Hi thereIn the aspx page I have two drop down listslt Page Language34C34 AutoEventWireup34true34 CodeFile34Defaultaspxcs34 Inherits34Default34 gtltDOCTYPE htmlgtlthtml xmlns34httpwwww3org1999xhtml34gtlthead runat34server34gt ltmeta httpequiv34ContentType34 content34texthtml charsetutf834 gt lttitlegtlttitlegtltheadgtltbodygt ltform id34form134 runat34server

Hi theunclevinceRefer below codeHTML You need to make use of OnSelectedIndexChanged event handler of DropDownList to make changes on change of yearltdivgt ltaspDropDownList ID34ddlYears34 runat34server34 AutoPostBack34true34 OnSelectedIndexChanged34OnSelectedIndexChanged34gt ltaspListItem Text34Select34 Value3434gtltaspListItemgt ltaspListItem Text34202634 Value34202634gtltaspListItemgt ltaspListItem Text34202534 Value34202534gtltaspListItemgt ltaspListItem Text34202434 Value34202434gtltaspListItemgt ltaspDropDownListgtltdivgtltbr gtltdivgt ltaspDropDownList ID34ddlMonths34 runat34server34gt ltaspDropDownListgtltdivgtNamespacesusing SystemGlobalizationCodeprotected void PageLoadobject sender EventArgs e DateTime dateTime DateTimeNow List of

Future ASP.Net DropDownList Years and Months selection validation in C#

theuncle...

SOLVED CLOSED ACTIVE ANSWERED
User: theunclevince
Posted: on Feb 20, 2025 02:26 AM
Forum: ASP.Net Web Forms
Answer: 1
Views: 1277
Sample Code: Download

Hi there,

In the aspx page I have two drop down lists

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title></title>
</head>
<body>
    <form id="form1" runat="server">

        <div>
            <asp:DropDownList ID="ddlYears" runat="server">
                <asp:ListItem Text="Select" Value=""></asp:ListItem>
                <asp:ListItem Text="2025" Value="2025"></asp:ListItem>
                <asp:ListItem Text="2024" Value="2024"></asp:ListItem>
            </asp:DropDownList>
        </div>

        <br />

        <div>
            <asp:DropDownList ID="ddlMonths" runat="server">
                <asp:ListItem Text="Select" Value=""></asp:ListItem>
                <asp:ListItem Text="JAN" Value="1"></asp:ListItem>
                <asp:ListItem Text="FEB" Value="2"></asp:ListItem>
                <asp:ListItem Text="MAR" Value="3"></asp:ListItem>
                <asp:ListItem Text="APR" Value="4"></asp:ListItem>
                <asp:ListItem Text="MAY" Value="5"></asp:ListItem>
                <asp:ListItem Text="JUN" Value="6"></asp:ListItem>
                <asp:ListItem Text="JUL" Value="7"></asp:ListItem>
                <asp:ListItem Text="AUG" Value="8"></asp:ListItem>
                <asp:ListItem Text="SEP" Value="9"></asp:ListItem>
                <asp:ListItem Text="OCT" Value="10"></asp:ListItem>
                <asp:ListItem Text="NOV" Value="11"></asp:ListItem>
                <asp:ListItem Text="DEC" Value="12"></asp:ListItem>
            </asp:DropDownList>
        </div>
    </form>
</body>

I have to warn the user when he selects a year month value that is not yet present.

For example if today I select year 2025 and month June I have to warn that the selection is invalid.

How can I do this? My code below

protected void Page_Load(object sender, EventArgs e)
{
    DateTime dateTime = DateTime.Now;
 
    // List of Months to be display.
    List<ListItem> months = new List<ListItem>();
    for (int i = 1; i <= 8; i++)
    {
        months.Add(ddlMonths.Items.Cast<ListItem>()
                            .Where(x => x.Value.Equals(dateTime.AddMonths(-i).Month.ToString()))
                            .FirstOrDefault());
    }
 
    //Determines first item i.e.Equals Default Item.
    ListItem defaultItem = ddlMonths.Items[0];
 
    //Clears all items in the DropDownList.
    ddlMonths.Items.Clear();
 
    //Reverse the List of last two months.
    months.Reverse();
 
    //Inserts Default Item.
    months.Insert(0, defaultItem);
 
    //Assigning month to DropDownList.
    ddlMonths.DataSource = months;
    ddlMonths.DataBind();
}

Download FREE API for Word, Excel and PDF in ASP.Net

mohammad...

0 3

Reply
ANSWER
User: mohammadumarsk684
Replied: on Feb 20, 2025 10:43 AM
Report

Hi theunclevince,

Refer below code.

HTML

You need to make use of OnSelectedIndexChanged event handler of DropDownList to make changes on change of year.

<div>
    <asp:DropDownList ID="ddlYears" runat="server" AutoPostBack="true" OnSelectedIndexChanged="OnSelectedIndexChanged">
        <asp:ListItem Text="Select" Value=""></asp:ListItem>
        <asp:ListItem Text="2026" Value="2026"></asp:ListItem>
        <asp:ListItem Text="2025" Value="2025"></asp:ListItem>
        <asp:ListItem Text="2024" Value="2024"></asp:ListItem>
    </asp:DropDownList>
</div>
<br />
<div>
    <asp:DropDownList ID="ddlMonths" runat="server">
    </asp:DropDownList>
</div>

Namespaces

using System.Globalization;

Code

protected void Page_Load(object sender, EventArgs e)
{
    DateTime dateTime = DateTime.Now;

    // List of Months to be display.
    List<ListItem> months = new List<ListItem>();

    DateTimeFormatInfo info = DateTimeFormatInfo.GetInstance(null);

    //Binding All months
    for (int i = 1; i < 13; i++)
    {
        months.Add(new ListItem(info.GetMonthName(i), i.ToString()));
    }

    ddlMonths.DataSource = months;
    ddlMonths.DataBind();
    ddlMonths.Items.Insert(0, new ListItem("--Select--"));
}

protected void OnSelectedIndexChanged(object sender, EventArgs args)
{
    DateTime dateTime = DateTime.Now;

    // List of Months to be display.
    List<ListItem> months = new List<ListItem>();

    DateTimeFormatInfo info = DateTimeFormatInfo.GetInstance(null);

    int selectedDate = int.Parse(ddlYears.SelectedItem.Text);

    if (selectedDate == dateTime.Year)
    {
        //Bind only Current month and previous months.
        for (int i = 1; i <= dateTime.Month; i++)
        {
            months.Add(new ListItem(info.GetMonthName(i), i.ToString()));
        }
    }
    else if (selectedDate > dateTime.Year)
    {
        //No Months
    }
    else
    {
        for (int i = 1; i < 13; i++)
        {
            months.Add(new ListItem(info.GetMonthName(i), i.ToString()));
        }
    }
    ddlMonths.DataSource = months;
    ddlMonths.DataBind();
    ddlMonths.Items.Insert(0, new ListItem("--Select--"));
}

Screenshot

Glad to assist!

I agree, here is the link: https://www.e-iceblue.com/Introduce/spire-office-for-net-free.html

Future ASP.Net DropDownList Years and Months selection validation in C#

Company

Explore

Follow us

Contact Us