Question

SelectedIndexChanged仅在表单提交后起作用。如果我从drpdown列表中选择数据，它会选择索引并将数据从数据库获取到texboxes。但是如果我单击Submit按钮，它将显示数据

我尝试使用回发，但是没有用。是否有解决此问题的替代方法。

HTML

<div class="col-md-4">
   <asp:Label ID="Label10" runat="server" Text="Related Word"></asp:Label>
   <asp:UpdatePanel ID="update" runat="server">
      <ContentTemplate>
         <asp:TextBox ID="txtRelatedWord" runat="server" class="form-control"  AutoPostBack="true" OnTextChanged="txtRelatedWord_TextChanged" placeholder="Word"  ></asp:TextBox>
      </ContentTemplate>
      <Triggers>
         <asp:AsyncPostBackTrigger ControlID="txtRelatedWord" EventName="TextChanged" />
      </Triggers>
   </asp:UpdatePanel>
</div>
<div class="col-md-4" style="margin-top:37px">
   <asp:UpdatePanel ID="UpdatePanel2" runat="server">
      <ContentTemplate>
         <asp:DropDownList ID="cmbRelatedWord" CssClass="form-control" AutoPostBack="true" OnSelectedIndexChanged="cmbRelatedWord_SelectedIndexChanged" runat="server" >
         </asp:DropDownList>
      </ContentTemplate>
      <Triggers>
         <asp:AsyncPostBackTrigger ControlID="cmbRelatedWord" EventName="SelectedIndexChanged" />
      </Triggers>
   </asp:UpdatePanel>
</div>

隐藏代码

private static void InsertRequest(ref RequestModel model, string connection) 
{
  using(var con = new SqlConnection(connection)) 
  {
   using(var cmd = new SqlCommand("Insert into infromationRequests (Gender, Age, IsMedicine, IsTransplant, Operations, ResponseJson) values (@Gender, @Age, @IsMedicine, @IsTransplant, @Operations, NULL); SELECT SCOPE_IDENTITY();", con)) 
   {
       cmd.Parameters.AddWithValue("@Gender", model.Gender);
       cmd.Parameters.AddWithValue("@Age", model.Age);
       cmd.Parameters.AddWithValue("@IsMedicine", model.Medicine);
       cmd.Parameters.AddWithValue("@IsTransplant", model.Transplant);
       cmd.Parameters.AddWithValue("@Operations", model.Operations);
       con.Open();

       model.Id = Convert.ToInt32(cmd.ExecuteScalar());

       con.Close();
   }
  }
}

Answer 1

好吧，我设法做了一个简单的测试，效果很好：

返回：

public partial class Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Console.WriteLine("Load triggered");
    }

    protected void ddlist_SelectedIndexChanged(object sender, EventArgs e)
    {
        Console.WriteLine("event triggered");
        tb.Text = (sender as DropDownList).SelectedValue;
    }
}

前面：

<asp:ScriptManager runat="server" ID="smanager"></asp:ScriptManager>
        <asp:UpdatePanel runat="server" ID="upanel">
            <ContentTemplate>
                <asp:DropDownList ID="ddlist" runat="server" OnSelectedIndexChanged="ddlist_SelectedIndexChanged" AutoPostBack="true">
                    <asp:ListItem Text="1" Value="1"></asp:ListItem>
                    <asp:ListItem Text="2" Value="2"></asp:ListItem>
                </asp:DropDownList>
                <asp:TextBox runat="server" ID="tb" Text="Default"></asp:TextBox>
            </ContentTemplate>
            <Triggers>
                <asp:AsyncPostBackTrigger ControlID="ddlist" EventName="SelectedIndexChanged" />
            </Triggers>
        </asp:UpdatePanel>

据此，我可以为您提供这些线索：

您是否尝试将两个组件都放在同一“更新”面板中？
您确定未触发事件吗？还是mayeb，您只是没有在页面中使用任何回发检查？如果您不检查页面是否是页面加载时的回发，那么将在触发偶数之前重新加载组件内容。

SelectedIndexChanged仅在单击按钮后触发

1 个答案: