Cascading Dropdown Edit Mode

district.cs

  protected void Edit(object sender, EventArgs e)
        {
            hfAddEditId.Value = (sender as Button).CommandArgument;
            _HrmEntity.intDistrictId = Convert.ToInt32(hfAddEditId.Value);
            List<Entity_HRM> listdist = new List<Entity_HRM>();
            listdist = _district.GetAllDataById(_HrmEntity);
            var sta = (from usr in listdist select usr);
            if (sta.Any())
            {
                List<Entity_HRM> listCountry = new List<Entity_HRM>();
                listCountry = _country.GetAll();
                var con = (from usr in listCountry select usr);
                if (con.Any())
                {
                    ddlCountry.DataSource = _country.GetAll();
                    ddlCountry.DataTextField = "varCountryName";
                    ddlCountry.DataValueField = "intCountryId";
                    ddlCountry.DataBind();
                    ddlCountry.Items.Insert(0, new ListItem("--- Select Country ---", ""));
                    ddlCountry.SelectedIndex = Convert.ToInt32(sta.Single().intCountryId.ToString());
                }

                List<Entity_HRM> listState = new List<Entity_HRM>();
                listState = _country.GetAll();
                var st = (from usr in listCountry select usr);
                if (con.Any())
                {
                    _HrmEntity.intCountryId = Convert.ToInt32(sta.Single().intCountryId.ToString());
                    ddlState.DataSource = _state.GetAllDataByCountryId(_HrmEntity);
                    ddlState.DataTextField = "varStateName";
                    ddlState.DataValueField = "intStateId";
                    ddlState.DataBind();
                    ddlState.SelectedValue = sta.Single().intStateId.ToString();
                    ddlState.Items.Insert(0, new ListItem("--- Select State ---", ""));
                }

                txtDistrict.Text = sta.Single().varDistrict;
                System.Text.StringBuilder sb = new System.Text.StringBuilder();
                sb.Append(@"<script type='text/javascript'>");
                sb.Append("$('#AddUpdateModal').modal('show');");
                sb.Append(@"</script>");
                ScriptManager.RegisterClientScriptBlock(this, this.GetType(), "AddUpdateModalScript", sb.ToString(), false);
                btnSave.Visible = false;
                btnUpdate.Visible = true;
                lblHeading.Text = "Update Details";
            }
       }