御用小本本

結論

• SaveChangesAsync()
  • 只會更新實體部分有變更的欄位
• UpdateAsync(TEntity)
  • 會更新整個實體全部欄位
  • 當取得實體與更新實體之間，有其他東西改了其他欄位，會造成資料被複寫回舊的資料
    • A程序取得B欄位=C,D欄位=E
    • F程序更新D欄位=G
    • A程序改變B欄位=H, 並使用 UpdateAsync 更新實體, D會一併被更新成E
    • 預期 B=C, D=G, 實際會變成 B=C, D=E

範例程式碼

var e = await _repository.FirstOrDefaultAsync();

e.OrderNumber = DateTime.Now.ToString("yyyyMMddHHmmss");
await _repository.UpdateAsync(e);
await CurrentUnitOfWork.SaveChangesAsync();


e.OrderNumber = DateTime.Now.ToString("yyMMddHHmmss");
await CurrentUnitOfWork.SaveChangesAsync();

紀錄

UPDATE [AppOrders] SET [ConcurrencyStamp] = @p0, [CreationTime] = @p1, [CreatorId] = @p2, [DeleterId] = @p3, [DeletionTime] = @p4, [ExtraProperties] = @p5, [IsDeleted] = @p6, [LastModificationTime] = @p7, [LastModifierId] = @p8,
[OrderDate] = @p9, [OrderNumber] = @p10, [PartnerId] = @p11, [Status] = @p12
WHERE [Id] = @p13 AND [ConcurrencyStamp] = @p14;

UPDATE [AppOrders] SET [ConcurrencyStamp] = @p0, [LastModificationTime] = @p1, [OrderNumber] = @p2
WHERE [Id] = @p3 AND [ConcurrencyStamp] = @p4;
SELECT @@ROWCOUNT;

補充

當 entity 有某欄位是自動增量，

entity.Property(e => e.AutoId).ValueGeneratedOnAdd();

使用 UpdateAsync 會拋出例外

Cannot update identity column 'AutoId'.

請改用 SaveChangesAsync