DropDownList 在GridView中取值更新问题？

Question

.aspxasp:GridView ID="GridViewSSort" runat="server" AutoGenerateColumns="False" OnRowCancelingEdit="GridViewSSort_RowCanelingEdit" OnRowEditing="GridViewSSort_RowEditing" OnRowUpdating="GridViewSSort_RowUpdating" OnRowDeleting="GridViewSSort_RowDeleting" OnRowDataBound="GridViewSSort_RowDataBound"  DataKeyNames="id" >
                              <Columns>
                                  <asp:BoundField DataField="id" HeaderText="ID" ReadOnly="True" SortExpression="id" />
                                  <asp:TemplateField HeaderText="大类名称">
                                      <ItemTemplate>
                                          <asp:HiddenField runat="server" ID="hidTxt" Value='<%#Bind("BSorID")%>' />
                                          <asp:DropDownList ID="ddlGVBSort" runat="server" >
                                          </asp:DropDownList>
                                      </ItemTemplate>
                                  </asp:TemplateField>
                                  <asp:BoundField DataField="SSortName" HeaderText="小类名称" SortExpression="SSortName" />
                                  <asp:CommandField ShowEditButton="True" />
                                  <asp:CommandField ShowDeleteButton="True" />
                              </Columns>
                              <EmptyDataTemplate> 
                                  <asp:DropDownList ID="ddlGVBSort" runat="server">
                                  </asp:DropDownList>
                              </EmptyDataTemplate>
                          </asp:GridView>
.cs更新
protected void GridViewSSort_RowUpdating(object sender, GridViewUpdateEventArgs e)  //小类
        {
            string strKeyId = GridViewSSort.DataKeys[e.RowIndex].Value.ToString();
            string strDDLValue = ((DropDownList)GridViewBSort.Rows[e.RowIndex].Cells[2].FindControl("ddlGVBSort")).SelectedValue;
            string strSSortName = ((TextBox)GridViewSSort.Rows[e.RowIndex].Cells[3].Controls[0]).Text.ToString();
            string strUpdate = "UPDATE Tb_Train_SSort SET BSorID='"+ strDDLValue +"',SSortName='" + strSSortName + "' WHERE id=" + strKeyId;
            int intResult = this.ExecuteNonQuery(strUpdate, dsn, database);
}
//RowBind
if (e.Row.RowType == DataControlRowType.DataRow)
            {
                if (e.Row.RowState == DataControlRowState.Normal || e.Row.RowState == DataControlRowState.Alternate)
                {
                    ((LinkButton)e.Row.Cells[4].Controls[0]).Attributes["onclick"] = "if(!confirm('你确定要删除“" + e.Row.Cells[1].Text + "”记录吗？')) return false;";
                }
                DropDownList dropTemp = (DropDownList)e.Row.Cells[0].FindControl("ddlGVBSort");
                string strSelect = "SELECT * FROM Tb_Train_BSort";
                DataTable dt = this.ExecuteReader(strSelect, dsn, database);
                if (dt != null && dt.Rows.Count > 0)
                {
                    dropTemp.DataSource = dt;
                    dropTemp.DataTextField = "BsortName";
                    dropTemp.DataValueField = "id";
                    dropTemp.DataBind();
                    dropTemp.SelectedValue = ((HiddenField)e.Row.FindControl("hidTxt")).Value.ToString();
                }
            }更新的时候报错：string strDDLValue = ((DropDownList)GridViewBSort.Rows[e.RowIndex].Cells[2].FindControl("ddlGVBSort")).SelectedValue;
为将对象引用实例，请问这个是怎么回事啊。

Answer 1

FindControl("ddlGVBSort")的问题
应该是这个控件没有找到，所以是空引用

Answer 2

this.GridView1.Rows[e.RowIndex].FindControl(“ddlGVBSort”)
是不是列指定错了，试下在行里面FindControl

Answer 3

是列错了，应该是Cell[0]，看你aspx页的代码，应该是[0]列

Answer 4

是不是因为 <asp:HiddenField runat="server" ID="hidTxt" Value=' <%#Bind("BSorID")%>' /> 的原因呢 <ItemTemplate> 
                                           <asp:HiddenField runat="server" ID="hidTxt" Value=' <%#Bind("BSorID")%>' /> 
                                           <asp:DropDownList ID="ddlGVBSort" runat="server" > 
                                           </asp:DropDownList> 
                                       </ItemTemplate> 

Answer 5

没错，应该是1.在行里FindControl也不行？

Answer 6

呵呵，昨天晚上正好在解决这个问题
看看这篇文章你应该能找到答案http://www.cnblogs.com/dushouke/archive/2008/03/27/1126232.html

Answer 7

点编辑
html代码
<td>10</td><td>
                                          <input type="hidden" name="GridViewSSort$ctl05$hidTxt" id="GridViewSSort_ctl05_hidTxt" value="11" />
                                          <select name="GridViewSSort$ctl05$ddlGVBSort" id="GridViewSSort_ctl05_ddlGVBSort">
<option selected="selected" value="11">管理</option>
<option value="12">营销</option>
<option value="13">技术</option>
<option value="14">生产</option> </select>
                                      </td><td><input name="GridViewSSort$ctl05$ctl00" type="text" title="小类名称" /></td><td><a href="javascript:__doPostBack('GridViewSSort$ctl05$ctl01','')">更新</a>&nbsp;<a href="javascript:__doPostBack('GridViewSSort','Cancel$3')">取消</a></td><td></td>

Answer 8

问题解决
由于控件名写错导致：
((DropDownList)GridViewBSort.Rows[e.RowIndex].Cells[2].FindControl("ddlGVBSort")).SelectedValue;
改成：((DropDownList)GridViewSSort.Rows[e.RowIndex].Cells[2].FindControl("ddlGVBSort")).SelectedValue;