MVC4中使用Html.DropDownList实现级联

本文记录了一个在MVC4中使用PartialView实现级联效果的小例子。

准备工作

首先准备一下要级联的数据，新建两个类：Province和City

    public class Province
    {
        public string Id { get; set; }

        public string Name { get; set; }
    }

    public class City
    {
        public string Id { get; set; }

        public string Name { get; set; }

        public string Province { get; set; }
    }

并在Controller中准备好数据，

        List<Province> provinceList = new List<Province>();
        List<City> cityList = new List<City>();

        private void InitData()
        {
            provinceList.Add(new Province { Id = "", Name = "河北省" });
            provinceList.Add(new Province { Id = "", Name = "河南省" });
            provinceList.Add(new Province { Id = "", Name = "广东省" });

            cityList.Add(new City { Id = "", Name = "石家庄", Province = "" });
            cityList.Add(new City { Id = "", Name = "邢台", Province = "" });
            cityList.Add(new City { Id = "", Name = "保定", Province = "" });

            cityList.Add(new City { Id = "", Name = "郑州", Province = "" });
            cityList.Add(new City { Id = "", Name = "安阳", Province = "" });
            cityList.Add(new City { Id = "", Name = "洛阳", Province = "" });

            cityList.Add(new City { Id = "", Name = "广州", Province = "" });
            cityList.Add(new City { Id = "", Name = "中山", Province = "" });
            cityList.Add(new City { Id = "", Name = "佛山", Province = "" });
        }

Controller

在控制器中创建一个返回分步视图的Action，在前台第一级调用的时候触发这个action，返回第二级需要的数据。

        public ActionResult ShowCity(string provinceId)
        {
            InitData();
            var result = cityList.Where(city => city.Province == provinceId);
            ViewBag.City = result;
            return PartialView("PartialCity");
        }

View

先创建一个PartialView：PartialCity.cshtml，如下：

@{
    ViewBag.Title = "PartialCity";
}

城市: @Html.DropDownList("city_dropdownlist", new SelectList(ViewBag.City, "Id", "Name"))

在主View中的使用这个PartialView，

    <div id="province">
        省份: @Html.DropDownList("province_dropdownlist", new SelectList(ViewBag.Province, "Id", "Name"))
    </div>
    <div id="city">
        @Html.Partial("PartialCity")
    </div>

最后，需要在主View页面写几行js代码，给第一级dropdownlist注册一个change事件，并且在事件触发的时候调用刚刚创建的ShowCity方法

@Scripts.Render("~/Scripts/jquery-1.7.1.min.js");
<script type="text/javascript">
    $(document).ready(init);

    function init() {
        $("select[name='province_dropdownlist']").change(function () {
            var selectedProvince = $(this).val();
            ShowCityWithSelectedProvince(selectedProvince);
        });
    }

    function ShowCityWithSelectedProvince(province) {
        $.ajax({
            url: "@Url.Action("ShowCity", "Home")",
            data: { provinceId: province },
            success: function (data) {
                $("#city").html(data);
            }
        });
    }

这样，就实现了级联效果。

以上