c# - RadComboBox 选中的值为空

Question

当我点击我的按钮时，我得到了 SelectedValue = ""。

我的aspx:

<telerik:RadComboBox ID="ddl_contactList" runat="server" AutoPostBack="True" CausesValidation="False"
            CollapseDelay="0" Culture="ar-EG" ExpandDelay="0" Filter="StartsWith" ItemsPerRequest="10"
            MarkFirstMatch="true" Skin="Outlook" EnableAutomaticLoadOnDemand="True" EmptyMessage="-New Menu-"
            ShowMoreResultsBox="True" OnSelectedIndexChanged="ddl_contactList_SelectedIndexChanged"
            EnableItemCaching="false" EnableLoadOnDemand="True" EnableVirtualScrolling="True">
        </telerik:RadComboBox>

---

我的.cs:

 private void BindContactLists(int year, int main_code)
        {
            ddl_contactList.Items.Clear();
            DataTable dt = ContactList.GetContactListsByDep(year, main_code);
            ddl_contactList.DataSource = dt;
            ddl_contactList.DataTextField = "list_desc";
            ddl_contactList.DataValueField = "list_code";
            ddl_contactList.DataBind();

        }

---

我在 page load 中调用它，因为当我在!Page.Ispostback，我收到以下错误:

There is no assigned data source. Unable to complete callback request.

我该如何解决这个问题？现在:

ddl_contactList.Text == "MySelectedItemText"

但是

selectedValue == "" 和 selectedItem == ""

Answer 1

将对 BindContactLists() 的调用从 Page_Load() 方法转移到 Page_Init() 方法。这允许在页面生命周期的后期为 ViewState 绑定(bind)设置控件，并允许正确填充 SelectedValue 属性。