c# - 从RadComboBox中删除新项目时，下拉菜单“SelectedIndexChanged”事件出错

在我的网页中，RadGrid之外有一个RadComboBox，RadGrid内有一个下拉菜单。

下拉列表中的数据是根据RadComboBox项目选择进行绑定的。
例如：如果从RadComboBox中选择了“公司”项，则下拉列表中的数据将与“公司”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：对象引用未设置为对象的实例。
在第：
list.DataTextField =“ AccountDescription”;

请提出我的代码有什么问题。提前致谢

最佳答案

该行包含错误下拉列表，无法正确找到

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

您将Dropdown放在任何控件中的什么位置？

访问此链接http://docs.telerik.com/devtools/aspnet-ajax/controls/grid/how-to/operations-with-ms-dropdownlist-in-edititemtemplate-of-gridtemplatecolumn

关于c# - 从RadComboBox中删除新项目时，下拉菜单“SelectedIndexChanged”事件出错，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/31265249/