c# - session 变量立即为空..ASP.net Core

Question

ASP.NET 核心 2.1

我在一个 Controller 中设置了一个 session 变量:

 public ActionResult setsession()
    {

       HttpContext.Session.SetString("name","Fozzy");

      return Ok();
    }

当我暂停调试器之后，我可以在此时看到 session 中的值
设置 session 变量。然后，我尝试通过 fetch 立即检索另一个 Controller 中的 session 变量，但它始终为空:

   public ActionResult getsession()
    {

        var fozzy =  HttpContext.Session.GetString("name");
        // fozzy is null
      return Ok(fozzy);
    }

我已将 session 超时设置为 20 分钟(我认为)

    services.AddSession(options =>
        {

            options.IdleTimeout = TimeSpan.FromMinutes(20);
        });

这是我的startup.cs:

      public void ConfigureServices(IServiceCollection services)
    {
        services.AddCors(options =>
        {
            options.AddPolicy("CorsPolicy", builder =>
                builder.AllowAnyOrigin()
                    .AllowAnyMethod()
                    .AllowAnyHeader()
                    .AllowCredentials());
        });

        services.Configure<CookiePolicyOptions>(options =>
        {
            // This lambda determines whether user consent for non-essential cookies is needed for a given request.
            options.CheckConsentNeeded = context => false;
            options.MinimumSameSitePolicy = SameSiteMode.None;
        });
        services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);

        services.AddDistributedMemoryCache();
        services.AddSession(options =>
        {

            options.IdleTimeout = TimeSpan.FromMinutes(20);
        });
        services.AddMvc().AddSessionStateTempDataProvider();

    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        app.UseCors("CorsPolicy");
        app.UseSession();
        app.UseMvc(routes =>
        {
            routes.MapRoute(
                name: "default",
                template: "{controller}/{action=Index}/{id?}");

            routes.MapSpaFallbackRoute(name: "spa-fallback",
                defaults: new { controller = "values", action = "Get" });
        });
        //if (env.IsDevelopment())
        //{
        //    app.UseDeveloperExceptionPage();
        //}
        //else
        //{
        //    app.UseExceptionHandler("/Home/Error");
        //    app.UseHsts();
        //}

        app.UseHttpsRedirection();
        app.UseStaticFiles();
        app.UseCookiePolicy();

        app.UseMvc(routes =>
        {
            routes.MapRoute(
                name: "default",
                template: "{controller=Home}/{action=Index}/{id?}");
        });
    }

我的问题不是设置 session 变量。我经历了那个噩梦。如果设置变量有问题，.Net Core 会抛出异常。我已经克服了这一切。

如何让我的 session 保留 ASP.net Core 2.1 中的值？谢谢

Answer 1

根据 the documentation on session state ，您需要按照三个步骤在 ASP.NET Core 中启用 session :

To enable the session middleware, Startup must contain:

• Any of the IDistributedCache memory caches. The IDistributedCache implementation is used as a backing store for session. For more information, see Distributed caching in ASP.NET Core.
• A call to AddSession in ConfigureServices.
• A call to UseSession in Configure.

所以除了 services.AddSession()设置一般 session 服务以便您可以一般访问它，您还需要执行 services.AddDistributedMemoryCache()为了有一些地方来存储数据。最后，内部 Configure您需要使用 app.UseSession() 设置 session 中间件确保在处理请求时读取 session 数据，以便您可以访问先前存储的数据。