下拉菜单的选定索引与显示的选定元素的位置不匹配

Question

I have a dropdown list and an add button. When the add button is clicked, the selected item from the dropdown is supposed to be added to a database. However the selectedIndex value used in the function called by the add button is wrong. It doesn't match the actual index of the currently selected item (most of the time.)

Here is the dropdown and the button:

<asp:DropDownList runat="server" id="ddlNewCreature" AutoPostBack = "false" DataMember="0"></asp:DropDownList>

<asp:Button ID="btnAddCreature" runat="server" Text="Add" onClick="AddCreature"/>

Here is the code behind:

protected void Page_Load(object sender, EventArgs e)
{                     
    if (!IsPostBack)
    {
    if (ddParent1.Items.Count == 0)
    {
        if (ddBaby.Items.Count == 0)
        {
        loadCreatureLists(true, true);
        }
        else
        {
        loadCreatureLists(true, false);
        }
    }
    else
    {
        if (ddBaby.Items.Count == 0)
        {
        loadCreatureLists(false, true);
        }
    }
    }
}


protected void loadCreatureLists(Boolean loadParents, Boolean loadOffspring )
{
    SqlConnection conn = new SqlConnection(WebConfigurationManager.ConnectionStrings["Drin"].ConnectionString);
    string sSql = "select creature, element1, element2 from dbo.tinycastlecreatures order by creature";
    SqlCommand cmd = new SqlCommand(sSql, conn);
    SqlDataReader reader;

    try
    {
    conn.Open();
    reader = cmd.ExecuteReader();
    while (reader.Read())
    {
        ListItem newItem = new ListItem();
        newItem.Text = reader["creature"].ToString();
        newItem.Value = normalizeElementOrder(reader["element1"].ToString(),reader["element2"].ToString());
        if (loadParents && !chkMine.Checked)
        {

        ddParent1.Items.Add(newItem);
        ddParent2.Items.Add(newItem);
        }
        if (loadOffspring)
        {
        ddBaby.Items.Add(newItem);
        ddlNewCreature.Items.Add(newItem);
        }
    }
    reader.Close();
    }
    catch (Exception err) { }
    finally { if (!loadParents || !chkMine.Checked) { conn.Close(); } }
}

protected void AddCreature(object sender, EventArgs e)
{
    int indx = ddlNewCreature.SelectedIndex;
    string sCreature = ddlNewCreature.Items[indx].Text.ToString();
    for (int i = 0; i < ddlNewCreature.Items.Count; i++ )
    {
    sCreature = ddlNewCreature.Items[i].Text.ToString();
    }
    ddlNewCreature.SelectedIndex = 0;
    SqlConnection conn = new SqlConnection(WebConfigurationManager.ConnectionStrings["Drin"].ConnectionString);
    conn.Open();
    string sSql = "[dbo].[tinycastle_add_user_creature] '";
    sSql += sCreature;
    sSql += "','deb'"; 
    SqlCommand cmd = new SqlCommand(sSql, conn);
    cmd.ExecuteNonQuery();
    sCreature = ddlNewCreature.Items[indx].Text.ToString();
    sqlMineSource.DataBind();
    gridMine.DataBind();
}

Answer 1

B.Yaylaci's suggestion on checking the SelectedIndex in the dropdown's changed event is on the right track to find out why (when? :)) the index isn't matching up with what you expect, I think. Also, it'd be much easier (and more-accurate) to use the SelectedValue property if all you need is the text in the dropdown. https://stackoverflow.com/a/4399747

Answer 2

I circumvented the problem by ripping out the way the various drop down lists were populated, and binding them to a SQLDataStore instead. I don't know why that helped, but it did.

Answer 3

Use ddlNewCreature.SelectedValue this will fix your problem." SelectedValue " give you the correct index value for the selected DropDownList. This worked for me.