Swagger 在 OWIN Startup Web API C# 中不起作用答案

【问题标题】：Swagger isn't working in OWIN Startup Web API C#Swagger 在 OWIN Startup Web API C# 中不起作用
【发布时间】：2020-12-09 14:17:00
【问题描述】：

我在我的 Web API 的 OWIN startup.cs 文件中实现了 Swagger，但是当我尝试打开 Swagger UI 页面时，它显示 HTTP Error 404.0 - Not Found

检查 Swagger UI 的 URL：https://localhost:5001/swagger

这是我的实现，请帮我解决我所缺少的。

Startup.cs

public class Startup
{
   public void Configuration(IAppBuilder app)
   {
     app.Map("/api", map => { ConfigureApiArea(map); });
   }

   private void ConfigureApiArea(IAppBuilder map)
   {
            var config = CreateTypedConfiguration<BaseApiController>();

            //Json Settings
            JsonFormatterSettings(config);

            ConfigureAutofac(config, map);
            ConfigureOAuth(map);

            config.EnableCors(new EnableCorsAttribute("*", "*", "*", "Paging-Headers,X-Error"));
            map.UseCors(Microsoft.Owin.Cors.CorsOptions.AllowAll);
            config.EnsureInitialized();


            map.UseWebApi(config);
   }

   private HttpConfiguration CreateTypedConfiguration<TBaseController>() where TBaseController : IHttpController
   {
            var config = new HttpConfiguration();
            config.Services.Replace(typeof(IHttpControllerTypeResolver), new 
            TypedHttpControllerTypeResolver<TBaseController>());
            config.EnableSwagger();
            config.MapHttpAttributeRoutes(new TypedDirectRouteProvider<TBaseController>());
            return config;
   }

}

SwaggerExtensions.cs

 public static class SwaggerExtensions
    {
        public static HttpConfiguration EnableSwagger(this HttpConfiguration httpConfiguration)
        {
            httpConfiguration
                .EnableSwagger(c => c.SingleApiVersion("v1", "MyWebAPI"))
                .EnableSwaggerUi();

            return httpConfiguration;
        }
    }

MyController.cs

public class MyController : BaseApiController
{
    [AllowAnonymous]
    [HttpGet]
    [Route("orders/{orderId}")]
    public IHttpActionResult GetOrder([FromUri]string orderId) {
        return Ok();
    }
}

BaseApiController.cs

 public class BaseApiController : ApiController { }

【问题讨论】：

你试过https://localhost:5001/api/swagger吗？
是的，我做了 localhost:5001/api/swagger 和 localhost:5001/api/swagger/ui，但还是没有相同的 404

标签： c# asp.net-web-api swagger owin swagger-ui

【解决方案1】：

事实上https://localhost:5001/api/swagger正如@Dai所建议的那样，它不起作用的原因是因为方法ConfigureAutofac(config, map)中的自定义MessageHandlers（OP在代码中没有显示）没有处理请求包含/swagger 的路径。

方法ConfigureAutofac(config, map)内的MessageHandler代码省略：

private void ConfigureAutofac(HttpConfiguration config, IAppBuilder app)
{
    var builder = new ContainerBuilder();    
    
    //code omitted for brevity ...

    //Register Web API controllers.
    builder.RegisterApiControllers(Assembly.GetExecutingAssembly())
    .InstancePerRequest();

    //Register the Autofac filter provider.
    builder.RegisterWebApiFilterProvider(config);

    //Register the Autofac model binder provider.
    builder.RegisterWebApiModelBinderProvider();

    //code omitted for brevity ...
    
    var container = builder.Build();

    //Set the dependency resolver to be Autofac.
    config.DependencyResolver = new AutofacWebApiDependencyResolver(container);
    config.MessageHandlers.Insert(0, new ApiDelegatingHandler());
    config.MessageHandlers.Insert(1, new ActivityLogHandler());

    app.UseAutofacMiddleware(container);
    app.UseAutofacWebApi(config);
}

自定义MessageHandler 中唯一需要的更改是处理此问题，如下所示：

public class ApiDelegatingHandler : DelegatingHandler
{
    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        if (request.RequestUri.PathAndQuery.Contains("/swagger")) 
            return await base.SendAsync(request, cancellationToken);

        //code omitted for brevity ...
    }
}

【讨论】：