NSwag Not Recognizing Custom Authorization Attributes

Question

Currently having a problem with NSwag generation on a custom authorize attribute. I have been completely unable to find anything on this issue elsewhere.

I've created a custom attribute for my WebAPI and more or less followed the patterns recommended here

internal class AuthorizeWithPermissionAttribute : AuthorizeAttribute
{
    const string POLICY_PREFIX = "HasPermission";
    public AuthorizeWithPermissionAttribute(string permission) { // logic excluded for brevity }

    public string Permission 
    { 
        get { // code }
        set { // code }
    }
}

Then I decorate my controller with this attribute like so

[AuthorizeWithPermission("MY_PERMISSION_NAME")]
public class MyController: ControllerBase
{
  // Controller logic.
}

So far I have tried

• Creating a public parameterless constructor on the attribute
• Changing the type (enum, int, string) of the constructor param
• Applying [OpenApiIgnore] to the type and then writing a custom filter in Startup.cs when that didn't work
• Changing the access modifier at the class and property level
• Applying the attribute broadly to the controller and methods directly.

Here is the error I'm getting:

Executing file 'nswag.json' with variables 'Configuration=Debug'...
3>    Launcher directory: %UserDirectory%\.nuget\packages\nswag.msbuild\13.8.2\tools\NetCore31
3>    System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
3>     ---> System.NullReferenceException: Object reference not set to an instance of an object.
3>       at %SLNNAME%.Authorization.Attributes.AuthorizeWithPermissionAttribute..ctor(String permission) in %SLNDirectory%\Authorization\Attributes\AuthorizeWithPermissionAttribute.cs:line 14
3>       at System.Reflection.CustomAttribute._CreateCaObject(RuntimeModule pModule, RuntimeType type, IRuntimeMethodInfo pCtor, Byte** ppBlob, Byte* pEndBlob, Int32* pcNamedArgs)
3>       at System.Reflection.CustomAttribute.CreateCaObject(RuntimeModule module, RuntimeType type, IRuntimeMethodInfo ctor, IntPtr& blob, IntPtr blobEnd, Int32& namedArgs)
3>       at System.Reflection.CustomAttribute.AddCustomAttributes(ListBuilder`1& attributes, RuntimeModule decoratedModule, Int32 decoratedMetadataToken, RuntimeType attributeFilterType, Boolean mustBeInheritable, ListBuilder`1 derivedAttributes)
3>       at System.Reflection.CustomAttribute.GetCustomAttributes(RuntimeModule decoratedModule, Int32 decoratedMetadataToken, Int32 pcaCount, RuntimeType attributeFilterType)
3>       at System.Reflection.CustomAttribute.GetCustomAttributes(RuntimeType type, RuntimeType caType, Boolean inherit)
3>       at System.RuntimeType.GetCustomAttributes(Boolean inherit)
3>       at Microsoft.AspNetCore.Mvc.ApplicationModels.DefaultApplicationModelProvider.CreateControllerModel(TypeInfo typeInfo)
3>       at Microsoft.AspNetCore.Mvc.ApplicationModels.DefaultApplicationModelProvider.OnProvidersExecuting(ApplicationModelProviderContext context)
3>       at Microsoft.AspNetCore.Mvc.ApplicationModels.ApplicationModelFactory.CreateApplicationModel(IEnumerable`1 controllerTypes)
3>       at Microsoft.AspNetCore.Mvc.ApplicationModels.ControllerActionDescriptorProvider.GetDescriptors()
3>       at Microsoft.AspNetCore.Mvc.ApplicationModels.ControllerActionDescriptorProvider.OnProvidersExecuting(ActionDescriptorProviderContext context)
3>       at Microsoft.AspNetCore.Mvc.Infrastructure.DefaultActionDescriptorCollectionProvider.UpdateCollection()
3>       at Microsoft.AspNetCore.Mvc.Infrastructure.DefaultActionDescriptorCollectionProvider.Initialize()
3>       at Microsoft.AspNetCore.Mvc.Infrastructure.DefaultActionDescriptorCollectionProvider.get_ActionDescriptors()
3>       at Microsoft.AspNetCore.Mvc.ApiExplorer.ApiDescriptionGroupCollectionProvider.get_ApiDescriptionGroups()
3>       at NSwag.Generation.AspNetCore.AspNetCoreOpenApiDocumentGenerator.GenerateAsync(Object serviceProvider)
3>       at NSwag.AspNetCore.OpenApiDocumentProvider.GenerateAsync(String documentName)
3>       at NSwag.Commands.Generation.AspNetCore.AspNetCoreToSwaggerCommand.GenerateDocumentWithDocumentProviderAsync(IServiceProvider serviceProvider) in C:\projects\nswag\src\NSwag.Commands\Commands\Generation\AspNetCore\AspNetCoreToOpenApiCommand.cs:line 287
3>       at NSwag.Commands.Generation.AspNetCore.AspNetCoreToSwaggerCommand.GenerateDocumentAsync(AssemblyLoader assemblyLoader, IServiceProvider serviceProvider, String currentWorkingDirectory) in C:\projects\nswag\src\NSwag.Commands\Commands\Generation\AspNetCore\AspNetCoreToOpenApiCommand.cs:line 276
3>       at NSwag.Commands.Generation.AspNetCore.AspNetCoreToOpenApiGeneratorCommandEntryPoint.<>c__DisplayClass0_0.<<Process>b__0>d.MoveNext() in C:\projects\nswag\src\NSwag.Commands\Commands\Generation\AspNetCore\AspNetCoreToOpenApiGeneratorCommandEntryPoint.cs:line 30
3>    --- End of stack trace from previous location where exception was thrown ---
3>       at NSwag.Commands.Generation.AspNetCore.AspNetCoreToOpenApiGeneratorCommandEntryPoint.Process(String commandContent, String outputFile, String applicationName) in C:\projects\nswag\src\NSwag.Commands\Commands\Generation\AspNetCore\AspNetCoreToOpenApiGeneratorCommandEntryPoint.cs:line 29
3>       --- End of inner exception stack trace ---
3>       at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor, Boolean wrapExceptions)
3>       at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
3>       at System.Reflection.MethodBase.Invoke(Object obj, Object[] parameters)
3>       at NSwag.AspNetCore.Launcher.Program.Main(String[] args) in C:\projects\nswag\src\NSwag.AspNetCore.Launcher\Program.cs:line 170
3>    System.InvalidOperationException: Swagger generation failed with non-zero exit code '1'.
3>       at NSwag.Commands.Generation.AspNetCore.AspNetCoreToSwaggerCommand.RunAsync(CommandLineProcessor processor, IConsoleHost host) in C:\projects\nswag\src\NSwag.Commands\Commands\Generation\AspNetCore\AspNetCoreToOpenApiCommand.cs:line 221
3>       at NSwag.Commands.NSwagDocumentBase.GenerateSwaggerDocumentAsync() in C:\projects\nswag\src\NSwag.Commands\NSwagDocumentBase.cs:line 280
3>       at NSwag.Commands.NSwagDocument.ExecuteAsync() in C:\projects\nswag\src\NSwag.Commands\NSwagDocument.cs:line 81
3>       at NSwag.Commands.Document.ExecuteDocumentCommand.ExecuteDocumentAsync(IConsoleHost host, String filePath) in C:\projects\nswag\src\NSwag.Commands\Commands\Document\ExecuteDocumentCommand.cs:line 86
3>       at NSwag.Commands.Document.ExecuteDocumentCommand.RunAsync(CommandLineProcessor processor, IConsoleHost host) in C:\projects\nswag\src\NSwag.Commands\Commands\Document\ExecuteDocumentCommand.cs:line 32
3>       at NConsole.CommandLineProcessor.ProcessSingleAsync(String[] args, Object input)
3>       at NConsole.CommandLineProcessor.ProcessAsync(String[] args, Object input)
3>       at NConsole.CommandLineProcessor.Process(String[] args, Object input)
3>       at NSwag.Commands.NSwagCommandProcessor.Process(String[] args) in C:\projects\nswag\src\NSwag.Commands\NSwagCommandProcessor.cs:line 56
3>    %SLNDirectory%.csproj(59,5): error MSB3073: The command "dotnet "%UserDirectory%\.nuget\packages\nswag.msbuild\13.8.2\build\../tools/NetCore31/dotnet-nswag.dll" run nswag.json /variables:Configuration=Debug" exited with code -1.
3>  Done executing task "Exec" -- FAILED.

Answer 1

LOGIC! LOGIC IN The constructor was the issue. Here this works. Hopefully someone won't spend two hours of their life on this like I did

public class AuthorizeWithPermissionAttribute : AuthorizeAttribute
{
    const string POLICY_PREFIX = "HasPermission";
    public AuthorizeWithPermissionAttribute(string permission)
    {
       this.Permission = permission;
    }

    public string Permission { get => Policy; set => Policy = $"{POLICY_PREFIX}{value}"; }
}