Dropdownlist问题

[yuanweiming841103]

Private Sub DgEditRole_EditCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridCommandEventArgs) Handles DgEditRole.EditCommand
Dim PerDdlRoleName As DropDownList = e.Item.FindControl("DdlRoleName")
Dim RoleName As String = PerDdlRoleName.SelectedItem.Text ''''''''出错的语句
Response.Write(PerDdlRoleName.SelectedItem.Text)
End Sub

错误提示：未将对象引用到实例
要找的控件id DdlRoleName是绝对没有错的
dropdownlist控件我是加在datagrid的edit模板中
请问这个错误是什么原因，应该这么解决？
在线等

[gsk99]

那么你就加一句如果e.Item.FindControl("DdlRoleName")他不位null的话，再进行你的操作试试看
if(e.Item.FindControl("DdlRoleName")!=null)
...\\这个市C#的，vb的不知道怎么写

[Eddie005]

这是事件的先后顺序的问题：
因为dropdownlist是在editItem里的，当点击edit按钮触发EditCommand事件时，这个dropdownlist都还没有生成，肯定找不到

[Eddie005]

正确的实现方法是：

private void DataGrid1_EditCommand(object source, System.Web.UI.WebControls.DataGridCommandEventArgs e)
{
DataGrid1.EditItemIndex = e.Item.ItemIndex;
DataGrid1.DataSource = dt;//需要重新绑定
DataGrid1.DataBind();
}

private void DataGrid1_ItemCreated(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e)
{
if(e.Item.ItemType == ListItemType.EditItem)
{
DropDownList ddlst = e.Item.FindControl("dropdownlist1") as DropDownList;
ddlst.Items.Add("abc");//这里就可以找到
}
}

private void DataGrid1_UpdateCommand(object source, System.Web.UI.WebControls.DataGridCommandEventArgs e)
{
DropDownList ddlst = e.Item.FindControl("dropdownlist1") as DropDownList;//这里也可以找到
Response.Write(ddlst.SelectedValue );
}

[job_2006]

顶

[Eddie005]

vb语法就是
Private Sub DataGrid1_EditCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridCommandEventArgs) Handles DataGrid1.EditCommand
Me.DataGrid1.EditItemIndex = e.Item.ItemIndex
End Sub

Private Sub DataGrid1_ItemCreated(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs) Handles DataGrid1.ItemCreated
Dim ddlst As DropDownList = e.Item.FindControl("dropdownlist1")
ddlst.SelectedIndex = 0
End Sub

Private Sub DataGrid1_UpdateCommand(ByVal source As Object, ByVal e As System.Web.UI.WebControls.DataGridCommandEventArgs) Handles DataGrid1.UpdateCommand
Dim ddlst As DropDownList = e.Item.FindControl("dropdownlist1")
Response.Write(ddlst.SelectedValue)
End Sub

[yuanweiming841103]

还是不行啊

[yuanweiming841103]

Private Sub DgEditRole_ItemCreated(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs) Handles DgEditRole.ItemCreated
Dim PerDdlRoleName As DropDownList = e.Item.FindControl("DdlRoleName")
Dim RoleName As String = PerDdlRoleName.SelectedItem.Text
Response.Write(PerDdlRoleName.SelectedItem.Text)
End Sub
这样加了，还是报那个错，同一个地方

[yuanweiming841103]

数据我是直接在属性里面添加的，而且有select选项等于true，所以应该不是数据的问题

[Eddie005]

漏了判断条件了
Private Sub DataGrid1_ItemCreated(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.DataGridItemEventArgs) Handles DataGrid1.ItemCreated
if e.Item.ItemType = ListItemType.EditItem then

Dim ddlst As DropDownList = e.Item.FindControl("dropdownlist1")
ddlst.SelectedIndex = 0
end if
End Sub

[yuanweiming841103]

强顶
谢谢了