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

Question

我将使用 UserName 来跟踪 Created 和 Modified 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();
                }
            }
}

它可以工作，但它会将 DbContext 与 HttpContext 紧密耦合，这不是一个好主意，以防我们将 DbContext 暴露给非 Web 环境。所以我这样使用：

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();
                }
            }
    }
}

并且在 Ioc 配置项目中（我在另一个 class 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，我会在上面的行中得到这个错误：

Object reference not set to an instance of an object

好像不能注入HttpContext

有什么想法吗？

Answer 1

看看这个linkhttp://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 "Name" 的 "trick" 是 Thread.CurrentPrincipal.Identity.Name;

另一件事，恕我直言，我认为您应该使用 DateTimeOffSet 而不是 DateTime 作为审计日期。使用 DateTimeOffSet 您不会遇到不同时区的问题。像这样：

DateTimeOffSet auditDate = DateTime.UtcNow;

Answer 2

以下应该有所帮助

http://mikehadlow.blogspot.com/2008/08/taking-httpcontext-out-of-mvc-framework.html

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

Accessing HttpContext.Current.User.Identity.Name in the DbContext

c#

entity-framework

dbcontext

structuremap3