为什么SelectedIndexChanged事件从GridView中的下拉列表中触发？ [英] Why isn't the SelectedIndexChanged event firing from a dropdownlist in a GridView?

问题描述

我无法让我的SelectedIndexChanged我的下拉列表触发。我有以下内容：

 < form id =form1runat =server> 
< div> 
< asp：GridView id =grdPollrunat =serverAutoGenerateColumns =false> 
<列> 
< asp：TemplateField> 
< ItemTemplate> 
< asp：DropDownList ID =DropDownList1runat =server
 AutoPostBack =true
 OnSelectedIndexChanged =DropDownList1_SelectedIndexChanged> 
< asp：ListItem Text =ReviewValue =ReviewSelected =True> Review< / asp：ListItem> 
< asp：ListItem Text =Level1Value =lvl1>发送回Level1< / asp：ListItem> 
< / asp：DropDownList> 
< / ItemTemplate> 
< / asp：TemplateField> 
< / Columns> 
< / asp：GridView> 
 
< asp：Label ID =lblCityrunat =serverText =Label>< / asp：Label> 
< / div> 
< / form> 
  

在我的代码背后我有这样的：

  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外面，它会触发。 p>

回发正在发生，并且autopostback设置为true。事件永远不会触发。为什么我不能让我的事件从gridview中触发？

谢谢。

解决方案

嗯，这个问题是在一个多月前被问到的，现在可能是无关紧要的，但是@LFSR最近很好地编辑它，它在活动问题列表中。

由于它仍然没有得到答复（224次观看），我以为我应该去一个：

---

问题是在GridView的上下文中，DropDownList（以下称为DDL）是一个动态控件，因此其事件需要在Postback上重新连接。

当这个概念被理解时，解决方案变得相对简单：

ASPX：

 < asp：DropDownList ID =DDL1runat =serverAutoPostBack =trueOnSelectedIndexChanged =DDL1_SelectedIndexChanged> 
< asp：ListItem Text =ReviewValue =ReviewSelected =True> Review< / asp：ListItem> 
< asp：ListItem Text =Level1Value =lvl1>发送回Level1< / asp：ListItem> 
< / asp：DropDownList> 
  

CS代码：

  protected void Page_Load（object sender，EventArgs e）
 {
 if（！Page.IsPostBack）
 {
 //将GridView绑定到某个东西。 
 DataBindGrid（）; 
} 
} 
 
 protected void DDL1_SelectedIndexChanged（object sender，EventArgs e）
 {
 this.lblCity.Text =（（DropDownList）sender）。的SelectedValue; 
} 
 
 protected void grdPoll_RowDataBound（object sender，GridViewRowEventArgs e）
 {
 if（Page.IsPostBack）
 {
 if（e .Row.RowType == DataControlRowType.DataRow）
 {
 DropDownList ddl = e.Row.FindControl（DDL1）作为DropDownList; 
 if（ddl！= null）
 {
 ddl.SelectedIndexChanged + = new EventHandler（DDL1_SelectedIndexChanged）; 
} 
} 
} 
} 
  

I cannot get my SelectedIndexChanged of my dropdownlist to fire. I have the following:

<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>

In my code behind I have this:

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

If I put this same ddl outside of the gridview, it fires.

The postback is occurring and the autopostback is set to true. The event just never fires. Why can't I get my event to fire from within the gridview?

Thank you.

解决方案

Well, this question was asked more than a month ago and may be irrelevant now, but @LFSR was kind enough to edit it recently, it's in the "Active questions" list.

Since it remains unanswered (224 views!), I thought I should give it a go:

---

The problem is that in the context of a GridView, the DropDownList(referred to hereafter as DDL) is a dynamic control and therefore its events need to be reattached upon Postback.

When this concept is understood, the solution becomes relatively simple :

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 Code:

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);
      }
    }
  }
}

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