会话变量值在ASP.NET Core中变为null

Question

我在一个方法中设置一个会话变量，并尝试从控制器中的另一个方法获取会话变量值，但它始终为null：

这是我的代码：

public class HomeController : Controller
{
    public IActionResult Index()
    { 
        HttpContext.Session.SetString("Test", "Hello!");
        var message = HttpContext.Session.GetString("Test");// Here value is getting correctly
        return View();
    }

    public IActionResult About()
    {
        var message = HttpContext.Session.GetString("Test"); // This value is always getting null here

        return View();
    }
}

这是我在Startup类中的会话配置：

在ConfigureServices()方法：

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

services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
services.AddDistributedMemoryCache();
services.AddMvc().AddSessionStateTempDataProvider();
services.AddSession(options =>
{
    options.Cookie.Name = "TanvirArjel.Session";
    options.IdleTimeout = TimeSpan.FromDays(1);
});

在Configure()方法：

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

非常奇怪和特殊的问题！任何帮助将非常感谢！

Answer 1

对于ASP.NET Core 2.1和2.2

在Startup类的ConfigureServices方法中，设置options.CheckConsentNeeded = context => false;如下：

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;
});

问题解决了！

Answer 2

您也可以按照此处的说明设置Cookie.IsEssential = true：https://andrewlock.net/session-state-gdpr-and-non-essential-cookies/

有一个services.AddSession()超载，允许您在SessionOptions文件中配置Startup。您可以更改会话超时等各种设置，还可以自定义会话cookie。要将cookie标记为必要，请将IsEssential设置为true：

public void ConfigureServices(IServiceCollection services)
{
    services.Configure<CookiePolicyOptions>(options =>
    {
        options.CheckConsentNeeded = context => true; // consent required
        options.MinimumSameSitePolicy = SameSiteMode.None;
    });

    services.AddSession(opts => 
    {
        opts.Cookie.IsEssential = true; // make the session cookie Essential
    });
    services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
}