTypes project and OwnedTypes.NotWorking project

OwnedTypes.NotWorking is using Microsoft.EntityFrameworkCore.Proxies and the model is updated with what's required for Proxies to work (i.e. Virtual Navigation Properties, called UseLazyLoadingProxies() in DbContext configuration)