“/”应用程序中的服务器错误。

Question

“/”应用程序中的服务器错误。
未将对象引用设置到对象的实例。
说明: 执行当前 Web 请求期间，出现未经处理的异常。请检查堆栈跟踪信息，以了解有关该错误以及代码中导致错误的出处的详细信息。

异常详细信息: System.NullReferenceException: 未将对象引用设置到对象的实例。

源错误:

行 30: //}
行 31:
行 32: if (Session["Carts"] == null)
行 33: {
行 34: Session["Carts"] = new List();

源文件: d:\Documents\Visual Studio 2013\Projects\大电的城\大电的城\Controllers\BaseController.cs 行: 32

堆栈跟踪:

[NullReferenceException: 未将对象引用设置到对象的实例。]
大电的城.Controllers.BaseController.get_Carts() in d:\Documents\Visual Studio 2013\Projects\大电的城\大电的城\Controllers\BaseController.cs:32
大电的城.Controllers.BaseController..ctor() in d:\Documents\Visual Studio 2013\Projects\大电的城\大电的城\Controllers\BaseController.cs:78
大电的城.Controllers.HomeController..ctor() in d:\Documents\Visual Studio 2013\Projects\大电的城\大电的城\Controllers\HomeController.cs:28

[TargetInvocationException: 调用的目标发生了异常。]
System.RuntimeTypeHandle.CreateInstance(RuntimeType type, Boolean publicOnly, Boolean noCheck, Boolean& canBeCached, RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck) +0
System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +113
System.RuntimeType.CreateInstanceDefaultCtor(Boolean publicOnly, Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +206
System.Activator.CreateInstance(Type type, Boolean nonPublic) +83
System.Activator.CreateInstance(Type type) +11
System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +55

[InvalidOperationException: 尝试创建“大电的城.Controllers.HomeController”类型的控制器时出错。请确保控制器具有无参数公共构造函数。]
System.Web.Mvc.DefaultControllerActivator.Create(RequestContext requestContext, Type controllerType) +179
System.Web.Mvc.DefaultControllerFactory.GetControllerInstance(RequestContext requestContext, Type controllerType) +79
System.Web.Mvc.DefaultControllerFactory.CreateController(RequestContext requestContext, String controllerName) +74
System.Web.Mvc.MvcHandler.ProcessRequestInit(HttpContextBase httpContext, IController& controller, IControllerFactory& factory) +214
System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContextBase httpContext, AsyncCallback callback, Object state) +49
System.Web.Mvc.MvcHandler.BeginProcessRequest(HttpContext httpContext, AsyncCallback callback, Object state) +49
System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.BeginProcessRequest(HttpContext context, AsyncCallback cb, Object extraData) +18
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +103
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

public List Carts
{
get
{
if (User.Identity.IsAuthenticated)
{
int accountid = AccountBLL.GetAIDByUserName(User.Identity.Name);
//如果账户登陆了，“我的购物车”会显示所有已经在购物车里的商品
Session["Carts"] = BasketDetailBLL.GetAllList(accountid);

            }

            if (Session["Carts"] == null)
            {
                Session["Carts"] = new List<BasketDetail>();
            }

            return Session["Carts"] as List<BasketDetail>;

        }
        set
        {
            Session["Carts"] = value;
        }
    }

Answer 1

list li= new List();
Session["Carts"] =li;
这样写试试。