在asp.net核心中插入/更新记录时出错

首先,很多人错过了这些检查,从而导致运行时异常。 因此,您应该始终检查实体的状态:

context.YourEntities.Local.Any(e => e.Id == id);

context.ChangeTracker.Entries<YourEntity>().Any(e => e.Entity.Id == id);

以确保您的实体 '安全使用' ,如果您想使用方便的方法,可以使用以下方法:

/// <summary>
    /// Determines whether the specified entity key is attached is attached.
    /// </summary>
    /// <param name="context">The context.</param>
    /// <param name="key">The key.</param>
    /// <returns>
    ///   <c>true</c> if the specified context is attached; otherwise, <c>false</c>.
    /// </returns>
    internal static bool IsAttached(this ObjectContext context, EntityKey key)
    {
        if (key == null)
        {
            throw new ArgumentNullException("key");
        }

        ObjectStateEntry entry;
        if (context.ObjectStateManager.TryGetObjectStateEntry(key, out entry))
        {
            return (entry.State != EntityState.Detached);
        }
        return false;
    }

然后 :

if (!_objectContext.IsAttached(entity.EntityKey))
{
   _objectContext.Attach(entity);
}

SaveChanges() 方法,这在任何情况下都是不推荐的,除非你真的必须这样做。

如果你想和我一起吃饭的话 Primary-Key 还有 Identity-Incremental 你必须创造你的 Table 凝固后 ForeignKey 你必须把 为了这个 . 比如:

对于此问题,您的代码将更改为:

    public bool SaveDataCapDetails(List<TDataCapDetails> lstDataCapDetails)
    {
        bool IsSuccess = false;

        using (var dbContextTransaction = _objContext.Database.BeginTransaction())
        {
            try
            {

                List<TDataCapDetails> lstDataCapDetailsRecords = null;

                if (lstDataCapDetails.Where(x => x.Id == 0).Count() > 0)
                {
                    lstDataCapDetailsRecords = new List<TDataCapDetails>();
                    _objContext.AddRange(lstDataCapDetailsRecords);
                    _objContext.SaveChanges();
                }

                if (lstDataCapDetails.Where(x => x.Id > 0).Count() > 0)
                {
                    lstDataCapDetailsRecords = new List<TDataCapDetails>();
                    lstDataCapDetailsRecords = lstDataCapDetails.Where(x => x.Id > 0).ToList();
                    _objContext.UpdateRange(lstDataCapDetailsRecords);
                    _objContext.SaveChanges();
                }

                dbContextTransaction.Commit();
            }
            catch (Exception ex)
            {
                dbContextTransaction.Rollback();
                throw ex;
            }
        }

        return IsSuccess;
    }

我看到您对Add和Update实体使用相同的方法,我的第一个建议是分离关注点,并使不同的方法一个用于Add,另一个用于Update(如果可能的话)。

另一方面,不清楚记录列表“lstDataCapDetails”是否包含要更新的所有新记录或新记录与现有记录的混合,在第二种情况下,您的代码将给您带来错误,因为您可能尝试为现有记录分配Id,或者您可能尝试更新全新的记录。

您可以在此处看到方法的修改版本:

public bool SaveDataCapDetails(List<TDataCapDetails> lstDataCapDetails)
    {
        bool IsSuccess = false;

        using (var dbContextTransaction = _objContext.Database.BeginTransaction())
        {
            try
            {
                int? id = _objContext.TDataCapDetails.Max(x => (int?)x.Id);
                id = id == null ? 0 : id;

                // entities with Id == 0 --> new entities
                // you may need to check if Id == null as well (depends on your data model)
                var entitiesToAdd = lstDataCapDetails.Where(x => x.Id == 0);
                foreach(var entity in entitiesToAdd)
                {
                    entity.Id = id++;

                    // new entities is not tracked, its state can be changed to Added
                    _objContext.Entry(entity).State = EntityState.Added;
                }

                // entities with Id > 0 is already exists in db and needs to be updated
                var entitiesToUpdate = lstDataCapDetails.Where(x => x.Id > 0);
                foreach (var entity in entitiesToUpdate)
                {
                    // check if entity is being tracked
                    var local = _objContext.Set<TDataCapDetails>().Local.FirstOrDefault(x => x.Id.Equals(entity.Id));

                    // if entity is tracked detach it from context
                    if (local != null)
                        _objContext.Entry<TDataCapDetails>(local).State = EntityState.Detached;

                    // attach modified entity and change its state to modified
                    _objContext.Attach(entity).State = EntityState.Modified;
                }

                // optional: assign value for IsSuccess
                IsSuccess = _objContext.SaveChanges() > 0;                    

                dbContextTransaction.Commit();
            }
            catch (Exception ex)
            {
                dbContextTransaction.Rollback();
                throw ex;
            }
        }

        return IsSuccess;
    }

model ,而不是真正保持一个未追踪的 在里面 memory . 我有一个小建议或实际上是一个替代的建议方法,可以解决你的问题。

EntityFramework 将自动跟踪更改。但你可以 Ovverride SaveChanges() 在你的 DbContext .

public override int SaveChanges()
{
    foreach (var ent in ChangeTracker.Entries<Client>())
    {
        if (ent.State == EntityState.Modified)
        {
            // Get the changed values
            var modifiedProps = ObjectStateManager.GetObjectStateEntry(ent.EntityKey).GetModifiedProperties();
            var currentValues = ObjectStateManager.GetObjectStateEntry(ent.EntityKey).CurrentValues;
            foreach (var propName in modifiedProps)
            {
                var newValue = currentValues[propName];
                //log your changes
            }
        }
    }

    return base.SaveChanges();
}