联动下拉框 jquery 插件（一）

CascadingDropDown是jquery联动下拉框插件，可以用于asp.net,或者mvc3,采用ajax，返回json数据。

<asp:DropDownList ID="ddlRegion" runat="server"></asp:DropDownList>
<asp:DropDownList ID="ddlProvince" runat="server"></asp:DropDownList>
<asp:DropDownList ID="ddlCity" runat="server"></asp:DropDownList>

<script src="Scripts/jquery-1.6.1.min.js" type="text/javascript"></script>
<script src="Scripts/jquery.cascadingDropDown.js" type="text/javascript"></script>

当第一个列表中选择后，第二个列表自动填充

$("#ddlProvince").CascadingDropDown("#ddlRegion", 'Controls/AreaHandler.ashx', { textfield: 'ProvinceName', valuefiled: 'ProvinceId' });
$("#ddlCity").CascadingDropDown("#ddlProvince", 'Controls/AreaHandler.ashx', { textfield: 'CityName', valuefiled: 'CityId' });

JSON：
{"count":"7","error":"","success":"true","data":[
{"ProvinceId":"14","ProvinceName":"江西省"},
{"ProvinceId":"16","ProvinceName":"河南省"},
{"ProvinceId":"17","ProvinceName":"湖北省"},
{"ProvinceId":"21","ProvinceName":"广西壮族自治区"}]
}


详细：

$(targetID).CascadingDropDown(sourceID, actionPath, settings)

• targetID
  即将自动填充选择列表的ID.
• sourceID
  change事件的下拉框ID（即父控件ID）.
• actionPath
  post数据的URL

参数：

• promptText
  下拉框第一个选项
  默认: -- 请选择 --
• loadingText
  当加载时.
  默认:加载中..
• errorText
  出错时
  默认: 加载失败.
• postData
  post完成后的数据
  如:
  postData: function () {
      return { prefix: $('#txtPrefix').val(), customerID: $('#customerID').val() };
  }
  将会 prefix=foo&customerID=bar 方式传参.
  默认: 以序列化 serialize 一定要有控件的name属性 不然无法序列化

• onLoading (event)
  正在加载……
• onLoaded (event)
  加载完成后……
  
  textfield：对应数据库 值 字段
  valuefiled：对应数据库 id 字段
  默认：

  textfield: 'text',
  valuefiled: 'value'

后台处理数据：

if (context.Request.Params["ddlProvince"] != null)
{
 sql = String.Format("SELECT  CityId, CityName FROM T_City where ProvinceId='{0}'", context.Request.Params["ddlProvince"]);
}

if (context.Request.Params["ddlRegion"] != null)
sql = String.Format("SELECT ProvinceId,ProvinceName FROM T_Province where RegionId='{0}'", context.Request.Params["ddlRegion"]);

jquery.cascadingDropDown.js

(function ($) {
 $.fn.CascadingDropDown = function (source, actionPath, settings) {
     if (typeof source === 'undefined') {throw "?????"; }
     if (typeof actionPath == 'undefined') { throw "?????"; }
     var optionTag = '<option></option>';
     var config = $.extend({}, $.fn.CascadingDropDown.defaults, settings);
     return this.each(function () {
     var $this = $(this);
     (function () {
         var methods = {
             clearItems: function () {
                 $this.empty();
                 if (!$this.attr("disabled")) {
                     $this.attr("disabled", "disabled");
                 }
             },
             reset: function () {
                 methods.clearItems();
                 $this.append($(optionTag).attr("value", "").text(config.promptText));
                 $this.trigger('change');
             },
             initialize: function () {
                 if ($this.children().size() == 0) {
                     methods.reset();
                 }
             },
             showLoading: function () {
                 methods.clearItems();
                 $this.append($(optionTag).attr("value", "").text(config.loadingText));
             },
             loaded: function () {
                 $this.removeAttr("disabled");
                 $this.trigger('change');
             },
             showError: function () {
                 methods.clearItems();
                 $this.append($(optionTag).attr("value", "").text(config.errorText));
             },
             post: function () {
                 methods.showLoading();
                 $.isFunction(config.onLoading) && config.onLoading.call($this);
                 $.ajax({
                     url: actionPath,
                     type: 'POST',
                     dataType: 'json',
                     data: ((typeof config.postData == "function") ? config.postData() : config.postData) || $(source).serialize(),
                     success: function (data) {
                         methods.reset();
                         $.each(data.data, function (i, k) {
                             $this.append($(optionTag).attr("value", eval("k." + config.valuefiled)).text(eval("k." + config.textfield)));
                         });
                         methods.loaded();
                         $.isFunction(config.onLoaded) && config.onLoaded.call($this);
                     },
                     error: function () {
                         methods.showError();
                     }
                 });
             }
         };
 
        $(source).change(function () {
             var parentSelect = $(source);
             if (parentSelect.val() != '') {
                 methods.post();
             }
             else {
                 methods.reset();
             }
         });
         methods.initialize();
     })();
     });
 }
 
$.fn.CascadingDropDown.defaults = {
     promptText: '-- ??? --',
     loadingText: '??????',
     errorText: '????',
     postData: null,
     onLoading: null,
     onLoaded: null,
     textfield: 'text',
     valuefiled: 'value'
 }
 })(jQuery);