Put models folder into a new project named DataAccessSample from SwaggerODataSample solution

Hi,

I have a bug in my demo when I use SwaggerODataSample(aspnetcore),and I do not know how to do with the DI of my new project DataAccessSample into startup.cs.

### The log is: System.NullReferenceException: Object reference not set to an instance of an object. at Microsoft.AspNet.OData.TypeExtensions.<>c__DisplayClass23_0.<GetStructuredType>b__0(IEdmStructuredType t) in C:\Users\Fusionshen\Downloads\aspnet-api-versioning\src\Common.OData.ApiExplorer\AspNet.OData\TypeExtensions.cs:line 137 at System.Linq.Enumerable.TryGetFirst[TSource](IEnumerable1 source, Func2 predicate, Boolean& found) at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable1 source, Func2 predicate) at Microsoft.AspNet.OData.TypeExtensions.GetStructuredType(Type type, IEdmModel model, IEnumerable1 assemblies) in C:\Users\Fusionshen\Downloads\aspnet-api-versioning\src\Common.OData.ApiExplorer\AspNet.OData\TypeExtensions.cs:line 137 at Microsoft.AspNet.OData.TypeExtensions.SubstituteIfNecessary(Type type, IServiceProvider serviceProvider, IEnumerable1 assemblies, ModelTypeBuilder modelTypeBuilder) in C:\Users\Fusionshen\Downloads\aspnet-api-versioning\src\Common.OData.ApiExplorer\AspNet.OData\TypeExtensions.cs:line 53 at Microsoft.AspNetCore.Mvc.ApiExplorer.ODataApiDescriptionProvider.GetApiResponseTypes(IReadOnlyList1 responseMetadataAttributes, Type responseType, IServiceProvider serviceProvider) in C:\Users\Fusionshen\Downloads\aspnet-api-versioning\src\Microsoft.AspNetCore.OData.Versioning.ApiExplorer\AspNetCore.Mvc.ApiExplorer\ODataApiDescriptionProvider.cs:line 556 at Microsoft.AspNetCore.Mvc.ApiExplorer.ODataApiDescriptionProvider.<NewODataApiDescriptions>d__33.MoveNext() in C:\Users\Fusionshen\Downloads\aspnet-api-versioning\src\Microsoft.AspNetCore.OData.Versioning.ApiExplorer\AspNetCore.Mvc.ApiExplorer\ODataApiDescriptionProvider.cs:line 324 at Microsoft.AspNetCore.Mvc.ApiExplorer.ODataApiDescriptionProvider.OnProvidersExecuted(ApiDescriptionProviderContext context) in C:\Users\Fusionshen\Downloads\aspnet-api-versioning\src\Microsoft.AspNetCore.OData.Versioning.ApiExplorer\AspNetCore.Mvc.ApiExplorer\ODataApiDescriptionProvider.cs:line 172 at Microsoft.AspNetCore.Mvc.ApiExplorer.ApiDescriptionGroupCollectionProvider.GetCollection(ActionDescriptorCollection actionDescriptors) at Microsoft.AspNetCore.Mvc.ApiExplorer.ApiDescriptionGroupCollectionProvider.get_ApiDescriptionGroups() at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GetSwagger(String documentName, String host, String basePath, String[] schemes) at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.<Invoke>d__6.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.AspNetCore.Builder.RouterMiddleware.<Invoke>d__4.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.AspNetCore.Hosting.Internal.RequestServicesContainerMiddleware.<Invoke>d__3.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.Frame1.<ProcessRequestsAsync>d__2.MoveNext() ### The bug location:

It seems that the DI of my new project DataAccessSample is not ok.

what can I do?

Regards

[commonsensesoftware]

I’ve been able to confirm this is actually a bug that occurs in two parts:

1. When the model type is a different assembly it may not be automatically added to the AssemblyPartManager, which is how assemblies are discovered by default
2. It is [falsely] assumed that a model type should be mapped to a CLR type from the available assemblies. This may not be true when part 1 is true, making the CLR type undiscoverable, and can actually result in a NullReferenceException.

I should have both of these issues fixed shortly and published in the next release.

In the meantime, you can work around the issue as @spasarto suggested or simply change line 27 in your example to:

services.AddMvc().AddApplicationPart(typeof(Order).Assembly);

[commonsensesoftware]

Good point @spasarto. That could be why it’s not being automatically detected. If that’s truly the issue, there are two ways to deal with it. Option 1 is exactly as @spasarto suggests. Option 2 is that you can add to the model builder before you build the models. Dependency Injection is a convenience and not a requirement for things to work.

Either of the following are valid:

public void Configure( IApplicationBuilder app )
{
  var modelBuilder = new VersionedODataModelBuilder()
  {
      ModelConfigurations =
      {
          new PersonModelConfiguration()
      }
  };
  var models = modelBuilder.GetEdmModels();
  app.UseMvc( routes => routes.MapVersionedODataRoutes( "odata", default, models ) );
}

Figure 1: Imperatively create a model builder without any Dependency Injection

public void Configure( IApplicationBuilder app, VersionedODataModelBuilder modelBuilder )
{
  modelBuilder.ModelConfigurations.Add( new PersonModelConfiguration() );
  var models = modelBuilder.GetEdmModels();
  app.UseMvc( routes => routes.MapVersionedODataRoutes( "odata", default, models ) );
}

Figure 2: Add to a model builder supplied via Dependency Injection