ForeignKeyAttribute can't be overriden with explicit configuration

[xrkolovos]

my model (Steps to reproduce)

I have a model with an optional one-to-one relationship like this

public class Decision : RelativeEntity{
        public int? SessionSubjectId { get; set; }

        [ForeignKey("SessionSubjectId")]
        public virtual SessionSubject SessionSubject { get; set; }
}

public class SessionSubject : RelativeEntity {
        public int? DecisionId { get; set; }

        [ForeignKey("DecisionId")]
        public virtual Decision Decision { get; set; }
}

protected override void OnModelCreating(ModelBuilder modelBuilder) {
    modelBuilder.Entity<Decision>()
               .HasOne(ss => ss.SessionSubject)
               .WithOne(s => s.Decision)
               .HasForeignKey<SessionSubject>(m => m.DecisionId)
               .IsRequired(false);
    modelBuilder.Entity<SessionSubject>()
               .HasOne(ss => ss.Decision)
               .WithOne(s => s.SessionSubject)
               .HasForeignKey<Decision>(m => m.SessionSubjectId)
               .IsRequired(false);
}

The issue

So when the EF gets initialized and the OnModelCreating method runs, I get this error

An unhandled exception occurred while processing the request.
ArgumentNullException: Value cannot be null.
Parameter name: builder

Microsoft.EntityFrameworkCore.Utilities.Check.NotNull[T](T value, String parameterName)

If i comment the fluent api code, and then try to include one model from the other like this

Context.SessionSubjects.Include(x => x.Decision).FirstOrDefault();

I get this error

An unhandled exception occurred while processing the request.
InvalidCastException: Unable to cast object of type 'System.Linq.Expressions.Expression`1[System.Func`2[Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor+TransparentIdentifier`2[Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor+TransparentIdentifier`2[Decisions.Core.Model.Db.SessionSubject,System.Collections.Generic.IAsyncEnumerable`1[Decisions.Core.Model.Db.Decision]],Decisions.Core.Model.Db.Decision],System.Int32]]' to type 'System.Linq.Expressions.ConstantExpression'.

Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.Internal.QueryFlattener.Flatten(MethodCallExpression methodCallExpression)

Further technical details

EF Core version: 1.0.0-rc2-final
Operating system: win10
Visual Studio version: 2015

[smitpatel]

The error for model building part,
based on the exception message, seems dupe of #5657
Can you post whole stacktrace?

[ntsekouras]

the whole stacktrace is this:

System.ArgumentNullException: Value cannot be null.

Parameter name: builder
   at Microsoft.EntityFrameworkCore.Utilities.Check.NotNull[T](T value, String parameterName)
   at Microsoft.EntityFrameworkCore.Metadata.Builders.ReferenceReferenceBuilder..ctor(InternalRelationshipBuilder builder, EntityType declaringEntityType, EntityType relatedEntityType)
   at Microsoft.EntityFrameworkCore.Metadata.Builders.ReferenceReferenceBuilder`2..ctor(InternalRelationshipBuilder builder, EntityType declaringEntityType, EntityType relatedEntityType)
   at Microsoft.EntityFrameworkCore.Metadata.Builders.ReferenceNavigationBuilder`2.WithOne(Expression`1 reference)
   at Decisions.EntityFramework.DecisionsDbContext.OnModelCreating(ModelBuilder modelBuilder) in C:\Projects\Decisions\src\src\Decisions.EntityFramework\DecisionsDbContext.cs:line 155
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelCustomizer.Customize(ModelBuilder modelBuilder, DbContext dbContext)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.CreateModel(DbContext context, IConventionSetBuilder conventionSetBuilder, IModelValidator validator)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.<>c__DisplayClass14_0.<GetModel>b__0(Object k)
   at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.GetModel(DbContext context, IConventionSetBuilder conventionSetBuilder, IModelValidator validator)

   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.CreateModel()

   at Microsoft.EntityFrameworkCore.Internal.LazyRef`1.get_Value()

   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.get_Model()

   at Microsoft.EntityFrameworkCore.Infrastructure.EntityFrameworkServiceCollectionExtensions.<>c.<AddEntityFramework>b__0_4(IServiceProvider p)

   at lambda_method(Closure , ServiceProvider )

   at Microsoft.Extensions.DependencyInjection.ServiceProvider.GetService(Type serviceType)

   at Microsoft.Extensions.DependencyInjection.ServiceProviderExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)

   at Microsoft.Extensions.DependencyInjection.ServiceProviderExtensions.GetRequiredService[T](IServiceProvider provider)

   at Microsoft.EntityFrameworkCore.DbContext.get_Model()

   at Microsoft.EntityFrameworkCore.DbContext.Set[TEntity]()

   at EgritosGroup.EntityFramework.Repositories.EfRepositoryBase`3.get_Table()

   at EgritosGroup.EntityFramework.Repositories.EfRepositoryBase`3.GetAll()

   at EgritosGroup.Core.Domain.Repositories.EgfRepositoryBase`2.FirstOrDefault(TPrimaryKey id)

   at EgritosGroup.Core.Domain.Repositories.EgfRepositoryBase`2.Get(TPrimaryKey id)

   at Decisions.Bll.Sessions.SessionAppService.<Get>d__10.MoveNext() in C:\Projects\Decisions\src\src\Decisions.Bll\Sessions\SessionAppService.cs:line 101

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()

   at Decisions.WebUi.Controllers.SessionsController.<GetSession>d__6.MoveNext() in C:\Projects\Decisions\src\src\Decisions.WebUi\Controllers\SessionsController.cs:line 78

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()

   at Microsoft.AspNetCore.Mvc.Internal.ObjectMethodExecutor.<CastToObject>d__24`1.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()

   at Microsoft.AspNetCore.Mvc.Internal.ControllerActionInvoker.<InvokeActionAsync>d__6.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()

   at Microsoft.AspNetCore.Mvc.Internal.FilterActionInvoker.<InvokeActionFilterAsync>d__41.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()

   at Microsoft.AspNetCore.Mvc.Internal.FilterActionInvoker.<InvokeAsync>d__32.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()

   at Microsoft.AspNetCore.Mvc.Internal.MvcRouteHandler.<InvokeActionAsync>d__8.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()

   at Microsoft.AspNetCore.Builder.RouterMiddleware.<Invoke>d__4.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()

   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware`1.<Invoke>d__18.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()

   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware`1.<Invoke>d__18.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()

   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware`1.<Invoke>d__18.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()

   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware`1.<Invoke>d__18.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()

   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware`1.<Invoke>d__18.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()

   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware`1.<Invoke>d__18.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()

   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware`1.<Invoke>d__18.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()

   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware`1.<Invoke>d__18.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()

   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.MigrationsEndPointMiddleware.<Invoke>d__5.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()

   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.<Invoke>d__6.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()

   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.<Invoke>d__6.MoveNext()

--- End of stack trace from previous location where exception was thrown ---

   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)

   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()

   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.<Invoke>d__7.MoveNext()