Question

我有2个下拉列表，第一个是Country，第二个是City。

我尝试使用级联下拉列表进行搜索，并且当显示结果时，下拉列表的值不再为空。例如，我在Country中选择奥地利，在Vienna中选择City，结果显示时，在下拉Country中，该值仍为Austria和{{ 1}}是City。

我尝试使用javascript，但我不能。这是我的代码：

控制器

Vienna

视图模型

        [HttpGet]
        public ActionResult Customer()
        {
            List<Country> country = _CustomerService.GetCountryForDropDown();
            CustomerViewModel model = CustomerBuilder.BuildCountries(country);
            return View(model);
        }

        [HttpPost]
        public ActionResult Customer(CustemerRequest request, FormCollection frm)
        {
            if (ModelState.IsValid)
            {                
                List<Organization> ListOrganization = _CustomerService.GetOrganization(request.InfotechCode, request.CustomerName, frm["DDCountryModel"], frm["ddlCity"]);
                List<Country> country = _CustomerService.GetCountryForDropDown();
                cvm = CustomerBuilder.Build(ListOrganization,country);
                cvm.Request = request;
                return RedirectToAction("Result", new { Page = 1 });
            }
            return View(new CustomerViewModel { Request = request, ListCustomer = null });
        }

        [HttpGet]
        public ActionResult Result(int Page)
        {
            if (cvm != null)
            {
                return View("Customer", cvm);
            }
            else
                return RedirectToAction("Customer", new { Request = Request });
        }

        [HttpPost]
            public ActionResult GetCityByCountryForDropDown(int CountryID, FormCollection frm)
            {
                List<City> city = _CustomerService.GetCityForDropDown();
                ITTOS.ViewModel.Customer.CustomerViewModel model = ITTOS.ViewModel.Builder.CustomerBuilder.BuildCities(city);

                List<ITTOS.ViewModel.Customer.DDCity> getCityFromCountry = new List<ITTOS.ViewModel.Customer.DDCity>();
                getCityFromCountry = model.DDCityModel.Where(r => r.CountryID == CountryID).ToList();
                SelectList CityinCountry = new SelectList(getCityFromCountry, "CityID", "CityName", 0);
                return Json(CityinCountry);
            }

查看模型构建器

[Serializable]
    public class CustemerRequest
    {
        public string InfotechCode { get; set; }
        public string CustomerName { get; set; }
        public int? CountryID { get; set; }
        public int? CityID { get; set; }
    }

    public class DDCountry
    {
        public int CountryID { get; set; }
        public string CountryName { get; set; }
    }

    public class DDCity
    {
        public int CountryID { get; set; }
        public int CityID { get; set; }
        public string CityName { get; set; }
    }

和我的观点

public static CustomerViewModel BuildCities (List<City> city)
        {
            CustomerViewModel model = new CustomerViewModel();
            model.DDCityModel = new List<DDCity>();

            foreach (var cities in city)
            {
                DDCity ct = new DDCity
                {
                    CityID = cities.CityID,
                    CityName = cities.CityName,
                    CountryID = cities.CountryID
                };
                model.DDCityModel.Add(ct);
            }
            return model;
        }

        public static CustomerViewModel BuildCountries(List<Country> country)
        {
            CustomerViewModel model = new CustomerViewModel();
            model.DDCountryModel = new List<DDCountry>();

            foreach (var countries in country)
            {
                DDCountry ct = new DDCountry
                {
                    CountryID = countries.CountryID,
                    CountryName = countries.CountryName
                };
                model.DDCountryModel.Add(ct);
            }
            return model;
        }

请有人帮帮我，

Answer 1

这是一个相当简单的例子，希望它会对你有所帮助。根本不需要隐藏的领域。 _Adapter类代表我的数据库访问层的一部分（因为我使用EF＆amp; PostgreSQL），“公司”类基本上是数据表实体。

<强>型号：

public class CompanyModel {

    public CountryModel Country{ get; set; }

    public CityModel City { get; set; }

    public SelectList AvailableCountries {
        get {
            return new SelectList(
                CountryAdapter.GetCountries(),
                "Id",
                "Name"
                );
        }
    }

    public SelectList AvailableCities {
        get {
            return new SelectList(
                CityAdapter.GetCities(Country.Id),
                "Id",
                "Name"
                );
        }
    }

    public CompanyModel(Companies company) {// from the database layer
        Country = new CountryModel (company.CountryId, company.Countries.Name);
        City = new CityModel(company.CityId, company.Cities.Name);
}


public class CountryModel {

    public int Id { get; set; }

    public string Name { get; set; }

    public CountryModel() {
    }

    public CountryModel(int id, string name) {
        Id = id;
        Name = name;
    }
}


public class CityModel {

    public int Id { get; set; }

    public string Name { get; set; }

    public CityModel() {
    }

    public CityModel(int id, string name) {
        Id = id;
        Name = name;
    }

<强>控制器：

    [HttpGet]
    public ActionResult Edit(int id) {
        return View(new CompanyModel(CompanyAdapter.GetCompany(id)));
    }

    [HttpPost]
    public ActionResult Edit(CompanyModel company) {
        if (ModelState.IsValid)
           // save in the db

        return View(company);
    }

    /// <param name="id">CountryId</param>
    public ActionResult GetCities(int id) {
        //retrieve from db
        var cities = CityAdapter.GetCities(id)
            .Select(city => new { id = city.Id, name = city.Name })
            .ToList();

        return Json(cities, JsonRequestBehavior.AllowGet);
    }

查看：

@model ServbitOffice.Models.CompanyModel @using (Html.BeginForm()) { @Html.DropDownListFor(company => company.Country.Id, Model.AvailableCountries, new { onchange = "LoadCities()" }) @Html.DropDownListFor(company => company.City.Id, Model.AvailableCities) <input type="submit" value="Save"/> }

脚本（也在上一个视图中）：

<script type="text/javascript"> function LoadCities() { var selectedCountryId= $("#Country_Id").val(); $.ajax({ url: "@Url.Action("GetCities")", type: 'GET', data: { id: selectedCountryId}, }).done(function (result) { var cities = $('#City_Id'); cities.empty(); $.each(result, function (index, item) { cities.append( $('<option />', { value: item.id, text: item.name }) ); }); }); }; </script>

如何使用隐藏设置级联下拉列表中的选定值

1 个答案: