ABP框架使用(版本3.3.1)

    public class Test : FullAuditedAggregateRootWithUser<Guid, AppUser>
    {
        public string TransactionNumber { get; set; }

        public virtual List<TestItem> TestItems { get; set; }
    }
    
    public class TestItem : AuditedEntity
    {
        public Guid TestId { get; set; }
        public Guid ItemId { get; set; }

        [ForeignKey("ItemId")]
        public Item Item { get; set; }
        public int Quantity { get; set; }

        public virtual List<TestSubItem> TestSubItems { get; set; }
        public override object[] GetKeys()
        {
            return new object[] { TestId,ItemId };
        }
    }
    
        public class TestSubItem : AuditedEntity
    {
        public Guid TestId { get; set; }
        public Guid ItemId { get; set; }

        [ForeignKey("TierId")]
        public Tier Tier { get; set; }
        public Guid TierId { get; set; }
        public int Quantity { get; set; }
        public override object[] GetKeys()
        {
            return new object[] { TestId, ItemId , TierId };
        }
    }

1.当update TestItem的值 ， 使用updateaync会报错

2021-03-27 18:51:43.422 +08:00 [ERR] The instance of entity type 'TestSubItem' cannot be tracked because another instance with the same key value for {'TestId', 'ItemId', 'SubItemId'} is already being tracked. When attaching existing entities, ensure that only one entity instance with a given key value is attached. Consider using 'DbContextOptionsBuilder.EnableSensitiveDataLogging' to see the conflicting key values.

研究了好久，找不到方法override 这个类 StateManager.

用下面改变 EntityState 的方法是有时凑效有时不凑效

_context.Attach(modelPostedToController);
IEnumerable<EntityEntry> unchangedEntities = _context.ChangeTracker.Entries().Where(x => x.State == EntityState.Unchanged);
foreach(EntityEntry ee in unchangedEntities){
     ee.State = EntityState.Modified;
}
await _context.SaveChangesAsync();

最后的解决方案是先 remove 再 update, 而且一定不能用 DbContext.SaveChangesAsync()

要是用aynchu会报错

[ERR] A second operation started on this context before a previous operation completed. This is usually caused by different threads using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.

    public class TestItemRepository : EfCoreRepository<DRSDbContext, TestItem>, ITestItemRepository
    {

        public TestItemRepository(IDbContextProvider<DRSDbContext> dbContextProvider) : base(dbContextProvider)
        {

        }

        public Task Save(List<TestItem> entities)
        {
            DbContext.AttachRange(entities);
            DbContext.UpdateRange(entities);
            DbContext.SaveChanges();
            return Task.CompletedTask;
        }

        public Task Remove(List<TestItem> entities)
        {
            DbContext.AttachRange(entities);
            DbContext.RemoveRange(entities);
            DbContext.SaveChanges();
            return Task.CompletedTask;
        }

    }

2.当update sub entity的时候，如果sub entity有soft delete的话就会报duplicate key错。

sub entity不可以有soft delete，才可以update成功。当做法总是会先删除旧的那条，再新增新的那条。所以从last modify time时间来看是不能正确反映真实情况的。

在abp没有找到DbContext如何触发到ChangeTracker的代码，翻看了下ef core的源代码，用的ReferenceEquals，无从改造大。

那么就还是在DbContext对ChangeTracker再做一层过滤，回归到Unchanged和Modified的State.

DbContext

  protected override EntityChangeReport ApplyAbpConcepts()    
 {
            var changeReport = new EntityChangeReport();
            var addList = ChangeTracker.Entries().Where(o => o.State == EntityState.Added).ToList();
            var delList = ChangeTracker.Entries().Where(o => o.State == EntityState.Deleted).ToList();
            var addListKeys = addList.Select(o => GetEntityId(o.Entity)).ToList();
            var delListKeys = delList.Select(o => GetEntityId(o.Entity)).ToList();
            var addListHashCodes = addList.Select(o => o.Entity.GetHashCode()).ToList();
            var delListHashCodes = delList.Select(o => o.Entity.GetHashCode()).ToList();
            var modListKeys = addListKeys.Intersect(delListKeys);
            var modListHashCodes = addListHashCodes.Intersect(delListHashCodes);

        
            foreach (var entry in ChangeTracker.Entries().ToList())
            {
                var keys = GetEntityId(entry.Entity);
                var hashCodes = entry.Entity.GetHashCode();
                if (entry.State == EntityState.Added && modListHashCodes.Contains(hashCodes))
                {
                    entry.State = EntityState.Unchanged;
                }
                else if (entry.State == EntityState.Added && modListKeys.Contains(keys))
                {
                    entry.State = EntityState.Modified;
                }
                if (entry.State == EntityState.Deleted && modListKeys.Contains(keys))
                    continue;
                ApplyAbpConcepts(entry, changeReport);
            }

            return changeReport;
        }

这里因为Added entity 的LastModifyTime和Deleted entity 的LastModifyTime不一致，所以要改写sub entity的GetHashCode() 方法，才能判断出两者是UnChanged

    public class ItemTier : AuditedEntity //FullAuditedEntity
    {
        public Guid ItemId { get; set; }
        
        public Guid TierId { get; set; }

        [ForeignKey("ItemId")]
        public virtual Item Item { get; set; }

        [ForeignKey("TierId")]
        public /*virtual*/  Tier Tier { get; set; }

        public bool Allow { get; set; }

        public override object[] GetKeys()
        {
            return new object[] { ItemId, TierId };
        }

        public override int GetHashCode()
        {
            unchecked // Overflow is fine, just wrap
            {
                int hash = 17;
                // Suitable nullity checks etc, of course :)
                hash = hash * 23 + ItemId.GetHashCode();
                hash = hash * 23 + TierId.GetHashCode();
                hash = hash * 23 + Allow.GetHashCode();
                return hash;
            }
        }

    }