为什么SelectedIndexChanged事件不是从GridView中的下拉列表触发的？

Question

我无法触发我的下拉列表的SelectedIndexChanged.我有以下内容:

<form id="form1" runat="server">
<div>
<asp:GridView id="grdPoll" runat="server" AutoGenerateColumns="false">
    <Columns>
        <asp:TemplateField>
            <ItemTemplate>
                <asp:DropDownList ID="DropDownList1" runat="server" 
                 AutoPostBack="true"
                 OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
                    <asp:ListItem Text="Review" Value="Review" Selected="True">Review</asp:ListItem>
                    <asp:ListItem Text="Level1" Value="lvl1">Send Back to Level1</asp:ListItem>
                </asp:DropDownList>
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

<asp:Label ID="lblCity" runat="server" Text="Label"></asp:Label>  
</div>
</form>

在我的代码背后我有这个:

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
    this.lblCity.Text = ((DropDownList)sender).SelectedValue;
}

如果我把这个相同的ddl放在gridview之外,它就会触发.

回发正在发生,autopostback设置为true.事件永远不会发生.为什么我不能在gridview中触发我的事件？

谢谢.

Answer 1

好吧,这个问题是在一个多月前提出的,现在可能无关紧要,但是@LFSR最近很友好地编辑它,它在"活动问题"列表中.

既然没有答案(224次观看!),我想我应该试一试:

问题是在GridView的上下文中,DropDownList(以下称为DDL)是一个动态控件,因此它的事件需要在Postback上重新附加.

理解这个概念后,解决方案变得相对简单:

ASPX:

<asp:DropDownList ID="DDL1" runat="server" AutoPostBack="true" OnSelectedIndexChanged="DDL1_SelectedIndexChanged">
  <asp:ListItem Text="Review" Value="Review" Selected="True">Review</asp:ListItem>
  <asp:ListItem Text="Level1" Value="lvl1">Send Back to Level1</asp:ListItem>
</asp:DropDownList>

CS代码:

protected void Page_Load(object sender, EventArgs e)
{
  if(!Page.IsPostBack)
  {
    // Bind the GridView to something.
    DataBindGrid();
  }
}

protected void DDL1_SelectedIndexChanged(object sender, EventArgs e)
{
  this.lblCity.Text = ((DropDownList)sender).SelectedValue;
}

protected void grdPoll_RowDataBound(object sender, GridViewRowEventArgs e)
{
  if(Page.IsPostBack)
  {
    if(e.Row.RowType == DataControlRowType.DataRow)
    {
      DropDownList ddl = e.Row.FindControl("DDL1") as DropDownList;
      if(ddl != null)
      {
        ddl.SelectedIndexChanged += new EventHandler(DDL1_SelectedIndexChanged);
      }
    }
  }
}