Listing 14-6. The Contents of the AppRole.cs File
清单14-6. AppRole文件的内容

using Microsoft.AspNet.Identity.EntityFramework;
namespace Users.Models { public class AppRole : IdentityRole {
public AppRole() : base() {}
public AppRole(string name) : base(name) { } } }

The RoleManager<T> class operates on instances of the IRole implementation class through the methods and properties shown in Table 14-8.
RoleManager<T> 类通过表14-8所示的方法和属性对IRole实现类的实例进行操作。

Table 14-8. The Members Defined by the RoleManager<T> Class
表14-8. RoleManager<T>类定义的成员

Name
名称 Description
描述

CreateAsync(role) Creates a new role
创建一个新角色

DeleteAsync(role) Deletes the specified role
删除指定角色

FindByIdAsync(id) Finds a role by its ID
找到指定ID的角色

FindByNameAsync(name) Finds a role by its name
找到指定名称的角色

RoleExistsAsync(name) Returns true if a role with the specified name exists
如果存在指定名称的角色，返回true

UpdateAsync(role) Stores changes to the specified role
将修改存储到指定角色

Roles Returns an enumeration of the roles that have been defined
返回已被定义的角色枚举

These methods follow the same basic pattern of theUserManager<T> class that I described in Chapter 13. Following the pattern I used for managing users, I added a class file called AppRoleManager.cs to the Infrastructure folder and used it to define the class shown in Listing 14-7.
这些方法与第13章描述的UserManager<T> 类有同样的基本模式。按照对管理用户所采用的模式，我在Infrastructure文件夹中添加了一个类文件，名称为AppRoleManager.cs，用它定义了如清单14-7所示的类。

Listing 14-7. The Contents of the AppRoleManager.cs File
清单14-7. AppRoleManager.cs文件的内容

using System; using Microsoft.AspNet.Identity; using Microsoft.AspNet.Identity.EntityFramework; using Microsoft.AspNet.Identity.Owin; using Microsoft.Owin; using Users.Models;
namespace Users.Infrastructure {
public class AppRoleManager : RoleManager<AppRole>, IDisposable {
public AppRoleManager(RoleStore<AppRole> store) : base(store) { }
public static AppRoleManager Create( IdentityFactoryOptions<AppRoleManager> options, IOwinContext context) { return new AppRoleManager(new RoleStore<AppRole>(context.Get<AppIdentityDbContext>())); } } }

This class defines a Create method that will allow the OWIN start class to create instances for each request where Identity data is accessed, which means I don’t have to disseminate details of how role data is stored throughout the application. I can just obtain and operate on instances of the AppRoleManager class. You can see how I have registered the role manager class with the OWIN start class, IdentityConfig, in Listing 14-8. This ensures that instances of the AppRoleManager class are created using the same Entity Framework database context that is used for the AppUserManager class.
这个类定义了一个Create方法，它让OWIN启动类能够为每一个访问Identity数据的请求创建实例，这意味着在整个应用程序中，我不必散布如何存储角色数据的细节，却能获取AppRoleManager类的实例，并对其进行操作。在清单14-8中可以看到如何用OWIN启动类（IdentityConfig）来注册角色管理器类。这样能够确保，可以使用与AppUserManager类所用的同一个Entity Framework数据库上下文，来创建AppRoleManager类的实例。

Listing 14-8. Creating Instances of the AppRoleManager Class in the IdentityConfig.cs File
清单14-8. 在IdentityConfig.cs文件中创建AppRoleManager类的实例

using Microsoft.AspNet.Identity; using Microsoft.Owin; using Microsoft.Owin.Security.Cookies; using Owin; using Users.Infrastructure;
namespace Users { public class IdentityConfig { public void Configuration(IAppBuilder app) {
app.CreatePerOwinContext<AppIdentityDbContext>(AppIdentityDbContext.Create); app.CreatePerOwinContext<AppUserManager>(AppUserManager.Create); app.CreatePerOwinContext<AppRoleManager>(AppRoleManager.Create); app.UseCookieAuthentication(new CookieAuthenticationOptions { AuthenticationType = DefaultAuthenticationTypes.ApplicationCookie, LoginPath = new PathString("/Account/Login"), }); } } }

14.3.2 Creating and Deleting Roles
14.3.2 创建和删除角色

Having prepared the application for working with roles, I am going to create an administration tool for managing them. I will start the basics and define action methods and views that allow roles to be created and deleted. I added a controller called RoleAdmin to the project, which you can see in Listing 14-9.
现在已经做好了应用程序使用角色的准备，我打算创建一个管理工具来管理角色。首先从基本的开始，定义能够创建和删除角色的动作方法和视图。我在项目中添加了一个控制器，名称为RoleAdmin，如清单14-9所示。