如何抵抗下拉值. [英] How to resist the drop down value.

问题描述

我有一个下拉列表和2个列表框.我希望我无法从列表框1和2中选择任何内容，直到我没有从dropdownlist中选择任何内容，但是每次我从dropdownlist中选择任何内容时，它都会回发并且其值不能抵抗.

I have a drop downlist and 2 list box . I want that i am not able to select anything from listbox 1 and 2 until i am not selecting the item from dropdownlist but every time i select anything from dropdownlist it postback and its value is not resisting .

<div>
    <asp:DropDownList ID="ddlAdmin" runat="server" >
    <table width="70%">
    <tr><td colspan="3">
    <asp:ListBox ID="ProductListBox" runat="server" SelectionMode="Multiple" ></td>
    <td><asp:Button ID="BtnMoveLeft" runat="server" Text="Add Permission" OnClick="BtnMoveleft_Click" /></td>
    <td>
    
    <asp:ListBox ID="PermissionListBox" runat="server" SelectionMode="Multiple" ></td>
    </tr>
   </table>
    </div>

protected void Page_Load(object sender, EventArgs e)
    {
        FillProductList();
        FillAdminDropDownList();
    }

    protected void FillAdminDropDownList()
    {
        DataManager myData = new DataManager(DbFunctions.GetConnectionString());
        MySqlConnection myPConn = myData.GetPooledConnection(new MySqlConnection());


        MySqlCommand cmd = new MySqlCommand("SELECT adminuserid,adminusername FROM adminusermast", myPConn);
        DataTable dt = new DataTable();
        myPConn.Open();
        MySqlDataAdapter adptr = new MySqlDataAdapter(cmd);
        adptr.Fill(dt);
        myPConn.Close();
        if (dt.Rows.Count > 0)
        {
            ddlAdmin.Items.Clear();
            ddlAdmin.Items.Add("SELECT");
            foreach (DataRow drow in dt.Rows)
            {
                ListItem lst = new ListItem();
                lst.Value = drow[1].ToString();
                lst.Text = drow[0].ToString();
                ddlAdmin.Items.Add(lst);
            }
        }
    }
    protected void FillProductList()
    {
            DataManager myData = new DataManager(DbFunctions.GetConnectionString());
            MySqlConnection myPConn = myData.GetPooledConnection(new MySqlConnection());
            MySqlCommand com = new MySqlCommand("Select productid,productname from productmast", myPConn);
            MySqlDataReader Reader = null;
            myPConn.Open();
           Reader = com.ExecuteReader();
           while (Reader.Read())
           {

               ListItem newItem = new ListItem();
               newItem.Text = Reader["productname"].ToString();
               newItem.Value = Reader["productid"].ToString();
               ProductListBox.Items.Add(newItem);
           }
           Reader.Close();
       myPConn.Close();
    }

    protected void BtnMoveleft_Click(object sender, EventArgs e)
    {
        for (int i = ProductListBox.Items.Count - 1; i >= 0; i--)
        {
            if (ProductListBox.Items[i].Selected == true)
            {
                PermissionListBox.Items.Add(ProductListBox.Items[i]);
                ListItem li = ProductListBox.Items[i];
                ProductListBox.Items.Remove(li);
            }
        }
    }

推荐答案

最初设置DropDownList.Enabled ="false"

在DropDownList2_SelectedIndexChanged
中 {
DropDownList1.Enabled ="true";
}

initially set DropDownList.Enabled="false"

in the DropDownList2_SelectedIndexChanged
{
DropDownList1.Enabled="true";
}

如果可能将您的下拉列表放在更新面板"中.....

Hi ,
If Possibly Put Your dropdownlist in Update Panel.....

这篇关于如何抵抗下拉值.的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！