EF 6工作单元存储库:一个实体对象不能被多个IEntityChangeTracker实例引用

Question

我正在使用工作单元存储库模式，使用Unity Dependacy Inhejection将DataContext注入Repo的

我不断得到一个entity对象不能被多个IEntityChangeTracker实例引用。当我使用其他存储库来查找对象中的外键时，

例如，我的风险对象有一个RiskType，如果我设置RiskTypeId = 1，对象保存，如果我设置RiskTypeId = 1；RiskType = RiskTypeRepo.GetById(1)；然后我得到一个实体对象不能被IEntityChangeTracker的多个实例引用

下面是我注册DI的过程

     public static void RegisterComponents()
        {
          UnityContainer container = new Unity.UnityContainer();
          container.EnableDiagnostic();
    
          var context = new EveModel();
    container.RegisterType<IRiskRepository, RiskRepo>(new InjectionConstructor(context));
          container.RegisterType<IRiskService, RiskService>();
        
          //GlobalConfiguration.Configuration.DependencyResolver = new UnityDependencyResolver( container);
          GlobalConfiguration.Configuration.DependencyResolver = new Unity.WebApi.UnityDependencyResolver(container);
        }





//here is the repo constructor and Save method



    public abstract class Repository<TEntity> : IRepositoryBase<TEntity> where TEntity : AbstractBase, 
          new()
        public Repository(EveModel injectedContext)
                {
                    _context = injectedContext;
                    this.currentTime = DateTime.Now;
                        System.Data.Entity.SqlServer.SqlProviderServices.UseScopeIdentity = false;
                }

public async Task<TEntity> SaveAsync(TEntity obj)
        {
 
            try
            {
                //_context.Configuration.AutoDetectChangesEnabled = false;
                TEntity exist = await _context.Set<TEntity>().FindAsync(obj.Id);
                if (exist != null)
                {
                    _context.Entry(exist).CurrentValues.SetValues(obj);
                    await _context.SaveChangesAsync();
                }
                else
                {
                    ///_context.Entry(obj).State = EntityState.Added;
                    _context.Set<TEntity>().Attach(obj);
             


                    await _context.SaveChangesAsync();
                    _context.Entry(obj).Reload();
                    exist = await _context.Set<TEntity>().FindAsync(obj.Id);

                }

                return exist;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

}

Answer 1

为了确保您共享相同的db上下文实例(以避免此异常)，请将您的db上下文也添加到容器中。

UnityContainer container = new UnityContainer();
container.EnableDiagnostic();

container.RegisterType<EveModel>();
container.RegisterType<IRiskRepository, RiskRepo>(); // no need in InjectionConstructor parameter as Unity will resolve eveModel instance automatically