(EF4.1 - 4.0框架)
网络上的大部分代码示例都规定了Entity Framework的最佳实践;它们说要在using块中包装DBContext的使用,以确保无状态操作。即使如此,我仍然遇到了似乎是共享缓存错误的问题。
错误:
对象StateManager中已经存在具有相同键的对象。 ObjectStateManager无法跟踪具有相同键的多个对象。
查看了一下,发现这种情况的示例是当某人在多个调用之间共享全局DBContext实例时发生的。
然而,我在一个静态数据访问层服务类中的以下函数的第二次调用中收到了这个错误信息。
public static void UpdateRollout(Rollout rollout)
{
using (ITAMEFContext db = new ITAMEFContext(ConnectionStrings.XYZConnectionString))
{
db.Configuration.ProxyCreationEnabled = false;
db.Configuration.LazyLoadingEnabled = false;
FixUp(rollout);
db.Rollouts.Attach(rollout);
db.Entry(rollout).State = System.Data.EntityState.Modified;
db.SaveChanges();
//db.Entry(rollout).State = System.Data.EntityState.Detached;
}
}
private static void FixUp(Rollout rollout)
{
// ensure manual fixup of foreign keys
if (rollout.RolloutState != null)
rollout.FK_RolloutState_ID = rollout.RolloutState.ID;
if (rollout.Lead != null)
rollout.RolloutLead_FK_User_ID = rollout.Lead.ID;
}
EFContext是通过EF 4.x DBContext Fluent Generator生成的,该生成器引用了一个edmx模型。
![edmx模型图片](https://istack.dev59.com/klP2h.webp)
public partial class ITAMEFContext : DbContext
{
static ITAMEFContext()
{
Database.SetInitializer<ITAMEFContext>(null);
}
public ITAMEFContext() : base("name=ITAMEFContext")
{
this.Configuration.LazyLoadingEnabled = false;
}
public ITAMEFContext(string nameOrConnectionString) : base(nameOrConnectionString)
{
}
public ITAMEFContext(string nameOrConnectionString, DbCompiledModel model) : base(nameOrConnectionString, model)
{
}
public ITAMEFContext(DbConnection existingConnection, bool contextOwnsConnection) : base(existingConnection, contextOwnsConnection)
{
}
public ITAMEFContext(DbConnection existingConnection, DbCompiledModel model, bool contextOwnsConnection) : base(existingConnection, model, contextOwnsConnection)
{
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Conventions.Remove<IncludeMetadataConvention>();
modelBuilder.Configurations.Add(new Asset_Mapping());
modelBuilder.Configurations.Add(new AssetAllocation_Mapping());
modelBuilder.Configurations.Add(new AssetAssignee_Mapping());
modelBuilder.Configurations.Add(new AssetAssigneeType_Mapping());
modelBuilder.Configurations.Add(new AssetDeAllocation_Mapping());
modelBuilder.Configurations.Add(new AssetState_Mapping());
modelBuilder.Configurations.Add(new AssetType_Mapping());
modelBuilder.Configurations.Add(new Department_Mapping());
modelBuilder.Configurations.Add(new Location_Mapping());
modelBuilder.Configurations.Add(new ManagementGroup_Mapping());
modelBuilder.Configurations.Add(new Role_Mapping());
modelBuilder.Configurations.Add(new Rollout_Mapping());
modelBuilder.Configurations.Add(new RolloutState_Mapping());
modelBuilder.Configurations.Add(new ServiceArea_Mapping());
modelBuilder.Configurations.Add(new Software_Mapping());
modelBuilder.Configurations.Add(new SoftwareType_Mapping());
modelBuilder.Configurations.Add(new SubTeam_Mapping());
modelBuilder.Configurations.Add(new sys_UserLock_Mapping());
modelBuilder.Configurations.Add(new Team_Mapping());
modelBuilder.Configurations.Add(new User_Mapping());
modelBuilder.Configurations.Add(new WorkingMethod_Mapping());
}
public DbSet<Asset> Assets { get; set; }
public DbSet<AssetAllocation> AssetAllocations { get; set; }
public DbSet<AssetAssignee> AssetAssignees { get; set; }
public DbSet<AssetAssigneeType> AssetAssigneeTypes { get; set; }
public DbSet<AssetDeAllocation> AssetDeAllocations { get; set; }
public DbSet<AssetState> AssetStates { get; set; }
public DbSet<AssetType> AssetTypes { get; set; }
public DbSet<Location> Locations { get; set; }
public DbSet<Department> Departments { get; set; }
public DbSet<ManagementGroup> ManagementGroup { get; set; }
public DbSet<Role> Roles { get; set; }
public DbSet<ServiceArea> ServiceAreas { get; set; }
public DbSet<SubTeam> SubTeams { get; set; }
public DbSet<Team> Teams { get; set; }
public DbSet<User> User { get; set; }
public DbSet<WorkingMethod> WorkingMethods { get; set; }
public DbSet<Rollout> Rollouts { get; set; }
public DbSet<RolloutState> RolloutStates { get; set; }
public DbSet<Software> Softwares { get; set; }
public DbSet<SoftwareType> SoftwareTypes { get; set; }
public DbSet<sys_UserLock> sys_UserLock { get; set; }
}
我希望能够在我的BL层中随时调用UpdateRollout。UI需要保持对先前获取的List返回的纯POCO Rollout实体图形的掌握。
Rollout和所有其他实体都是纯POCO,不需要上下文跟踪。
我读到过,任何上下文缓存/跟踪都会在using块销毁ITAMEFContext后被清除。然而,似乎有某种全局缓存作为同一应用程序域中任何DBContext实例的基础?老实说,到目前为止,EF似乎比使用好老式存储过程的分层应用程序更费力。
这是POCO。
public partial class Rollout
{
public Rollout()
{
this.AssetAssignees = new HashSet<AssetAssignee>();
}
public int ID { get; set; }
public string Name { get; set; }
public int RolloutLead_FK_User_ID { get; set; }
public string EmailContacts { get; set; }
public System.DateTime Schedule { get; set; }
public int FK_RolloutState_ID { get; set; }
public Nullable<int> NotificationDays { get; set; }
public string Notes { get; set; }
public virtual ICollection<AssetAssignee> AssetAssignees { get; set; }
public virtual User Lead { get; set; }
public virtual RolloutState RolloutState { get; set; }
}
编辑:
映射。
internal partial class Rollout_Mapping : EntityTypeConfiguration<Rollout>
{
public Rollout_Mapping()
{
this.HasKey(t => t.ID);
this.ToTable("Rollout");
this.Property(t => t.ID).HasColumnName("ID");
this.Property(t => t.Name).HasColumnName("Name").IsRequired().HasMaxLength(50);
this.Property(t => t.RolloutLead_FK_User_ID).HasColumnName("RolloutLead_FK_User_ID");
this.Property(t => t.EmailContacts).HasColumnName("EmailContacts").HasMaxLength(500);
this.Property(t => t.Schedule).HasColumnName("Schedule");
this.Property(t => t.FK_RolloutState_ID).HasColumnName("FK_RolloutState_ID");
this.Property(t => t.NotificationDays).HasColumnName("NotificationDays");
this.Property(t => t.Notes).HasColumnName("Notes");
this.HasRequired(t => t.Lead).WithMany(t => t.Rollouts).HasForeignKey(d => d.RolloutLead_FK_User_ID);
this.HasRequired(t => t.RolloutState).WithMany(t => t.Rollouts).HasForeignKey(d => d.FK_RolloutState_ID);
}
}
EntityState
之前,请检查rollout的状态。如果已附加,请先将其分离(如果将导航属性设置为已跟踪的实体,则新实体将自动添加)。 - VahidN