如何使用 [SwaggerOperationFilter] 的依赖注入？

Question

我正在使用 Swashbuckle 为我的网站实施 OpenAPI 文档 api。我决定在我的一项操作中使用 [SwaggerOperationFilter] 属性，以改进其响应主体示例。

根据 the documentation，Swashbuckle 的过滤器管道可以使用依赖注入，如下摘录：

NOTE: Filter pipelines are DI-aware. That is, you can create filters with constructor parameters and if the parameter types are registered with the DI framework, they'll be automatically injected when the filters are instantiated

这是控制器的简化版本

/// <summary>Some sample controller.</summary>
[ApiController]
[Route("/my-controller")]
public class MyController : ControllerBase {
    /// <summary>Simple action returning some string array.</summary>
    /// <response code="200">All went well.</response>
    [HttpGet]
    [SwaggerOperationFilter(typeof(MyOperationFilter))]
    public IEnumerable<string> GetSomeStrings() => new[] { "abc", "def" };
}

和我正在尝试实现的IOperationFilter：

public class MyOperationFilter : IOperationFilter {
    public MyOperationFilter(ILogger<MyOperationFilter> logger) {   // <--- Dependency Injection will fail to call this constructor
        logger.LogInformation("DI won't work!");
    }


    public void Apply(OpenApiOperation operation, OperationFilterContext context) {
        var responseExample = new OpenApiArray();
        responseExample.AddRange(new [] {
            new OpenApiString("text-1"),
            new OpenApiString("text-2"),
            new OpenApiString("text-3"),
        });

        var response = operation.Responses["200"];
        response.Content["application/json"].Example = responseExample;
    }
}

此代码在尝试访问 OpenAPI 文档和 Swagger UI 时无法执行，但出现以下异常：

MyProject.MyControllers.UnhandledExceptionsController[0]
      Unhandled exception of type SwaggerGeneratorException on path "/api-docs/my-api-v1/openapi.json"
      Swashbuckle.AspNetCore.SwaggerGen.SwaggerGeneratorException: Failed to generate Operation for action - MyProject.MyControllers.MyController.GetSomeStrings (my-project). See inner exception  
       ---> System.MissingMethodException: No parameterless constructor defined for type 'MyProject.MyControllers.MyOperationFilter'.
         at System.RuntimeType.CreateInstanceDefaultCtorSlow(Boolean publicOnly, Boolean wrapExceptions, Boolean fillCache)
         at System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, Boolean wrapExceptions)
         at System.Activator.CreateInstance(Type type, Boolean nonPublic, Boolean wrapExceptions)
         at Swashbuckle.AspNetCore.Annotations.AnnotationsOperationFilter.ApplySwaggerOperationFilterAttributes(OpenApiOperation operation, OperationFilterContext context, IEnumerable`1 controllerAndActionAttributes)
         at Swashbuckle.AspNetCore.Annotations.AnnotationsOperationFilter.Apply(OpenApiOperation operation, OperationFilterContext context)
         at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateOperation(ApiDescription apiDescription, SchemaRepository schemaRepository)
         --- End of inner exception stack trace ---
         at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateOperation(ApiDescription apiDescription, SchemaRepository schemaRepository)
         at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateOperations(IEnumerable`1 apiDescriptions, SchemaRepository schemaRepository)
         at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GeneratePaths(IEnumerable`1 apiDescriptions, SchemaRepository schemaRepository)
         at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GetSwagger(String documentName, String host, String basePath)
         at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)
         at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.<Invoke>g__Awaited|6_0(ExceptionHandlerMiddleware middleware, HttpContext context, Task task)

我知道如果我在 services.AddSwagerGen(...) 调用中注册 IOperationFilter，我的操作过滤器 将启用 DI。但是这种方法的问题是注册的 IOperationFilter 将被注册为“全局”过滤器，并将应用于我项目中的每个操作方法，我想避免这种情况，因为这个过滤器应该影响我项目中的单个操作方法。

有没有办法继续使用本地（“非全局”）IOperationFilter（通过 [SwaggerOperationFilter]）并让我的过滤器注入依赖项？

Answer 1

Is there any way to keep using a local ("non-global") IOperationFilter (via [SwaggerOperationFilter]) and have my filter injected with dependencies?

不是按照他们的source code

AnnotationsOperationFilter

//...

public static void ApplySwaggerOperationFilterAttributes(
    OpenApiOperation operation,
    OperationFilterContext context,
    IEnumerable<object> controllerAndActionAttributes)
{
    var swaggerOperationFilterAttributes = controllerAndActionAttributes
        .OfType<SwaggerOperationFilterAttribute>();

    foreach (var swaggerOperationFilterAttribute in swaggerOperationFilterAttributes)
    {
        var filter = (IOperationFilter)Activator.CreateInstance(swaggerOperationFilterAttribute.FilterType);
        filter.Apply(operation, context);
    }
}

//...

可以看出他们使用了 Activator.CreateInstance，这需要一个默认构造函数，正如在给定异常的堆栈跟踪中所指出的那样。

如何使用 [SwaggerOperationFilter] 的依赖注入？

How to use Dependency Injection with [SwaggerOperationFilter]?

c#

asp.net-core

swagger

openapi

swashbuckle