首先使用Entity Framework 4和代码如何创建支持此场景的模型:
在应用程序中,有用户,每个用户属于一个或更多组,每个用户可以拥有一个或更多角色。
示例:
我希望能够说“给我Lisa”,并且响应会返回lisa的用户对象,以及她所属的组。对于每个组,都有一个list属性,其中包含她对该特定组的所有角色
任何人都可以先帮助我使用代码对此进行建模,任何帮助/代码示例都会很棒!
/最好的问候Vinblad
答案 0 :(得分:2)
编辑:这是符合您要求的新型号。
public class User
{
public virtual int Id { get; set; }
public virtual ICollection<UserPermission> Permissions { get; set; }
}
// Permission is extended junction table to model M:N between
// User and Group but in addition it contains relation to Roles.
// The ony disadvantage is that this model doesn't control that
// role in the collection is also the role related to group. You
// must either enforce it in application logic or create some additional
// database construct to check it.
public class UserPermission
{
public virtual int UserId { get; set; }
public virtual int GroupId { get; set; }
public virtual Group Group { get; set; }
public virtual ICollection<Role> Roles { get; set; }
}
public class Group
{
public virtual int Id { get; set; }
public virtual ICollection<UserPermission> UserPermissions { get; set; }
public virtual ICollection<Role> Roles { get; set; }
}
public class Role
{
public virtual int Id { get; set; }
public virtual ICollection<Group> Groups { get; set; }
public virtual ICollection<UserPermission> UserPermissions { get; set; }
}
public class Context : DbContext
{
public DbSet<User> Users { get; set; }
public DbSet<Group> Groups { get; set; }
public DbSet<Role> Roles { get; set; }
public DbSet<UserPermission> UserPermissions { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
// Permission has composite key
modelBuilder.Entity<UserPermission>()
.HasKey(p => new {p.UserId, p.GroupId});
// Permission doesn't have navigation property to user
modelBuilder.Entity<User>()
.HasMany(u => u.Permissions)
.WithRequired()
.HasForeignKey(p => p.UserId);
modelBuilder.Entity<Group>()
.HasMany(g => g.UserPermissions)
.WithRequired(p => p.Group)
.HasForeignKey(p => p.GroupId);
}
}
如代码所述,存在一些小缺点。您可以通过额外的FK在DB中强制执行数据完整性来避免这种缺点,这些FK无法首先通过代码建模。您可以使用自定义初始值设定项添加该FK:
public class CustomInitializer : DropCreateDatabaseIfModelChanges<Context>
{
protected override void Seed(Context context)
{
context.Database.ExecuteSqlCommand(
@"ALTER TABLE [dbo].[RoleUserPermissions]
WITH CHECK ADD CONSTRAINT [FK_RoleUserPermissions_RoleGroups]
FOREIGN KEY([Role_Id], [UserPermission_GroupId])
REFERENCES [dbo].[RoleGroups] ([Role_Id], [Group_Id])");
}
}
只需将此添加到您的应用程序初始化(仅用于调试 - 应用程序不应该在发布时删除其数据库):
Database.SetInitializer(new CustomInitializer());