Dropdown "SelectedIndexChanged" 事件中的错误，同时从 RadComboBox 中选择新项目

Question

在我的网页中，RadGrid 外有一个 RadComboBox，RadGrid 内有一个 Dropdown。

Dropdown 中的数据根据 RadComboBox 项目选择进行绑定。
Ex: 如果从 RadComboBox 中选择了项目 "Company"，则 Dropdown 中的数据将与 "Company" 相关（即 Company1、Company2、company3 等）

HTML代码：

<telerik:RadComboBox ID="ddlCompany" runat="server" Height="200" Width="240"
          DropDownWidth="310" EmptyMessage="- Select Product -" HighlightTemplatedItems="true" CausesValidation="false" Filter="StartsWith" AppendDataBoundItems="true" AllowCustomText="true" AutoPostBack="true" DataTextField="Title" DataValueField="Code" OnSelectedIndexChanged="ddlCompany_SelectedIndexChanged">
</telerik:RadComboBox>

<telerik:RadGrid ID="RGGSTAcCode" runat="server">       
    <Columns> 
         <telerik:GridEditCommandColumn></telerik:GridEditCommandColumn> 

         <telerik:GridTemplateColumn UniqueName="AccountCode" HeaderText="Account Code">
             <ItemTemplate>
                 <asp:Label ID="lblAcCode" Text='<%# Eval("AccountCode") %>' runat="server"></asp:Label>
             </ItemTemplate>
             <EditItemTemplate>
                 <asp:DropDownList ID="ddlAcCode" DataTextField="AccountDescription" DataValueField="AccountCodeID" runat="server"/> 
             </EditItemTemplate>
         </telerik:GridTemplateColumn>
     </Columns>

C#代码：

public DataSet GetCompanyNames()
{
    SqlConnection con = new SqlConnection(strcon);
    SqlCommand cmd = new SqlCommand("General.usp_tbl_BuyerCode_Query", con);
    cmd.CommandType = CommandType.StoredProcedure;
    SqlDataAdapter da = new SqlDataAdapter(cmd);
    DataSet ds = new DataSet();
    try
    {
        con.Open();
        da.Fill(ds);
        con.Close();
    }
    catch (Exception ex)
    {
    }
    return ds;
}

protected void BindComapnyDL()
{
    ddlCompany.DataTextField = "Title";
    ddlCompany.DataValueField = "Code";
    ddlCompany.DataSource = GetCompanyNames();
    ddlCompany.DataBind();

    Session["Comp"] = ddlCompany.SelectedValue.ToString();
}

protected void ddlCompany_SelectedIndexChanged(object sender, RadComboBoxSelectedIndexChangedEventArgs e)
{
    if (ddlCompany.SelectedItem != null)
    {
        SqlConnection con = new SqlConnection(strcon);
        SqlDataAdapter adapter = new SqlDataAdapter();

        adapter.SelectCommand = new SqlCommand("SELECT [AccountCodeID],[AccountCode]+' - '+[AccountDescription] as[AccountDescription] FROM [Sunway_AP].[General].[tbl_AccountCode] (NOLOCK) Where [CompanyCode] = '" + Session["Comp"] + "' order by [AccountCode]+' - '+[AccountDescription]", con);
        con.Open();
        DataTable dt = new DataTable();
        try
        {
            adapter.Fill(dt);
        }
        finally
        {
            con.Close();
        }

        DropDownList list = RGGSTAcCode.FindControl("ddlAcCode") as DropDownList;
        list.DataTextField = "AccountDescription";
        list.DataValueField = "AccountCodeID";
        list.DataSource = dt;
        list.DataBind();
    }
    else
    {
        Response.Write("Please select Company first");
    }
}

现在，当我尝试使用 "ddlCompany_SelectedIndexChanged" 事件更改公司时，

我得到以下错误：
System.NullReferenceException: 对象引用未设置到对象的实例。
行：
list.DataTextField = "AccountDescription";

请指出我的代码有什么问题。提前致谢

Answer 1

此行包含错误下拉列表未正确找到

DropDownList list = RGGSTAcCode.FindControl("ddlAcCode") as DropDownList;

您将 Dropdown 放置在任何控件中的什么位置..？？

访问这个linkhttp://docs.telerik.com/devtools/aspnet-ajax/controls/grid/how-to/operations-with-ms-dropdownlist-in-edititemtemplate-of-gridtemplatecolumn

Answer 2

试试这个

 foreach (GridDataItem item in RGGSTAcCode.EditItems)
{
    DropDownList list = item.FindControl("ddlAcCode") as DropDownList;
    //Now we can do stuff with the "list"
}

请记住，该行需要处于编辑模式才能在其 EditItemTemplate 中找到控件。

Dropdown "SelectedIndexChanged" 事件中的错误，同时从 RadComboBox 中选择新项目

Error in Dropdown "SelectedIndexChanged" event, while Seleting new item from RadComboBox

c#

asp.net

radcombobox