您可以通过使用的UserManager获得用户并分配角色。

You can get user and assigned roles by using UserManager.

var userManager = HttpContext.GetOwinContext().GetUserManager<ApplicationUserManager>();

，然后你可以得到你的用户喜欢你已经做了，也可以通过调用方法getRoles获取特定的用户角色

and then you can get your user like you already did, and also you can get roles for particular user by calling GetRoles method

userManager.GetRoles(userId);