通用的下拉聯動封裝(級聯)

前言

平時工作中下拉聯動是相對比較麻煩的地方，雖然邏輯簡單，但是需要寫一堆js跟ajax請求。現在打算在.net core  mvc下封裝一個下拉聯動組件方便使用。

下面將實現一個 國家 語言 省市區 的多級聯動

 

創建實體模型

  1     public class UserModel  2  {  3         /// <summary>
        /// 用戶名  5         /// </summary>
        public string UserName { get; set; }  7 

        /// <summary>
        /// 國家 11         /// </summary>
        public int CountryId { get; set; } 13 
        /// <summary>
        /// 語言 16         /// </summary>
        public int LanguageId { get; set; } 18 
        /// <summary>
        ///省 21         /// </summary>
        public int PronviceId { get; set; } 23 
        /// <summary>
        /// 市 26         /// </summary>
        public int CityId { get; set; } 28 
        /// <summary>
        /// 區 31         /// </summary>
        public int GetDistrictId { get; set; } 33 
 } 35 
    public class Area 37  { 38         public int Id { get; set; } 39 
        public string Name { get; set; } 41 
        public int? ParentId { get; set; } 43  } 44 
    public class Language 46  { 47         public int Id { get; set; } 48 
        public int CountryId { get; set; } 50 
        public string Name { get; set; } 52     }

 

寫出對應下拉的Action方法

這里  下拉contorler名稱約定為DropdownListController,Action名稱約定為  Get +字段名的方式,參數名稱約定使用 父級字段的名稱。這樣在前台頁面就不用指定獲取數據源的url了

  public class DropdownListController : Controller
    {
        private List<Area> areas;

        private List<Language> languages;

        public DropdownListController()
        {
            areas = new List<Area>
            {
                new Area { Id = 1, Name = "中國", ParentId = null },
                new Area { Id = 2, Name = "美國", ParentId = null },
                new Area { Id = 3, Name = "江蘇省", ParentId = 1 },
                new Area { Id = 4, Name = "浙江省", ParentId = 1 },
                new Area { Id = 5, Name = "紐約州", ParentId = 2 },
                new Area { Id = 6, Name = "南京市", ParentId = 3 },
                new Area { Id = 7, Name = "杭州市", ParentId = 4 },
                new Area { Id = 8, Name = "紐約市", ParentId = 5 },
                new Area { Id = 9, Name = "曼哈頓區", ParentId = 8 },
                new Area { Id = 10, Name = "老廟區", ParentId = 6 },
                new Area { Id = 11, Name = "西湖區", ParentId = 7 }
            };

            languages = new List<Language>
            {
                new Language{ Id=1,CountryId=1, Name="簡體中文" },
                new Language{ Id=2,CountryId=2, Name="美式英語"},
            };
        }

        public IActionResult GetCountryId()
        {
            return Json(areas.FindAll(x => x.ParentId == null).Select(x => new { value = x.Id, text = x.Name }));
        }

        public IActionResult GetLanguageId(int countryId)
        {
            return Json(languages.FindAll(x => x.CountryId == countryId).Select(x => new { value = x.Id, text = x.Name }));
        }

        public IActionResult GetPronviceId(int countryId)
        {
            return Json(areas.FindAll(x => x.ParentId == countryId).Select(x => new { value = x.Id, text = x.Name }));
        }

        public IActionResult GetCityId(int pronviceId)
        {
            return Json(areas.FindAll(x => x.ParentId == pronviceId).Select(x => new { value = x.Id, text = x.Name }));
        }

        public IActionResult GetDistrictId(int cityId)
        {
            return Json(areas.FindAll(x => x.ParentId == cityId).Select(x => new { value = x.Id, text = x.Name }));
        }
    }

前台Html

引用了 bootstrap, jquery

@model UserModel

 <a asp-action="Edit" class="btn btn-success m-b-15">去編輯頁</a>
<div class="form-inline row">
    <div class="form-group ">
        <label>國家</label>
        <select asp-for="CountryId" class="form-control" asp-items="ViewBag.CountryList"
                data-select-childids="LanguageId,PronviceId">
            <option value="">請選擇</option>
        </select>
    </div>
    <div class="form-group ">
        <label>語言</label>
        <select asp-for="LanguageId" class="form-control">
            <option value="">請選擇</option>
        </select>
    </div>
    <div class="form-group">
        <label>省</label>
        <select asp-for="PronviceId" class="form-control" data-select-childids="CityId">
         <option value="">請選擇</option>
        </select>
    </div>
    <div class="form-group">
        <label>市</label>
        <select asp-for="CityId" class="form-control"   data-select-childids="DistrictId">
            <option value="">請選擇</option>
        </select>
    </div>
    <div class="form-group">
        <label>區</label>
        <select asp-for="DistrictId" class="form-control">
            <option value="">請選擇</option>
        </select>
    </div>
</div>

下拉聯動的js,基於 jquery

$(function () {
    //下拉聯動初始化
    $('select[data-select-childids]').each(function () {
        getChildSelect($(this).attr("id"), true);
    });

    //下拉聯動  data-select-childids 填寫聯動的Id,data-select-url 數據請求路徑,data-select-paramids 追加的參數,data-select-value 當前值
    $('select[data-select-childids]').change(function (e) {
        getChildSelect($(this).attr("id"));
    });

    //清空下拉聯動子選擇項
    function getChildSelect(selectid, isInit) {
        var select = $('#' + selectid);

        var selectchildIds = select.data('select-childids');
        if (!selectchildIds) return;
        var childIds = selectchildIds.split(',')

        for (var i = 0; i < childIds.length; i++) {
            if (!childIds[i]) continue;

            var child = $('#' + childIds[i]);
            var childValue = child.val();
            if (!childValue)
                childValue = child.data("select-value");

            child.empty();

            //默認值設定
            var hasdefault = child.data("select-hasdefault");
            if (hasdefault != "false") {
                child.append('<option value="">請選擇</option>');
            }

            //父級下拉有值時，ajax獲取數據
            if (select.val()) {var url = child.data('select-url') ? child.data('select-url') : '/DropdownList/Get' + child.attr("id");//url默認值
                var verb = child.data('verb') ? child.data('verb') : 'GET';//請求的方法

                var paramObj = {};//追加參數
                getParentSelectParam(selectid, paramObj)

                //追加控制參數
                var paramids = child.data('select-paramids');
                if (paramids) {
                    var paramidsArr = paramids.split(',')
                    for (var k = 0; k < paramidsArr.length; k++) {
                        paramObj[paramidsArr[k]] = $('#' + paramidsArr[k]).val();
                    }
                }

                $.ajax({
                    type: verb, url: url, data: paramObj, async: false,
                    contentype: "application/x-www-form-urlencoded; charset=UTF-8",
                    success: function (data) {
                        if (data) {
                            for (var j = 0; j < data.length; j++) {
                                var selected = data[j].value == childValue ? 'selected = "selected"' : '';
                                child.append('<option value="' + data[j].value + '" ' + selected + '>' + data[j].text + '</option>');
                            }
                        }
                    }
                });
            }

            //子級下拉如果還有下級,非初始化的時候 遞歸
            if (!isInit && child.data('select-childids'))
                getChildSelect(child.attr("id"));

        }
    }

    //遞歸獲取父級選中的值 param追加的url參數
    function getParentSelectParam(selectid, param) {
        var select = $("#" + selectid);
        param[selectid] = $(select).val();

        $('select[data-select-childids]').each(function () {
            var id = $(this).attr("id");
            if (selectid != id) {
                var childids = $(this).data('select-childids');
                if (childids) {
                    childidsArr = childids.split(',');
                    for (var i = 0; i < childidsArr.length; i++) {
                        if (childidsArr[i] == selectid) {
                            getParentSelectParam(id, param);//繼續向父級查找
                        }
                    }
                }
            }
        });
    }
});

后台 action

 public class HomeController : Controller
    {
        private List<Area> areas;

        public HomeController()
        {
            areas = new List<Area>
            {
                new Area { Id = 1, Name = "中國", ParentId = null },
                new Area { Id = 2, Name = "美國", ParentId = null },
                new Area { Id = 3, Name = "江蘇省", ParentId = 1 },
                new Area { Id = 4, Name = "浙江省", ParentId = 1 },
                new Area { Id = 5, Name = "紐約州", ParentId = 2 },
                new Area { Id = 6, Name = "南京市", ParentId = 3 },
                new Area { Id = 7, Name = "杭州市", ParentId = 4 },
                new Area { Id = 8, Name = "紐約市", ParentId = 5 },
                new Area { Id = 9, Name = "曼哈頓區", ParentId = 8 },
                new Area { Id = 10, Name = "老廟區", ParentId = 6 },
                new Area { Id = 11, Name = "西湖區", ParentId = 7 }
            };
        }

        public IActionResult Index()
        {
            ViewBag.CountryList = areas.FindAll(x => x.ParentId == null).Select(x =>
                                                                         new SelectListItem
                                                                         {
                                                                             Value = x.Id.ToString(),
                                                                             Text = x.Name
                                                                         });

            return View(new UserModel());
        }

        public IActionResult Edit()
        {
            ViewBag.CountryList = areas.FindAll(x => x.ParentId == null).Select(x =>
                                                                         new SelectListItem
                                                                         {
                                                                             Value = x.Id.ToString(),
                                                                             Text = x.Name
                                                                         });

            return View(new UserModel() { CountryId = 2, PronviceId = 5, CityId=8,DistrictId = 9, LanguageId = 2 });
        }
    }

運行效果

 

用法說明

<a asp-action="Index" class="btn btn-success m-b-15">返回</a>
<br /><br />
<div class="form-inline row">
    <div class="form-group ">
        <label>國家</label>
        <select asp-for="CountryId" class="form-control selectList" asp-items="ViewBag.CountryList"
                data-select-childids="LanguageId,PronviceId">
            <option value="">請選擇</option>
        </select>
    </div>
    <div class="form-group ">
        <label>語言</label>
        <select asp-for="LanguageId" class="form-control"
                data-select-value="@Model.LanguageId"  
                data-select-url="/DropDownList/GetLanguageId?id=1" 
                data-select-paramids="CountryId"  
                data-select-hasdefault="false" 
                data-verb="Get" 請求的方式
                >
            <option value="">請選擇</option>
        </select>
    </div>
    <div class="form-group">
        <label>省</label>
        <select asp-for="PronviceId" class="form-control"
                data-select-childids="CityId"
                data-select-value="@Model.PronviceId"
                data-select-url="/DropDownList/GetPronviceId?id=1"
                data-select-paramids="CountryId"
                >
            <option value="">請選擇</option>
        </select>
    </div>
    <div class="form-group">
        <label>市</label>
        <select asp-for="CityId" class="form-control"
                data-select-childids="DistrictId"
                data-select-value="@Model.CityId"
                data-select-url="/DropDownList/GetCityId"
                data-select-paramids="PronviceId"
                >
            <option value="">請選擇</option>
        </select>
    </div>
    <div class="form-group">
        <label>區</label>
        <select asp-for="DistrictId" class="form-control"
                data-select-value="@Model.DistrictId"
                data-select-url="/DropDownList/GetDistrictId"
                >
            <option value="">請選擇</option>
        </select>
    </div>
</div>

 

   data-select-childids ：設置聯動的select下拉的Id逗號分隔。例如在國家的下拉中 data-select-childids="LanguageId,PronviceId"表示，國家的下拉影響 語言和 省

   data-select-value:   數據加載時的初始值 用在編輯表單時,存儲當前下拉

   data-select-url: 請求的url

   data-select-paramids: 參數值的Id