如何从HttpContext获取OWinContext

Question

最近我们将旧的Membership更换为MVC中的ASP.NET Identity。 根据{{​​3}}进行 试图在“

”中获取“Ap​​plicationUserManager”实例

public void ConfigureAuth(IAppBuilder app)
{
    // Configure the db context, user manager and signin manager to use a single instance per request
    app.CreatePerOwinContext(ApplicationDbContext.Create);
    app.CreatePerOwinContext<IdentityUserManager>( ApplicationUserManager.Create);
    app.CreatePerOwinContext<ApplicationSignInManager>(ApplicationSignInManager.Create);

    UserManager = HttpContext.Current.GetOwinContext().GetUserManager< ApplicationUserManager >();
}

从Startup.cs调用哪个 但是，我收到一个例外：

 "No owin.Environment item was found in the context".

我在配置文件中添加了所有参数，如其他帖子中所述

<add key="owin:AutomaticAppStartup" value="true" />
<add key="owin:AppStartup" value="[namespace]Startup, [namespace]" />

以上启动命名空间：

[assembly: OwinStartup(typeof([namespace].Startup))]

还有其他建议吗？