Question

我用另一个DDL填充DDL，我从另一个页面获取值

 protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            DropDownList1.DataSource = ProfileMasterDAL.bindcountry();
            DropDownList1.DataBind();
            DropDownList1.Items.Insert(0, "--Select country--");

        }


        if(Session["uname"]!=null)
        {
              DropDownList1.SelectedValue = Session["country"].ToString();
           ProfileMasterBLL bll=new ProfileMasterBLL();
            foreach (var VARIABLE in ProfileMasterDAL.bindcountry())
            {
                if (VARIABLE.ToString().Contains(DropDownList1.SelectedItem.Text))
                {
                    var query = (ProfileMasterDAL.GetStatesByCountrys(DropDownList1.SelectedItem.Text));
                    DropDownList2.DataSource = query;
                    DropDownList2.DataBind();
                 }
            }


            TextBox8.Text = Session["email"].ToString();
            string pwd = Session["pwd"].ToString();
            TextBox9.Attributes.Add("value",pwd);
            TextBox10.Attributes.Add("value", pwd);

        }
    }

但问题是每当我更改DDL值固定为会话值时，因为它在page_load中，所以如何将值更改为DDL中的选定项目。

Answer 1

使用OnSelectedIndexChanged event以及为下拉列表将AutoPostBack property设置为true。

在OnSelectedIndexChanged事件处理程序中，添加代码以填充第二个下拉列表。

Answer 2

如果已经理解了问题的正确性，那么您想要更改DropDownList2的值根据DropDownList1的值，下拉列表的初始值来自另一个页面

    protected void Page_Load(object sender, EventArgs e)
     {
        if (!IsPostBack)
        {
            DropDownList1.DataSource = ProfileMasterDAL.bindcountry();
            DropDownList1.DataBind();
            DropDownList1.Items.Insert(0, "--Select country--");

            //get the selected country from another page
            string selectedCountry = Convert.ToString(Session["country"]);

            //set the selected value
            DropDownList1.Items.FindByValue(selectedCountry).Selected = true;

            //Bind Dropdonwlist2
             BindDropDownList(DropDownList1.SelectedItem.Text);

        }

        /*
         remaining code
         */
    }

绑定dropdonwList 2代码

    /// <summary>
    /// Bind dropdownlist2 
    /// </summary>
    /// <param name="selectedCountry"></param>
    protected void BindDropDownList(string selectedCountry)
    {
        ProfileMasterBLL bll = new ProfileMasterBLL();
        foreach (var VARIABLE in ProfileMasterDAL.bindcountry())
        {
            if (VARIABLE.ToString().Contains(selectedCountry))
            {
                var query = (ProfileMasterDAL.GetStatesByCountrys(selectedCountry));
                DropDownList2.DataSource = query;
                DropDownList2.DataBind();
            }
        }

    }

关于dropdonwlist1的选定索引更改，现在值将更改

为dropdownlist1设置autopostback为true

DropDownList1.AutoPostBack = true;

    /// <summary>
    /// DropDownList1 Selcted Index change
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    protected  void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
         BindDropDownList(DropDownList1.SelectedItem.Text);
    }

希望这能解决你的问题

Answer 3

    protected void Page_Load(object sender, EventArgs e)
     {
        if (!IsPostBack)
        {
            DropDownList1.DataSource = ProfileMasterDAL.bindcountry();
            DropDownList1.DataBind();
            DropDownList1.Items.Insert(0, "--Select country--");

            if(Session["uname"]!=null)
            {
                DropDownList1.SelectedValue = Session["country"].ToString();
                BindList()
            }

        }
        if(Session["uname"]!=null)
        {
            TextBox8.Text = Session["email"].ToString();
            string pwd = Session["pwd"].ToString();
            TextBox9.Attributes.Add("value",pwd);
            TextBox10.Attributes.Add("value", pwd);     
        }
     }

添加绑定ddl2的方法

private void BindList()
{
    ProfileMasterBLL bll=new ProfileMasterBLL();
    foreach (var VARIABLE in ProfileMasterDAL.bindcountry())
    {
      if (VARIABLE.ToString().Contains(DropDownList1.SelectedItem.Text))
      {
         var query = 
       ProfileMasterDAL.GetStatesByCountrys(DropDownList1.SelectedItem.Text));
                    DropDownList2.DataSource = query;
                    DropDownList2.DataBind();
      }
}

为dropdownlist1设置autopostback true，并添加selectedIndexChanged

protected  void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
         BindList();
    }

更改下拉列表选定的值

3 个答案: