MVC 3 Razor视图中的级联下拉

Question

我对如何在Razor视图中为地址实现级联下拉列表感兴趣.我的网站实体有一个SuburbId属性.郊区有CityId,City有ProvinceId.我想在"站点"视图中显示所有郊区,城市和省的下拉列表,例如,郊区下拉列表将首先显示"首先选择一个城市",以及城市下拉列表,"首先选择一个省".在选择省份时,省内的城市居住等.

我怎样才能做到这一点？我从哪里开始？

Answer 1

让我们用一个例子来说明.一如既往地从模型开始:

public class MyViewModel
{
    public string SelectedProvinceId { get; set; }
    public string SelectedCityId { get; set; }
    public string SelectedSuburbId { get; set; }
    public IEnumerable<Province> Provinces { get; set; }
}

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

接下来是控制器:

public class HomeController : Controller
{
    public ActionResult Index()
    {
        var model = new MyViewModel
        {
            // TODO: Fetch those from your repository
            Provinces = Enumerable.Range(1, 10).Select(x => new Province
            {
                Id = (x + 1).ToString(),
                Name = "Province " + x
            })
        };
        return View(model);
    }

    public ActionResult Suburbs(int cityId)
    {
        // TODO: Fetch the suburbs from your repository based on the cityId
        var suburbs = Enumerable.Range(1, 5).Select(x => new
        {
            Id = x,
            Name = "suburb " + x
        });
        return Json(suburbs, JsonRequestBehavior.AllowGet);
    }

    public ActionResult Cities(int provinceId)
    {
        // TODO: Fetch the cities from your repository based on the provinceId
        var cities = Enumerable.Range(1, 5).Select(x => new
        {
            Id = x,
            Name = "city " + x
        });
        return Json(cities, JsonRequestBehavior.AllowGet);
    }
}

最后一个观点:

@model SomeNs.Models.MyViewModel

@{
    ViewBag.Title = "Home Page";
}

<script type="text/javascript" src="/scripts/jquery-1.4.4.js"></script>
<script type="text/javascript">
    $(function () {
        $('#SelectedProvinceId').change(function () {
            var selectedProvinceId = $(this).val();
            $.getJSON('@Url.Action("Cities")', { provinceId: selectedProvinceId }, function (cities) {
                var citiesSelect = $('#SelectedCityId');
                citiesSelect.empty();
                $.each(cities, function (index, city) {
                    citiesSelect.append(
                        $('<option/>')
                            .attr('value', city.Id)
                            .text(city.Name)
                    );
                });
            });
        });

        $('#SelectedCityId').change(function () {
            var selectedCityId = $(this).val();
            $.getJSON('@Url.Action("Suburbs")', { cityId: selectedCityId }, function (suburbs) {
                var suburbsSelect = $('#SelectedSuburbId');
                suburbsSelect.empty();
                $.each(suburbs, function (index, suburb) {
                    suburbsSelect.append(
                        $('<option/>')
                            .attr('value', suburb.Id)
                            .text(suburb.Name)
                    );
                });
            });
        });
    });
</script>

<div>
    Province: 
    @Html.DropDownListFor(x => x.SelectedProvinceId, new SelectList(Model.Provinces, "Id", "Name"))
</div>
<div>
    City: 
    @Html.DropDownListFor(x => x.SelectedCityId, Enumerable.Empty<SelectListItem>())
</div>
<div>
    Suburb: 
    @Html.DropDownListFor(x => x.SelectedSuburbId, Enumerable.Empty<SelectListItem>())
</div>

作为改进,可以通过编写jquery插件来缩短javascript代码,以避免重复某些部分.

更新:

谈论插件你可以在行中找到一些东西:

(function ($) {
    $.fn.cascade = function (options) {
        var defaults = { };
        var opts = $.extend(defaults, options);

        return this.each(function () {
            $(this).change(function () {
                var selectedValue = $(this).val();
                var params = { };
                params[opts.paramName] = selectedValue;
                $.getJSON(opts.url, params, function (items) {
                    opts.childSelect.empty();
                    $.each(items, function (index, item) {
                        opts.childSelect.append(
                            $('<option/>')
                                .attr('value', item.Id)
                                .text(item.Name)
                        );
                    });
                });
            });
        });
    };
})(jQuery);

然后简单地将其连线:

$(function () {
    $('#SelectedProvinceId').cascade({
        url: '@Url.Action("Cities")',
        paramName: 'provinceId',
        childSelect: $('#SelectedCityId')
    });

    $('#SelectedCityId').cascade({
        url: '@Url.Action("Suburbs")',
        paramName: 'cityId',
        childSelect: $('#SelectedSuburbId')
    });
});

Answer 2

感谢Darin领导解决方案.这对我来说非常有帮助.但正如'xxviktor'提到的那样,我确实得到了循环引用.错误.为了摆脱它,我已经这样做了.

    public string GetCounties(int countryID)
    {
        List<County> objCounties = new List<County>();
        var objResp = _mastRepo.GetCounties(countryID, ref objCounties);
        var objRetC = from c in objCounties
                      select new SelectListItem
                      {
                          Text = c.Name,
                          Value = c.ID.ToString()
                      };
        return new JavaScriptSerializer().Serialize(objRetC);
    }

为了实现自动级联,我通过这种方式略微扩展了jQuery扩展.

        $('#ddlCountry').cascade({
            url: '@Url.Action("GetCounties")',
            paramName: 'countryID',
            childSelect: $('#ddlState'),
            childCascade: true
        });

实际的JS使用如下所示的参数(在JSON请求中).

                // trigger child change
                if (opts.childCascade) {
                    opts.childSelect.change();
                }

希望这可以帮助有类似问题的人.