无刷新下拉框联动方法：

 

Controllers代码

public JsonResult DH_Change(string DH_ID)        {            List
     
       TeamLeaderList = FinanceDB.Get_TeamLeaderList(DH_ID);            return Json(TeamLeaderList);        }        public JsonResult TL_Change(string TL_ID)        {            List
      
        SalesList = FinanceDB.Get_SalesList(TL_ID);            return Json(SalesList);        }
      
     

 

后台获取并返回List<SeleceListItem>

public List
     
       Get_TeamLeaderList(string DH_ID)        {            List
      
        list = new List
       
        ();            list.Add(new SelectListItem { Value = "", Text = "All" });            string str = "SELECT distinct child_Staff_ID, child_name ";            str += "FROM VW_CASH_SLX_USER_TREE t inner join SYN_SLX_USERINFO u ";            str += "ON t.child_Staff_ID = u.cash_staff_id ";            str += "INNER JOIN dbo.SYN_SLX_USERSECURITY su on u.userid = su.userid ";            str += "where su.ISMANAGER = 'T' and ISNULL(child_staff_id, '') <> '' ";            if (string.IsNullOrEmpty(DH_ID))            {                str += "and t.Root_Staff_ID in (select parm_value from parm_tbl where parm_group = 'SALES_DEPT_HEADER') order by child_name";            }            else            {                str += "and t.Root_Staff_ID in ('" + DH_ID + "') order by child_name";            }            try            {                using (SqlConnection conn = new SqlConnection(connstr))                {                    if (conn.State == ConnectionState.Closed)                    {                        conn.Open();                    }                    SqlCommand cmd = conn.CreateCommand();                    cmd.CommandText = str;                    cmd.CommandType = CommandType.Text;                    SqlDataReader objDR = cmd.ExecuteReader();                    while (objDR.Read())                    {                        string select_text = objDR["child_name"].ToString();                        string select_value = objDR["child_Staff_ID"].ToString();                                                list.Add(new SelectListItem { Value = select_value, Text = select_text });                    }                    cmd.Dispose();                }            }            catch (Exception e)            {                throw e;            }            return list;        }public List
        
          Get_SalesList(string TL_ID)        {            List
         
           list = new List
          
           (); list.Add(new SelectListItem { Value = "", Text = "All" }); string str = "SELECT distinct child_Staff_ID, child_name "; str += "FROM VW_CASH_SLX_USER_TREE t "; str += "where ISNULL(child_staff_id, '') <> '' and "; str += "t.Root_Staff_ID in ( "; if (string.IsNullOrEmpty(TL_ID)) { str += "select parm_value from parm_tbl where parm_group = 'SALES_DEPT_HEADER' ) order by child_name "; } else { str += "'" + TL_ID + "') order by child_name"; } try { using (SqlConnection conn = new SqlConnection(connstr)) { if (conn.State == ConnectionState.Closed) { conn.Open(); } SqlCommand cmd = conn.CreateCommand(); cmd.CommandText = str; cmd.CommandType = CommandType.Text; SqlDataReader objDR = cmd.ExecuteReader(); while (objDR.Read()) { string select_text = objDR["child_name"].ToString(); string select_value = objDR["child_Staff_ID"].ToString(); list.Add(new SelectListItem { Value = select_value, Text = select_text }); } cmd.Dispose(); } } catch (Exception e) { throw e; } return list; }
          
         
        
       
      
     

 

Ajax 动态更新

// Report sales change.function DH_onChange() {    var dh_id = $("#salesdephead_report").val();    $.ajax({        type: 'get',        url: '/Reports.mvc/DH_Change/',        data: { DH_ID: dh_id },        contentType: 'application/json;charset=uft-8',        dataType: 'json',        success: function(data) {        var selectlist =data;        $("#teamleader_report").empty();        for(i=0;i
     
      "+data[i].Text+"");        }        },        error: function() {            alert("faile to request data");        }    });    TL_onChange(dh_id);}function TL_onChange(DH_ID) {    var tl_id;    if (DH_ID != null && DH_ID != "")        tl_id = $("#salesdephead_report").val();    else        tl_id = $("#teamleader_report").val();    $.ajax({        type: 'post',        url: '/Reports.mvc/TL_Change/',        data: { TL_ID: tl_id },        dataType: 'json',        success: function(data) {        var selectlist = data;        $("#requester_report").empty();        for (i = 0; i < selectlist.length; i++) {            $("#requester_report").append("
      " + data[i].Text + "");        }        },        error: function() {            alert("faile to request data");        }    })}//
     

 

前台HTML代码

Sales Department Head
销售部门审批人:       <%=Html.DropDownList("salesdephead_report", null, new { @style = "width:125px;", onchange = "DH_onChange()" })%>Team Leader
团队组长:             <%=Html.DropDownList("teamleader_report", null, new { @style = "width:125px;", onchange = "TL_onChange('')" })%>

 

但是我们都知道，JQuery默认是异步执行的，所谓异步就是在ajax提交的过程当中，程序已经在执行下面的代码，两者是同时在进行的。有时候，我们却不希望ajax异步执行，而是想要等ajax返回数据后再作操作，那就需要做一点点的小改动。

Jquery的ajax还有async这么一个控制同步或者异步的属性。

再ajax中添加“ async：false, ”， 就会变成是同步执行了，也就是再ajax返回数据后才继续下面的代码。

其实除了修改属性async的方法外，还能通过传入一个函数解决问题。

以上，是今天所用到得一点知识，希望记录下有帮助到人啦。