DropDownLists,On Selected Index Changed 仅在按下另一个按钮时运行 - C#

DropDownLists, On Selected Index Changed only runs when another button pressed - C#

所以基本上,我想让我的 DropDownList 更新分配给它的数字,具体取决于它是几月。 (例如,如果有人选择二月,它会更新日期下拉列表以限制那里显示的数字数量。)

但是,我的问题是,只要代码是 运行,它就不会在更改月份时更新。从我的断点来看,只有 运行 当页面上的另一个按钮被单击时,THEN 事件才会 运行。这是一个奇怪的问题,我一直在摆弄它无济于事。

我的 HTML 下拉列表:

<asp:DropDownList ID="ddlMonthCI" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddlMonthCI_SelectedIndexChanged"/>

通过尝试 EnableViewState="true" 和其他一些小事情来解决这个问题几次,但没有任何效果。

点击此按钮后,代码为 运行:

<asp:Button runat="server" ID="CheckAvailability" Text="CHECK" OnClick="CheckAvailability_Click" CssClass="tsc_c3b_white tsc_button" />

我当前的 C# 代码

 protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        FillDropDowns();
        ddlMonthCI_SelectedIndexChanged(sender, e);
    }
}

protected void FillDropDowns()
{
    //A new int array created to hold 31 numbers
    var x = System.DateTime.Now;
    //For every 'i' (day), starting at one, and less than 31, incremement.
    for (int i = 1; i < 32; i++)
    {
        ddlDayCI.Items.Add(i.ToString());
        ddlDayCO.Items.Add(i.ToString());
    }
    ddlDayCI.Items.FindByValue(x.Day.ToString()).Selected = true;
    ddlDayCO.Items.FindByValue(x.Day.ToString()).Selected = true;

    //A new array created to hold months of the year
    for (int i = 1; i < 13; i++)
    {
        ddlMonthCI.Items.Add(i.ToString());
        ddlMonthCO.Items.Add(i.ToString());
    }
    ddlMonthCI.Items.FindByValue(x.Month.ToString()).Selected = true;
    ddlMonthCO.Items.FindByValue(x.Month.ToString()).Selected = true;

    for (int i = x.Year; i <= (x.Year + 1); i++)
    {
        ddlYearCI.Items.Add(i.ToString());
        ddlYearCO.Items.Add(i.ToString());
    }
}

protected void ddlMonthCI_SelectedIndexChanged(object sender, EventArgs e)
{
    DateTime sysdate = DateTime.Now;
    int selectedYear = Convert.ToInt32(ddlYearCI.SelectedItem.Text);
    int selectedMonth = Convert.ToInt32(ddlMonthCI.SelectedItem.Text);
    int totaldaysinthismonth = System.DateTime.DaysInMonth(selectedYear, selectedMonth);

    ddlDayCI.Items.Clear();

    for (int i = 1; i <= totaldaysinthismonth; i++)
    {
        ddlDayCI.Items.Add(i.ToString());
    }
}

我错过了有关检查可用性的 onClick 方法,因为我认为它不相关。但是,如果您希望我 post 我会的。

在页面加载中,FillDropDowns();方法是 运行,但是 ddlMonthCI_SelectedIndexChanged 也是如此。我把它放在那里是因为它只有 运行 当那是 运行.

有什么想法吗?

根据要求 -

protected void CheckAvailability_Click(object sender, EventArgs e)
{
    int yearCI = Convert.ToInt32(ddlYearCI.SelectedItem.Value);
    int monthCI = Convert.ToInt32(ddlMonthCI.SelectedItem.Value);
    int dayCI = Convert.ToInt32(ddlDayCI.SelectedItem.Value);
    DateTime dateOfCheckIn = new DateTime(yearCI, monthCI, dayCI);

    int yearCO = Convert.ToInt32(ddlYearCO.SelectedItem.ToString());
    int monthCO = Convert.ToInt32(ddlMonthCO.SelectedItem.ToString());
    int dayCO = Convert.ToInt32(ddlDayCO.SelectedItem.ToString());
    DateTime dateOfCheckOut = new DateTime(yearCO, monthCO, dayCO);

    //If checking out is before checking in date
    if (dateOfCheckOut < dateOfCheckIn)
    {
        Page.ClientScript.RegisterStartupScript(this.GetType(),"Scripts","<script>alert('INCORRECT DATE FORMAT');</script>" );            
    }
    //If checking out is after checking in date
    else if (dateOfCheckOut > dateOfCheckIn)
    {
        //Finds the current systems date
        DateTime sysdate = DateTime.Now;
        //If the current system date is after the check in, or its after the check out
        if (sysdate > dateOfCheckIn || sysdate > dateOfCheckOut)
        {
            Page.ClientScript.RegisterStartupScript(this.GetType(), "Scripts", "<script>alert('Please book AFTER todays date');</script>");
        }
        //else it'll run this
        else
        {
            DLDbContext context = new DLDbContext();
            //Counts how many versions of that room exists
            var roomType = ddlRoomType.SelectedItem.ToString();
            int RoomTypes = (from u in context.Room where u.roomType == roomType select u).Count();
            //Counts how many booked rooms there is, with the same room type.
            int BookedRooms = (from b in context.Booking where b.arrivalDate >= dateOfCheckIn && b.departureDate <= dateOfCheckOut && b.RoomType == roomType select b).Count();

            //If there's less booked rooms, than the amount of Rooms of that type it'll run this
            if (BookedRooms < RoomTypes)
            {

                //Passes current dates of checking in, checking out and roomtype to booking page
                Session.Add("checkIn", dateOfCheckIn);
                Session.Add("checkOut", dateOfCheckOut);
                Session.Add("roomType", roomType);
                Response.Redirect("BookingOverview.aspx");
            }
            //Else run this
            else
            {
                //Unavailable
                Page.ClientScript.RegisterStartupScript(this.GetType(), "Scripts", "<script>alert('Date is unavailable');</script>");
            }
        }
    }
}

我发现了我的错误。我 运行 一个测试站点来确认这不是我的愚蠢(而且是正确的)。

错误来自我使用的 UI 模板,其中包含

<form id="reservation-form">
   <form runat="server">
<!-- Stuff in here -->
</form>
</form>

导致问题的是第一种形式,我不知道为什么,我也无法为第二种形式提供该 ID 以继续 CSS class,因为它没有无法正常工作。

但是,删除它后,下拉列表可以正常工作。