在DbContext中访问HttpContext.Current.User.Identity.Name

Question

我将使用UserName来跟踪“创建”和“修改”字段。为此，我直接在DbContext中引用了System.Web程序集：

public void auditFields()
 {
            var auditDate = DateTime.Now;
            foreach (var entry in this.ChangeTracker.Entries<BaseEntity>())
            {
                switch (entry.State)
                {
                    case EntityState.Detached:
                        break;
                    case EntityState.Unchanged:
                        break;
                    case EntityState.Added:
                        entry.Entity.CreatedOn = auditDate;
                        entry.Entity.ModifiedOn = auditDate;
                        entry.Entity.CreatedBy = HttpContext.Current.User.Identity.Name ?? "anonymouse";
                        entry.Entity.ModifiedBy = HttpContext.Current.User.Identity.Name ?? "anonymouse";
                        break;
                    case EntityState.Deleted:
                        break;
                    case EntityState.Modified:
                        entry.Entity.ModifiedOn = auditDate;
                        entry.Entity.ModifiedBy = HttpContext.Current.User.Identity.Name ?? "anonymouse";
                        break;
                    default:
                        throw new ArgumentOutOfRangeException();
                }
            }
}

它可以正常工作，但是将DbContext与HttpContext紧密结合在一起，如果我们将DbContext暴露在非Web环境中，这不是一个好主意。所以我用这种方式：

public class ApplicationDbContext :
        IdentityDbContext<ApplicationUser, CustomRole, int, CustomUserLogin, CustomUserRole, CustomUserClaim>,
        IUnitOfWork
{
    public ApplicationDbContext()
            : base("ConnectionString")
        {
        }
        public ApplicationDbContext(string userName)
            : base("ConnectionString")
        {
            UserName = userName;
        }
    //Other codes
    public string UserName
        {
            get;
            private set;
        }
    public void auditFields()
    {
            var auditDate = DateTime.Now;
            foreach (var entry in this.ChangeTracker.Entries<BaseEntity>())
            {
                switch (entry.State)
                {
                    case EntityState.Detached:
                        break;
                    case EntityState.Unchanged:
                        break;
                    case EntityState.Added:
                        entry.Entity.CreatedOn = auditDate;
                        entry.Entity.ModifiedOn = auditDate;
                        entry.Entity.CreatedBy = UserName ?? "anonymouse";
                        entry.Entity.ModifiedBy = UserName ?? "anonymouse";
                        break;
                    case EntityState.Deleted:
                        break;
                    case EntityState.Modified:
                        entry.Entity.ModifiedOn = auditDate;
                        entry.Entity.ModifiedBy = UserName ?? "anonymouse";
                        break;
                    default:
                        throw new ArgumentOutOfRangeException();
                }
            }
    }
}

在Ioc配置项目中（我在另一个类库中使用structureMap）：

ioc.For<IUnitOfWork>()
                   .HybridHttpOrThreadLocalScoped()
                   .Use<ApplicationDbContext>()
                   .Ctor<string>().Is(HttpContext.Current.User.Identity.Name);

但是，当我运行应用程序时，我会在上一行得到此错误：

Object reference not set to an instance of an object

似乎无法注入HttpContext。

任何的想法？

Answer 1

看看这个链接http://techbrij.com/service-layer-entity-framework-asp-net-mvc-unit-testing

作者的解决方案看起来像你的（但他使用 AutoFac 而不是 StructureMap）。他获得“名字”的“伎俩”是Thread.CurrentPrincipal.Identity.Name;

另一件事，恕我直言，我认为你应该使用DateTimeOffSet而不是DateTime审计日期。使用DateTimeOffSet你不会有不同时区的问题。像这样：

DateTimeOffSet auditDate = DateTime.UtcNow;