ABP/Swashbuckle - Generating swagger docs using Swashbuckle CLI

Question

Using ABP Framework (3.3) and ASP.NET Core (3.1).

I'm attempting to generate swagger.json using Swashbuckle.AspNetCore.Cli (https://github.com/domaindrivendev/Swashbuckle.AspNetCore#retrieve-swagger-directly-from-a-startup-assembly) after compiling the application, pointing to the compiled dll using the following command:

dotnet swagger tofile --output "C:\temp\swagger" .\bin\Release\netcoreapp3.1\MyBin.dll v1

It gives me the below exception:

Unhandled exception. System.ArgumentNullException: Value cannot be null. (Parameter 'provider')
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
   at Microsoft.Extensions.DependencyInjection.ServiceCollectionCommonExtensions.GetRequiredService[T](IServiceCollection services)
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
   at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
   at System.Lazy`1.CreateValue()
   at System.Lazy`1.get_Value()
   at Volo.Abp.AspNetCore.Mvc.AbpDataAnnotationAutoLocalizationMetadataDetailsProvider.CreateDisplayMetadata(DisplayMetadataProviderContext context)
   at Microsoft.AspNetCore.Mvc.ModelBinding.Metadata.DefaultCompositeMetadataDetailsProvider.CreateDisplayMetadata(DisplayMetadataProviderContext context)
   at Microsoft.AspNetCore.Mvc.ModelBinding.Metadata.DefaultModelMetadata.get_DisplayMetadata()
   at Microsoft.AspNetCore.Mvc.ModelBinding.Metadata.DefaultModelMetadata.get_Order()
   at Microsoft.AspNetCore.Mvc.ModelBinding.Metadata.DefaultModelMetadata.<>c.<get_Properties>b__78_0(ModelMetadata p)
   at System.Linq.EnumerableSorter`2.ComputeKeys(TElement[] elements, Int32 count)
   at System.Linq.EnumerableSorter`1.ComputeMap(TElement[] elements, Int32 count)
   at System.Linq.EnumerableSorter`1.Sort(TElement[] elements, Int32 count)
   at System.Linq.OrderedEnumerable`1.ToList()
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Microsoft.AspNetCore.Mvc.ModelBinding.ModelPropertyCollection..ctor(IEnumerable`1 properties)
   at Microsoft.AspNetCore.Mvc.ModelBinding.Metadata.DefaultModelMetadata.get_Properties()
   at Microsoft.AspNetCore.Mvc.ModelBinding.ModelMetadataProviderExtensions.GetMetadataForProperty(IModelMetadataProvider provider, Type containerType, String propertyName)
   at Microsoft.AspNetCore.Mvc.ApplicationModels.DefaultApplicationModelProvider.CreatePropertyModel(PropertyInfo propertyInfo)
   at Microsoft.AspNetCore.Mvc.ApplicationModels.DefaultApplicationModelProvider.OnProvidersExecuting(ApplicationModelProviderContext context)
   at Microsoft.AspNetCore.Mvc.ApplicationModels.ApplicationModelFactory.CreateApplicationModel(IEnumerable`1 controllerTypes)
   at Microsoft.AspNetCore.Mvc.ApplicationModels.ControllerActionDescriptorProvider.GetDescriptors()
   at Microsoft.AspNetCore.Mvc.ApplicationModels.ControllerActionDescriptorProvider.OnProvidersExecuting(ActionDescriptorProviderContext context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.DefaultActionDescriptorCollectionProvider.UpdateCollection()
   at Microsoft.AspNetCore.Mvc.Infrastructure.DefaultActionDescriptorCollectionProvider.Initialize()
   at Microsoft.AspNetCore.Mvc.Infrastructure.DefaultActionDescriptorCollectionProvider.get_ActionDescriptors()
   at Microsoft.AspNetCore.Mvc.ApiExplorer.ApiDescriptionGroupCollectionProvider.get_ApiDescriptionGroups()
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GetSwagger(String documentName, String host, String basePath)
   at Swashbuckle.AspNetCore.Cli.Program.<>c.<Main>b__0_3(IDictionary`2 namedArgs) in C:\projects\ahoy\src\Swashbuckle.AspNetCore.Cli\Program.cs:line 72
   at Swashbuckle.AspNetCore.Cli.CommandRunner.Run(IEnumerable`1 args) in C:\projects\ahoy\src\Swashbuckle.AspNetCore.Cli\CommandRunner.cs:line 68
   at Swashbuckle.AspNetCore.Cli.CommandRunner.Run(IEnumerable`1 args) in C:\projects\ahoy\src\Swashbuckle.AspNetCore.Cli\CommandRunner.cs:line 68
   at Swashbuckle.AspNetCore.Cli.Program.Main(String[] args) in C:\projects\ahoy\src\Swashbuckle.AspNetCore.Cli\Program.cs:line 111

I've tried also creating a public class as per the Swashbuckle docs, as we are using Autofac:

    public class SwaggerHostFactory
    {
        public static IHost CreateHost()
        {
            return Program.CreateHostBuilder(new string[0]).Build(); //Calls the same builder that's used to run the app
        }
    }

The intent is to allow running this in our pipelines to auto-generate ApiClient libraries.

I'm at a bit of a loss as to how to resolve this. The swagger.json is generated at runtime perfectly fine?

Any help appreciated!

Answer 1

One way to avoid this is to make sure your program continues without these app settings

var connectionString = config["MyConnectionString"];
if (connectionString != null)
{
    services.AddDbContext<AppDbContext>(options =>
        options.UseSqlServer(connectionString));
}