在 asp.net 5.0 web api 项目中访问中间件中的 TempData

Question

我有两个应用程序同时运行。我试图找到一种能够在我自己的类中使用TempData 的方法，在阅读它之后，我在我的中间件中为我的 MVC 项目实现了它，该项目运行顺利。但是，当我将 MVC 项目中的中间件代码复制到我的 asp.net web api 项目的中间件时，它不起作用。当我一起运行程序时，当它调用 web api 项目时，它返回以下 web api（MVC 工作正常，我没有得到任何错误）：

InvalidOperationException：尝试激活“AddressService.API.Middleware.CorrelationIdMiddleware”时，无法解析“Microsoft.AspNetCore.Mvc.ViewFeatures.ITempDataDictionaryFactory”类型的服务。

在我在我的 web api 项目的中间件中实现 TempData (ITempDataDictionaryFactory) 之前，它运行良好......但在实现 ITempDataDictionaryFactory 之后，它给了我这个错误。我必须做些什么才能让它像在我的 MVC 项目的中间件中那样工作吗？

Middleware 在我的 web api 项目中：

    public class CorrelationIdMiddleware
    {
        private readonly RequestDelegate _next;
        private readonly ILogger _logger;
        private readonly ITempDataDictionaryFactory _tempDataDictionaryFactory;
        public CorrelationIdMiddleware(RequestDelegate next, ILoggerFactory loggerFactory, ITempDataDictionaryFactory tempDataDictionaryFactory)
        {
            _next = next;
            _logger = loggerFactory.CreateLogger<CorrelationIdMiddleware>();
            _tempDataDictionaryFactory = tempDataDictionaryFactory;
        }

        public async Task Invoke(HttpContext context)
        {
            string correlationId = null;
            string userName;
            string ipAddress;

            var tempData = _tempDataDictionaryFactory.GetTempData(context);

            var key = context.Request.Headers.Keys.FirstOrDefault(n => n.ToLower().Equals("x-correlation-id"));
            if (!string.IsNullOrWhiteSpace(key))
            {
                correlationId = context.Request.Headers[key];
                _logger.LogInformation("Header contained CorrelationId: {@CorrelationId}", correlationId);
            }
            else
            {
                if (tempData.ContainsKey("username") && tempData.ContainsKey("ipaddress"))
                {
                    userName = tempData.Peek("username").ToString();

                    ipAddress = tempData.Peek("ipaddress").ToString();

                    context.Response.Headers.Append("X-username", userName);
                    context.Response.Headers.Append("X-ipAddress", ipAddress);
                }

                correlationId = Guid.NewGuid().ToString();
                _logger.LogInformation("Generated new CorrelationId: {@CorrelationId}", correlationId);
            }
            context.Response.Headers.Append("x-correlation-id", correlationId);
            using (LogContext.PushProperty("CorrelationId", correlationId))
            {
                await _next.Invoke(context);
            }
        }

CorrelationIdExtensions.cs（用于在启动时调用app.UseCorrelationId()）：

public static class CorrelationIdExtensions
{
    public static IApplicationBuilder UseCorrelationId(this IApplicationBuilder builder)
    {
        return builder.UseMiddleware<CorrelationIdMiddleware>();
    }
}

Startup.cs:

    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "AddressService.API", Version = "v1" });
            });

           services.AddHttpContextAccessor();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            app.UseCorrelationId();

            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseSwagger();
                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "AddressService.API v1"));
            }

            app.UseHttpsRedirection();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }

Answer 1

解决这个问题的方法之一应该是使用：

services.AddControllersWithViews();

或

services.AddMvc();

而不是services.AddControllers();。