Question

以下代码; 代码不返回值空字符串

private void DisplayDplace()
    {
        BusinessLogicLayer.Businesslogiclayer objll = new BusinessLogicLayer.Businesslogiclayer();
    DataSet ds = objll.Binddname();
    drpfromplace.DataSource = ds;
    drpfromplace.DataTextField = "dname";
    drpfromplace.DataValueField = "did";
    drpfromplace.DataBind();
    drptoplace.DataSource = ds;
    drptoplace.DataTextField = "dname";
    drptoplace.DataValueField = "did";
    drptoplace.DataBind();
}

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        DisplayDplace();
    }
}

protected void Calendar1_SelectionChanged1(object sender, EventArgs e)
{
    TextBox1.Text = Calendar1.SelectedDate.ToShortDateString();
}

protected void Button1_Click(object sender, EventArgs e)
{
    Session["doj"] = TextBox1.Text;
    Session["noofseats"] = DropDownList6.SelectedItem.ToString();
    Session["fd"]= drpfromplace.SelectedItem.Value.ToString();
    Session["td"] = drptoplace.SelectedItem.Value.ToString();
}

}

Answer 1

如果你想获得dropdown的值，那么你将不得不使用像javascript / jquery那样的客户端脚本。如果你想获得代码背后的值，那么你需要创建一个ajax调用。

在后面的代码中创建一个webmethod：

[WebMethod]
        public static string MyWebMethod(string name )
        {
            /your logic goes here
            return ("Yeey");
        }

现在在aspx.cs上创建一个Ajax调用：

$('#mybutton').on('click',function(){

 $.ajax({
            type: "POST",
            url: "Default.aspx/MyWebMethod",
            data: JSON.stringify({ name: $('#drpname').val() }),
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            async: true,
            success: function (data, status) {
                alert("victory");
            },               
            failure: function (data) {
                alert(data.d);
            },
            error: function (data) {
                alert(data.d);
            }
        });

});

Answer 2

您可以向页面添加ScriptManager并将代码包装在UpdatePanel内。

   <asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>

    <asp:UpdatePanel ID="UpdatePanel1" runat="server">
        <ContentTemplate>

            <asp:DropDownList ID="DropDownList1" runat="server">
                <asp:ListItem Text="A" Value="a"></asp:ListItem>
                <asp:ListItem Text="B" Value="b"></asp:ListItem>
            </asp:DropDownList>
            <br />
            <asp:Button ID="Button1" runat="server" Text="getValue" OnClick="Button1_Click" />
            <br />
            <asp:Label ID="Label1" runat="server" Text=""></asp:Label>

        </ContentTemplate>
    </asp:UpdatePanel>

背后的代码与以往一样。

    protected void Button1_Click(object sender, EventArgs e)
    {
        Label1.Text = DropDownList1.SelectedValue;
    }

如何获得下拉选择的索引值而无需回发并单击按钮

2 个答案: