CustomClaimsTransformer中的IHttpContextAccessor会话无效操作异常

Question

我按照官方文档从CustomClaimsTransformer中的自定义组件访问HttpContext。背景，我以前有一个.net核心Web应用程序，我使用该会话使管理员能够使用不同用户的视图（身份）跳转到应用程序（出于支持目的）。我存储信息，应该在会话中为哪个用户准备视图。现在我想让它更优雅，并使用声明和基于角色的授权使用.net核心授权。由于后面有Windows身份验证，我将使用CustomClaimsTransformer。现在我的问题是，我想从CustomClaimsTransformer中访问当前会话。我可以注入IHttpContextAccessor，但IHttpContextAccessor.Session总是引发无效的操作异常。

Startup.cs：

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
            .AddCookie(CookieAuthenticationDefaults.AuthenticationScheme,
        options =>
        {
            options.LoginPath = new PathString("/Account/Login/");
            options.AccessDeniedPath = new PathString("/Account/Forbidden/");
        });
        services.Configure<CookiePolicyOptions>(options =>
        {
            options.CheckConsentNeeded = context => true;
            options.MinimumSameSitePolicy = SameSiteMode.None;
        });
        services.AddAuthorization(options =>
        {
            options.AddPolicy("RequireAdministratorRole", policy => policy.RequireClaim(ClaimTypes.Role, "admin"));
            options.AddPolicy("Test1", policy => policy.RequireClaim("Rechte", " Test1"));
            options.AddPolicy("Test2", policy => policy.RequireClaim("Rechte", " Test2"));

        });

        services.AddMvc(config =>
             {
                 var policy = new AuthorizationPolicyBuilder()
                    .RequireAuthenticatedUser()
                    .Build();
                 config.Filters.Add(new AuthorizeFilter(policy));
             }).SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
        //services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
        services.AddHttpContextAccessor();
        services.AddTransient<IClaimsTransformation, CustomClaimsTransformer>();
        services.AddDistributedMemoryCache();
        services.AddSession();
    }

CustomClaimsTransformer：

CustomClaimsTransformer:
public class CustomClaimsTransformer : IClaimsTransformation
{
    private readonly IHttpContextAccessor _httpContextAccessor;
    public CustomClaimsTransformer(IHttpContextAccessor httpContextAccessor)
    {
        _httpContextAccessor = httpContextAccessor;
    }


    public Task<ClaimsPrincipal> TransformAsync(ClaimsPrincipal principal)
    {
        var z = _httpContextAccessor.HttpContext; //works
        var zz = _httpContextAccessor.HttpContext.Session; // System.InvalidOperationException: "Session has not been configured for this application or request."

任何帮助都非常感谢

编辑1：

我在上面编辑了我的ConfigureServices，在粘贴代码时我删除了一些可读性的行，包括AddDistributedMemoryCache行，抱歉。会话正在应用程序中工作，除非显示。

配置：

        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        app.UseHttpsRedirection();
        app.UseStaticFiles();
        app.UseCookiePolicy();
        app.UseSession();

        app.UseAuthentication();

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

Answer 1

参考Session and app state in ASP.NET Core

要启用会话中间件，Startup必须包含：

• 任何IDistributedCache内存缓存。 IDistributedCache实现用作会话的后备存储。
• 在AddSession打电话给ConfigureServices。
• 在UseSession打电话给Configure。

也

public void Configure(IApplicationBuilder app, IHostingEnvironment env) {

    //... removed for brevity

    app.UseHttpsRedirection();
    app.UseStaticFiles();
    app.UseCookiePolicy();
    app.UseSession(); // This must come before "UseMvc()"
    app.UseHttpContextItemsMiddleware();
    app.UseMvc();
}

中间件的顺序很重要。在前面的示例中，在InvalidOperationException之后调用UseSession时会发生UseMvc异常。 ... 在调用HttpContext.Session之前无法访问UseSession。