使用MySQL，实体框架+ Ext.NET更新记录

Question

I have a snippet of code that I can't quite get to work:

StoreDataHandler dataHandler = new StoreDataHandler(HttpContext.Request["data"]);
ChangeRecords<ChequeDiary> data = dataHandler.ObjectData<ChequeDiary>();

foreach (ChequeDiary item in data.Updated) {
    db.ChequeDiaries.Attach(item);
    db.Refresh(System.Data.Objects.RefreshMode.ClientWins, item);
}

This is meant to get the changes and update the underlying object but when I call

db.SaveChanges();

.. nothing is updated. If I use:

foreach (ChequeDiary item in data.Updated) {
    ChequeDiary obj = db.ChequeDiaries.FirstOrDefault(o => o.Id == item.Id);
    obj.BankedAmount = item.BankedAmount;
}

and explicity set each property, it works. Why?!

Answer 1

Your first example likely doesn't mark any properties as modified. Check the ObjectStateManager to confirm this. In general, you must modify properties after you attach the object.