ASP.NET和C＃-在静态DropDownList中获取所选项目

Question

I'm new to ASP.NET and I'm having problem with getting selected item in static DropDownList. This is the structure of my list:

                   <asp:DropDownList ID="txtGender" runat="server">
                            <asp:ListItem>Male</asp:ListItem>

                            <asp:ListItem>Female</asp:ListItem>

                            <asp:ListItem>Other</asp:ListItem>

                            <asp:ListItem>Rather not say</asp:ListItem>
                    </asp:DropDownList>

Then in the code where I want to get the selected item, I use txtGender.SelectedItem and always get the first item as input. I have another DropDownList where I have to fetch the items from database, then I use IsPostBack before calling DataBind() and it works fine. So I'm wondering how should I use IsPostBack in static DropDownList as above? Please help.

* EDITED

Below is the method that I use the txtGender :

protected void btnSave_Click(object sender, EventArgs e)
{
    int uID= int.Parse(Session["uID"].ToString());
    PhotoDataSetTableAdapters.MembersTableAdapter memAdap = new PhotoDataSetTableAdapters.MembersTableAdapter();
    PhotoDataSet.MembersDataTable memTable = memAdap.GetMemberByID(uID);

    DataRow[] dr = memTable.Select("userID = " + uID);
    string Fname = memTable.AsEnumerable().Single().Field<String>("avatar");
    if(PhotoUploader.HasFile)
    {
       Fname = Path.GetFileName(PhotoUploader.FileName);
       PhotoUploader.SaveAs(Server.MapPath("~/avatar/") + Fname);
    }

    string newPass = memTable.AsEnumerable().Single().Field<String>("password");
    if (txtPass.Text != "")
    {
        newPass = txtPass.Text;
    }

    string tmp = txtBday.Text;
    DateTime bday = DateTime.ParseExact(tmp, "dd/MM/yyyy", null);

    memAdap.UpdateMemberProfile(newPass, txtEmail.Text, txtRealname.Text, txtLocation.Text, txtGender.SelectedItem.Text, txtBio.Text, bday, Fname, uID);
    //Response.Write(txtGender.SelectedItem.Text + " " + txtBio.Text);
    Response.Redirect("Photostream.aspx");
}

Ps: I tried using Response.Write to see the input for gender but it's always the first item of the list to be selected. I also have no input for txtBio even though everything seems alright.

Answer 1

If you are not rebinding the options for the drop down and you are not resetting its actual value on post back, you should not have to do anything with IsPostBack . You should just be able to do the following to get the value and text:

string value = txtGender.SelectedValue;
string text = txtGender.SelectedItem.Text;

Note: the actual value of a control will not be available during Page_Init since the page has not been completely initialized yet.

Answer 2

You need to assign unique values to the ListItems in your DropDownList:

<asp:DropDownList ID="txtGender" runat="server">
      <asp:ListItem Value="0">Male</asp:ListItem>

      <asp:ListItem Value="1">Female</asp:ListItem>

      <asp:ListItem Value="2">Other</asp:ListItem>

      <asp:ListItem Value="3">Rather not say</asp:ListItem>
</asp:DropDownList>

Try this and see if it helps.

Answer 3

Bind the dropdown on page load and check the IsPostBack property

protected void Page_Load(object sender, EventArgs e)
{
   if (!IsPostBack)
    {
        // Dropdown binding code goes here....   
    }
 }