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 程式師世界 >> 編程語言 >> .NET網頁編程 >> ASP.NET >> ASP.NET基礎 >> 詳解ASP.NET MVC之下拉框綁定四種方式

詳解ASP.NET MVC之下拉框綁定四種方式

編輯:ASP.NET基礎

前言

上兩節我們講了文件上傳的問題,關於這個上傳的問題還未結束,我也在花時間做做分割大文件處理以及顯示進度的問題,到時完成的話再發表,為了不耽誤學習MVC其他內容的計劃,我們今天開始好好講講關於MVC中下拉框中綁定枚舉的幾種方式。

話題引入

一般在下拉框中綁定數據的話,分為幾種情況。

(1)下拉框中的數據是寫死的,我們直接給出死代碼即可。

(2)下拉框中的數據從數據庫中讀取出來,從而進行顯示。

(3)下拉框中直接用枚舉顯示。

(4)下拉框中一個選擇的值改變另外一個下拉框中的值。

關於下拉框中綁定大概就是以上四種方式,接下來我們一一來破解,我們樣式利用Bootstrap來表示,順便也溫習溫習Bootstrap。

下拉框硬編碼【一】

我們在控制器中給出如下數據並利用ViewBag來進行傳遞

   ViewBag.hard_value = new List<SelectListItem>() { 
    new SelectListItem(){Value="0",Text="xpy0928"},
    new SelectListItem(){Value="1",Text="cnblogs"}
   };

在數據中進行如下綁定

復制代碼 代碼如下:
 @Html.DropDownList("hard-code-dropdownlist", new SelectList(ViewBag.hard_value, "Value", "Text"), new { @class = "btn btn-success dropdown-toggle form-control" })

下面我們來看看效果:

下拉框讀取數據庫【二】

這個要讀取數據庫,我們就給出一個類測試就ok,並給出默認選中值,測試類:

public class BlogCategory
  {
   public int CategoryId { get; set; }
   public string CategoryName { get; set; }

  }

綁定ViewBag傳值:

//從數據庫中讀取
   var categoryList = new List<BlogCategory>() { 
    new BlogCategory(){CategoryId=1,CategoryName="C#"},
    new BlogCategory(){CategoryId=2,CategoryName="Java"},
    new BlogCategory(){CategoryId=3,CategoryName="JavaScript"},
    new BlogCategory(){CategoryId=4,CategoryName="C"}
   };
   var selectItemList = new List<SelectListItem>() { 
    new SelectListItem(){Value="0",Text="全部",Selected=true}
   };
   var selectList = new SelectList(categoryList, "CategoryId", "CategoryName");
   selectItemList.AddRange(selectList);
   ViewBag.database = selectItemList;

視圖稍加修改:

復制代碼 代碼如下:
@Html.DropDownList("database-dropdownlist", ViewBag.database as IEnumerable<SelectListItem>, new { @class = "btn btn-success dropdown-toggle form-control" })

看看效果:

中 ViewBag.database 需要進行轉換否則出現如下錯誤:

 CS1973: “System.Web.Mvc.HtmlHelper<dynamic>”沒有名為“DropDownList”的適用方法,但似乎有一個具有該名稱的擴展方法。擴展方法不能進行動態調度。請考慮強制轉換動態參數,或調用該擴展方法但不使用擴展方法語法。

下拉框綁定枚舉【三】(一)

 我們同樣給出一個測試類:

public enum Language
  {
   Chinese,
   English,
   Japan,
   Spanish,
   Urdu
  }

獲取枚舉值並綁定:

 ViewBag.from_enum = Enum.GetValues(typeof(Language)).Cast<Language>();

視圖給出:

復制代碼 代碼如下:
@Html.DropDownList("database-dropdownlist", new SelectList(ViewBag.from_enum), new { @class = "btn btn-success dropdown-toggle form-control" })

繼續看看成果:

下拉框綁定枚舉【三】(二)

 利用擴展方法  @Html.EnumDropDownListFor 來實現。接下來依次給出兩個類來進行演示:

 public class StudentModel
 {
  [Display(Name = "語言")]
  public ProgrammingLanguages Language { get; set; }
 }
public enum ProgrammingLanguages
 {
  [Display(Name = "ASP.NET")]
  ASPNet,
  [Display(Name = "C# .NET")]
  CSharp,
  [Display(Name = "Java")]
  Java,
  [Display(Name = "Objective C")]
  ObjectiveC,
  [Display(Name = "Visual Basic .NET")]
  VBNet,
  [Display(Name = "Visual DataFlex")]
  VisualDataFlex,
  [Display(Name = "Visual Fortran")]
  VisualFortran,
  [Display(Name = "Visual FoxPro")]
  VisualFoxPro,
  [Display(Name = "Visual J++")]
  VisualJPlus
 }

在視圖中進行綁定:

 <div class="form-group">
  @Html.LabelFor(model => model.Language, htmlAttributes: new { @class = "control-label col-md-2" })
  <div class="col-md-10">
   @Html.EnumDropDownListFor(model => model.Language, htmlAttributes: new { @class = "form-control" })
   @Html.ValidationMessageFor(model => model.Language, "", new { @class = "text-danger" })
  </div>
 </div>

我們看看結果

下拉框選擇則另一個下拉框對應改變 【四】

此例最合適的例子莫過於省市選擇的案例。我們一起來看看。

(1)所屬省、市一級雇員類。

public class Province
 {
  public int provinceId { get; set; }
  public string provinceName { get; set; }
  public string Abbr { get; set; }
 }
public class City
 {
  public int CityId { get; set; }
  public string CityName { get; set; }
  public int provinceId { get; set; }
 }
public class Employees
 {

  [Key]
  public int EmployeeId { get; set; }

  [Required, Display(Name = "雇員名字")]
  public string EmployeeName { get; set; }

  [Required, Display(Name = "地址")]
  public String Address { get; set; }

  [Required, Display(Name = "所屬省")]
  public int Province { get; set; }

  [Required, Display(Name = "所在城市")]
  public int City { get; set; }

  [Display(Name = "地區代碼")]
  public String ZipCode { get; set; }

  [Required, Display(Name = "聯系號碼")]
  public String Phone { get; set; }
 }

(2)初始化數據

List<Province> provinceList = new List<Province>() { 
    new Province(){provinceId=1,provinceName="湖南",Abbr="hunan_province"},
    new Province(){provinceId=2,provinceName="廣東",Abbr="guangdong_province"},
    new Province(){provinceId=3,provinceName="吉林",Abbr="jilin_province"},
    new Province(){provinceId=4,provinceName="黑龍江",Abbr="heilongjiang_province"}
   };

以及綁定ViewBag到下拉框和控制器上的方法:

[HttpGet]
  public ActionResult Create()
  {

   ViewBag.ProvinceList = provinceList;
   var model = new Employees();
   return View(model);
  }

  [HttpPost]
  public ActionResult Create(Employees model)
  {
   if (ModelState.IsValid)
   {

   }
   ViewBag.ProvinceList = provinceList;
   return View(model);
  }

  public ActionResult FillCity(int provinceId)
  {
   var cities = new List<City>() {
    new City(){CityId=10,CityName="岳陽市",provinceId=1},
    new City(){CityId=10,CityName="深圳市",provinceId=2},
    new City(){CityId=10,CityName="吉林市",provinceId=3},
    new City(){CityId=10,CityName="哈爾濱市",provinceId=4}
   };
   cities = cities.Where(s => s.provinceId == provinceId).ToList();
   return Json(cities, JsonRequestBehavior.AllowGet);
  }

 (3)視圖展示
 

@using (Html.BeginForm())
 {
  @Html.AntiForgeryToken()

  <div class="form-horizontal">
   <h4>注冊雇員</h4>
   <div class="form-group">
    @Html.LabelFor(m => m.EmployeeName, new { @class = "control-label col-md-2" })
    <div class="col-md-10">
     @Html.TextBoxFor(m => m.EmployeeName, new { @class = "form-control" })
     @Html.ValidationMessageFor(m => m.EmployeeName, "", new { @class = "text-danger" })
    </div>
   </div>
   <div class="form-group">
    @Html.LabelFor(m => m.Address, new { @class = "control-label col-md-2" })
    <div class="col-md-10">
     @Html.TextBoxFor(m => m.Address, new { @class = "form-control" })
     @Html.ValidationMessageFor(m => m.Address, "", new { @class = "text-danger" })
    </div>
   </div>
   <div class="form-group">
    @Html.LabelFor(m => m.Province, new { @class = "control-label col-md-2" })
    <div class="col-md-10">
     @Html.DropDownListFor(m => m.Province,
new SelectList(ViewBag.ProvinceList, "provinceId", "provinceName"),
     "選擇所在省",
     new { @class = "form-control", @onchange = "FillCity()" })
     @Html.ValidationMessageFor(m => m.Province, "", new { @class = "text-danger" })
    </div>
   </div>
   <div class="form-group">
    @Html.LabelFor(m => m.City, new { @class = "control-label col-md-2" })
    <div class="col-md-10">
     @Html.DropDownListFor(m => m.City,
   new SelectList(Enumerable.Empty<SelectListItem>(), "CityId", "CityName"),
     "選擇所在市",
     new { @class = "form-control" })
     @Html.ValidationMessageFor(m => m.City, "", new { @class = "text-danger" })
    </div>
   </div>
   <div class="form-group">
    @Html.LabelFor(m => m.ZipCode, htmlAttributes: new { @class = "control-label col-md-2" })
    <div class="col-md-10">
     @Html.TextBoxFor(m => m.ZipCode, new { @class = "form-control" })
     @Html.ValidationMessageFor(m => m.ZipCode, "", new { @class = "text-danger" })
    </div>
   </div>
   <div class="form-group">
    @Html.LabelFor(m => m.Phone, new { @class = "control-label col-md-2" })
    <div class="col-md-10">
     @Html.TextBoxFor(m => m.Phone, new { @class = "form-control" })
     @Html.ValidationMessageFor(m => m.Phone, "", new { @class = "text-danger" })
    </div>
   </div>
   <div class="form-group">
    <div class="col-md-offset-2 col-md-10">
     <input type="submit" value="Create" class="btn btn-success" />
     <a href="/Home/Employees" class="btn btn-warning">Cancel</a>
    </div>
   </div>
  </div>
 }

(4)根據省下拉框選擇到市下拉框腳本

function FillCity() {
   var provinceId = $('#Province').val();
   $.ajax({
    url: '/Home/FillCity',
    type: "GET",
    dataType: "JSON",
    data: { provinceId: provinceId },
    success: function (cities) {
     $("#City").html("");
     $.each(cities, function (i, city) {
      $("#City").append(
       $('<option></option>').val(city.CityId).html(city.CityName));
     });
    }
   });
  }

我們來看看整個過程:

結語

對於下拉框綁定基本上已全部囊括進去,以上就是本文的全部內容,希望對大家的學習有所幫助,也希望大家多多支持腳本之家。

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