ASP.NET/DataList 的 DataItem 回发后为空

Question

在我的 ASP.NET 表单中回发(单击按钮)后，表单的所有 DataItem 均为空。为什么？即使在回发后，我应该怎么做才能检索 DataList 的内容？

protected void buttonAddRecord_Click(object sender, EventArgs e)
    {
        foreach (DataListItem item in listFields.Items)
        {
            // item.DataItem == null  WTF?
        }
    }

protected void Page_Load(object sender, EventArgs e)
    {
        BindFields();
    }

private void BindFields()
    {
        object setting = MySettings.GetSetting();

        if (!Null.IsNull(setting))
        {
            listFields.DataSource =     
                DataProvider.GetData(int.Parse(setting.ToString()));
            listFields.DataBind();
        }

        listFields.Visible = listFields.Items.Count > 0;
        emptyMessage.Visible = listFields.Items.Count == 0;
    }

Answer 1

找到我的答案 here .

What John said, the data source items are only avaliable when databound. They are no longer accessable after initial loading.

You might consider having an object or object collection representing onscreen data that you update with the grid, then persist changes from that to databases.

更准确地说，我使用 HiddenField 跨帖子存储 ID，并从数据库请求数据，而不是尝试从 DataItem 获取数据(不能在数据绑定(bind)事件之外使用)。

The HiddenField control is used to store a value that needs to be persisted across posts to the server.