选择的DropdownList值始终返回第一个值

Question

At the moment i have a method that retrieves a list of name from my database and return as an arraylist.

public static ArrayList GenerateFolderLocation(String username)
    {
        // Get User ID
        SqlDataReader sqlUserID = GetUserInformation(username);
        sqlUserID.Read();
        int userid = int.Parse(sqlUserID["userid"].ToString());

        SqlCommand cmd = new SqlCommand("SELECT distinct foldername FROM mb_folder WHERE userid=@userid", SQLGetMBoxConnection());
        cmd.Parameters.AddWithValue("@userid", userid);
        SqlDataReader sqldr = cmd.ExecuteReader();
        ArrayList locationList = new ArrayList();

        while (sqldr.Read())
        {
            locationList.Add(sqldr["foldername"].ToString());
        }
        locationList.Sort();
        return locationList;
    }

And in my page load method, i use DataSource and DataBind to fill up a dropdownlist i have on my main page. Note UploadLocation is the id of my dropdownlist

UploadLocation.DataSource= MBFolder.GenerateFolderLocation(Context.User.Identity.Name);
UploadLocation.DataBind();

And in my main page i have this dropdownlist and i also have a submit button

 <asp:DropDownList ID="UploadLocation" runat="server" 
         AutoEventWireup="true" EnableViewState="true">
 </asp:DropDownList>
<asp:Button ID="NewUploadFile" runat="server" Text="Upload" OnClick="NewUploadFile_Click" ValidationGroup="UploadFileValidation"  AutoPostBack="true"/>

What my problem is that when i click my submit button it fires the "NewUploadFile_Click" and in that method i want to retrieve the selected value of my dropdownlist. However right now i am able to retrieve the value but it is the first value in my dropdownlist. So for example, in my arraylist there would be (test1,test2,test3) and if i select "test2" my method would retrieve "test1" instead. In "NewUploadFile_click" i use UploadLocation.SelectedItem.Text; to get the selected value. What am i doing wrong? How can i retrieve the selected data. Thx

Answer 1

Try wrapping your list initialisation code within an !IsPostBack {} section in the PageLoad Event.

ie in Page_Load

if (!IsPostback)
{
 ... Initialise List here
}

Looks like you may be rebinding the list before you have got the data you need.

Answer 2

When you are calling a method to bind dropdownlist, try to add it inside In PageLoad event:

if(!IsPostBack)
{ 
    fillvalues();
}

So, It will not fire everytime you change your selections

Answer 3

Try setting AutoPostBack="true"; into your DropDownList

<asp:DropDownList ID="UploadLocation" runat="server" 
         AutoEventWireup="true" EnableViewState="true" AutoPostBack="true";>
 </asp:DropDownList>

Answer 4

Confirm that you page level ViewState is enabled
and also confirm that your databinding code is inside !IsPostback condition

if (!IsPostback)
{
.... databinding code..
}