WebDataGrid DropDownList在回发中丢失状态

Question

我有TemplateDataField，其中包含DropDownList control in WebDataGrid。这个DropDownList绑定在WebDataGrid的行初始化事件中，每个回发网格都使用存储在视图状态中的DataTable再次绑定，但是复选框上的一点改变了从数据库获取的事件数据并绑定到网格，直到一切正常运行为止。但是当我单击按钮(从网格获取所有数据并将其保存到数据库中的保存按钮)时，DropDownList中没有找到任何项，那么这其中有什么问题呢？

所有控件都在“更新”面板中。

Answer 1

我有两个建议:在ItemTemplate创建时绑定列表，而不是RowInitialize服务器事件；如果要动态创建模板，则使用Page_Init。

代码片段：

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Init(object sender, EventArgs e)
    {
        TemplateDataField FreightField = new TemplateDataField();
        FreightField.ItemTemplate = new CustomTemplate();
        FreightField.VisibleIndex = 2;
        FreightField.Key = "Freight";

        TemplateDataField ShippedDateField = new TemplateDataField();
        ShippedDateField.ItemTemplate = new CustomTemplate2();
        ShippedDateField.VisibleIndex = 3;
        ShippedDateField.Key = "ShippedDate";

        if (this.WebDataGrid1.Columns.FromKey("Freight") != null)
        {
            ((TemplateDataField)this.WebDataGrid1.Columns["Freight"]).ItemTemplate = new CustomTemplate();
            ((TemplateDataField)this.WebDataGrid1.Columns["ShippedDate"]).ItemTemplate = new CustomTemplate2();

        }
        else
        {
            this.WebDataGrid1.Columns.Add(FreightField);
            this.WebDataGrid1.Columns.Add(ShippedDateField);
        }
    }

    protected void Page_Load(object sender, EventArgs e)
    {

    }
}

public class CustomTemplate : ITemplate
{
    public void InstantiateIn(Control container)
    {
        WebDropDown wdd = new WebDropDown();
        wdd.ID = "WebDropDown1";
        wdd.Width = Unit.Pixel(200);
        wdd.Items.Add(new DropDownItem("1", "1"));
        wdd.Items.Add(new DropDownItem("2", "2"));
        wdd.Items.Add(new DropDownItem("3", "3"));

        wdd.ClientEvents.SelectionChanged = "ctl00_WebDropDown1_SelectionChanged";

        container.Controls.Add(wdd);
    }

    protected void btn_Click(object sender, EventArgs e)
    {
        var temp = 0;
    }
}

public class CustomTemplate2 : ITemplate
{
    public void InstantiateIn(Control container)
    {
        WebDropDown wdd = new WebDropDown();
        wdd.ID = "WebDropDown2";
        wdd.Width = Unit.Pixel(200);
        wdd.Items.Add(new DropDownItem("4", "4"));
        wdd.Items.Add(new DropDownItem("5", "5"));
        wdd.Items.Add(new DropDownItem("6", "6"));


        container.Controls.Add(wdd);
    }
}