ASP.NET codebehind can't get selected drop down list value (after set Javascript attribute)-CodePudding

anyone know how does it cause ASP.NET codebehind can't acquire the selected value.

What I found is the problem is the javascript function;

set attribute portion:

process.options[process.selectedIndex].setAttribute("style", "color:red;font-weight:600;");
process.options[process.selectedIndex].setAttribute("disabled", "disabled");

If I remove these setAttribute portion, ASP.NET codebehind can acquire the selected value.

Any solutions? If I insist want to use the setAttribute portion

Sample:

HTML

    <html>
    <table style="margin-left: auto; text-align: center; margin-right: auto; font-size: large; width: 50%" border="1">
                <tr>
                    <td >Process Name</td>
                    <td >:</td>
                    <td >
                        <asp:DropDownList ID="ddl_processname" runat="server" CssClass="ddl-style" onchange="focustester()">
<asp:ListItem Value="P1">Process 1</asp:ListItem>
                        <asp:ListItem Value="P2">Process 2</asp:ListItem>
                        <asp:ListItem Value="P3">Process 3</asp:ListItem></asp:DropDownList>
                        <br />
                        <br />
                        <asp:Label ID="lbl_statio" runat="server" Text=""></asp:Label>
                    </td>
                </tr>
                <tr>
                    <td >Tester Name</td>
                    <td >:</td>
                    <td >
                        <asp:TextBox ID="txt_testername" runat="server" AutoPostBack="true" OnTextChanged="TextBox_TextChanged" CssClass="txt-style"></asp:TextBox>
                    </td>
                </tr>
            </table>
        </div>
        <script>
            function focustester() {
                var process = document.getElementById('<%= ddl_processname.ClientID%>');
    
                if (process.value != "") {
                    process.options[process.selectedIndex].setAttribute("style", "color:red;font-weight:600;");
                    process.options[process.selectedIndex].setAttribute("disabled", "disabled");
    
    
                    document.getElementById('<%= txt_testername.ClientID%>').focus();
                }
            }
        </script>
        </html>

ASP.NET code behind

protected void TextBox_TextChanged(object sender, EventArgs e)
        {
            TextBox txt_ID = (TextBox)sender;
            string get_certain_box = "";

            if (ddl_processname.SelectedValue.ToString() == "")
            {
                Response.Write(@"<script language=javascript>alert('Please select Process first...')</script>");
                txt_ID.Text = "";
                ddl_processname.Focus();
            }
            else
            {
                if (txt_ID.Text.ToString() == "")
                {
                    get_certain_box = (txt_ID.ID.ToString() == "txt_testername") ? "Tester field" : "txtID";
                    Response.Write(@"<script language=javascript>alert('"   get_certain_box   " cannot blank...')</script>");
                    txt_ID.Focus();
                }
                else
                {
                    if (txt_ID.ID.ToString() == "txt_testername")
                    {
                       Response.Write(@"<script language=javascript>alert('success')</script>");
                    }

                }
            }
        }

CodePudding user response：

I maybe wrong but I remember that code behind can't get data if the dropdown is disabled or something. So can you just disable dropdown after it go to focustester() ? but if you insist to use JavaScript then why not workaround like insert value into hidden field when using setAttribute?

CodePudding user response：

Add a hidden field. And then assign dropdown value to hidden field in javascript. In the server side access the hidden value for dropdown value.

<asp:HiddenField ID="hdnProcess" runat="server" />

Javascript

function focustester() {
                var process = document.getElementById('<%= ddl_processname.ClientID%>');
    
                if (process.value != "") {
                    process.options[process.selectedIndex].setAttribute("style", "color:red;font-weight:600;");
                    process.options[process.selectedIndex].setAttribute("disabled", "disabled");
                    

                    var hdn = document.getElementById('<%=hdnProcess.ClientID%>');
                    hdn.value = process.value;

    
                    document.getElementById('<%= txt_testername.ClientID%>').focus();
                }
            }

Server Side

protected void txt_testername_TextChanged(object sender, EventArgs e)
    {
        {
            TextBox txt_ID = (TextBox)sender;
            string get_certain_box = "";
            string ddlval = hdnProcess.Value.ToString();

            if (ddlval == "")
            {
                Response.Write(@"<script language=javascript>alert('Please select Process first...')</script>");
                txt_ID.Text = "";
                ddl_processname.Focus();
            }
            else
            {
                if (txt_ID.Text.ToString() == "")
                {
                    get_certain_box = (txt_ID.ID.ToString() == "txt_testername") ? "Tester field" : "txtID";
                    Response.Write(@"<script language=javascript>alert('"   get_certain_box   " cannot blank...')</script>");
                    txt_ID.Focus();
                }
                else
                {
                    if (txt_ID.ID.ToString() == "txt_testername")
                    {
                        Response.Write(@"<script language=javascript>alert('success')</script>");
                    }

                }
            }
        }
    }