help me! Gridview 内DropDownList的更新不了,提示:"无法将类型为“System.Web.UI.LiteralControl”的对象强制转换为类型“System.Web.UI.WebControls.DropDownList”"

Question

 protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {
        //string gg = ((DropDownList)GridView1.Rows[e.RowIndex].FindControl("ggxh")).SelectedItem.Text;
        int bid =Convert.ToInt16(this.GridView1.DataKeys[e.RowIndex].Value);
        SqlConnection cn = new SqlConnection(ConfigurationManager.AppSettings["local"]);
        string update = "update bom set ggxh=@ggxh where BID =@bid";
        SqlCommand cmd3 = new SqlCommand(update, cn);
        cmd3.Parameters.Add(new SqlParameter("@ggxh", SqlDbType.NVarChar, 50));
        cmd3.Parameters.Add(new SqlParameter("@bid", SqlDbType.Int, 4));        cmd3.Parameters["@ggxh"].Value = ((DropDownList)GridView1.Rows[e.RowIndex].Cells[2].Controls[0]).SelectedValue.ToString();         try
        {
            cn.Open();
            cmd3.ExecuteNonQuery();
            Response.Write("<script>alert('OK!')</script>");
        }        catch
        {
            Response.Write("<script>alert('NOT OK!')</script>");
        }
        finally
        {
            cmd3.Dispose();
            cn.Close();
        }
        this.GridView1.EditIndex = -1;
        BindGrid();
        
    }
取不到DropDownList.SelectedValue值,why?

Answer 1

((DropDownList)GridView1.Rows[e.RowIndex].Cells[2].Controls[0]).SelectedValue.ToString(); 
这句是肯定不对里

Answer 2

应该这样
((DropDownList)GridView1.Rows[e.RowIndex].FindControl("控件名称")).SelectedValue.ToString();

Answer 3

DropDownList DropDownList1 = GridView1.Rows[e.RowIndex].FindControl("DropDownList1") as DropDownList;
string value= DropDownList1 .SelectedValue;

Answer 4

不对，我是按03的思路写的CODE
那该怎么写啊？to :gaoliuchang 

Answer 5

to :gaoliuchang 
错误提示： to :gaoliuchang 

Answer 6

cmd3.Parameters["@ggxh"].Value = ((DropDownList)GridView1.Rows[e.RowIndex].Cells[2].Controls[0]).SelectedValue.ToString(); 
改成
cmd3.Parameters["@ggxh"].Value = ((DropDownList)GridView1.Rows[e.RowIndex].Cells[2].Controls[1]).SelectedValue.ToString(); 
试一下
原因：
你可以启用页面跟踪，Controls[0]一般是LiteralControl，而不是我们想要的那个控件

Answer 7

to :gaoliuchang 
错误提示：  未将对象引用设置到对象的实例

Answer 8

六楼正解 
可是 我的是 foreach(DropDownlist in panel1.Controls)
这种情况他也提示种错误， 如何是好