c# - 使用枚举标志位的 WPF 基于权限的授权

Question

我已经使用 C# 一个月了，所以请原谅这个问题的“局部性”，但我已经研究了几个小时，但还是碰壁了。

我已经看到了使用 IIdentity 和 IPrincipal 的 WPF 应用程序的基于角色的授权示例。

我找不到很多信息，但是，关于更多基于权限的授权方法，在这个应用程序中想象没有组，只有权限和用户列表，你可以向任何人分配任何权限。

我希望能够:

1) 能够根据具有以下状态的用户权限控制 UI/元素:已启用、只读、不可见、已折叠(如此处所示 https://uiauth.codeplex.com/)
2) 能够在类或方法级别指定需要哪些权限(类似于 http://lostechies.com/derickbailey/2011/05/24/dont-do-role-based-authorization-checks-do-activity-based-checks/ )

代替:

[PrincipalPermission(SecurityAction.Demand, Role = "Administrators")]

我想要这样的东西:

[PrincipalPermission(SecurityAction.Demand, Permission = "可以添加用户")]

目前我看到的唯一方法是利用 ICommand 并将授权逻辑放入 CanExecute 方法中，使用大量字符串比较来查看用户是否具有执行请求的操作所需的权限，例如:

// Employee class
public bool HasRight(SecurityRight right)
{
    return employee.Permissions.Contains(right);
}

// Implementation, check if employee has right to continue
if (employee.HasRight(db.SecurityRights.Single(sr => sr.Description == "Can edit users")))
{
    // Allowed to perform action
}
else
{
    // User does not have right to continue
    throw SecurityException;
}

有人告诉我 Enum Flags 可能是我要找的东西 What does the [Flags] Enum Attribute mean in C#?

我想我理解 enum/flag/bits 但还不足以完成实现...

如果我有:

雇员模型
EmployeeViewModel
ThingTwoModel
ThingTwoViewModel
主视图

我不确定一切都去哪里以及如何将它们联系在一起......这是我到目前为止所拥有的(我意识到这不是一个有效的例子......那是我的问题!):

    [Flags]
    public enum Permissions
    {
        None = 0,
        Create = 1 << 0,
        Read = 1 << 1,
        Update = 1 << 2,
        Delete = 1 << 3,

        User = 1 << 4,
        Group = 1 << 5
    }

    public static void testFlag()
    {
        Permissions p;
        var x = p.HasFlag(Permissions.Update) && p.HasFlag(Permissions.User);
        var desiredPermissions = Permissions.User | Permissions.Read | Permissions.Create;
        if (x & p == desiredPermissions)
        {
            //the user can be created and read by this operator
        }
    }

感谢您的指导。

Answer 1

好吧，testFlag 不会按原样工作。我认为您想要类似( LINQPad c# 程序片段)的内容:

void Main()
{
    //can create user but not read the information back
    var userCanBeCreatedPermission = Permissions.Create | Permissions.User;

    //can create and readback
    var userCanBeCreatedAndReadBackPermission = userCanBeCreatedPermission | Permissions.Read;

    userCanBeCreatedPermission.HasFlag(Permissions.User).Dump(); //returns true

    (userCanBeCreatedPermission.HasFlag(Permissions.User) && userCanBeCreatedPermission.HasFlag(Permissions.Read)).Dump(); //returns false

    //alternative way of checking flags is to combine the flags and do an And mask check
    //the above can be written as
    ((userCanBeCreatedPermission & (Permissions.User | Permissions.Read)) == (Permissions.User | Permissions.Read)).Dump(); //returns false

    //using a variable to have combined permissions for readibility & using And mask:
    var desiredPermissions = Permissions.User | Permissions.Read;

    //checking with user that has both Create & Read permissions

    ((userCanBeCreatedAndReadBackPermission & desiredPermissions) == desiredPermissions).Dump(); // returns true because the user information can be read back by this user

    ((userCanBeCreatedAndReadBackPermission & Permissions.Delete) == Permissions.Delete).Dump(); // returns false because the user can't be deleted
}

[Flags]
public enum Permissions
{
   None = 0,
   Create = 1 << 0,
   Read = 1 << 1,
   Update = 1 << 2,
   Delete = 1 << 3,

   User = 1 << 4,
   Group = 1 << 5
}

这是否回答了您的问题？