ASP.NET MVC中怎么实现下拉框绑定，很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。
下拉框硬编码【一】
我们在控制器中给出如下数据并利用ViewBag来进行传递
计算
安全
数据库
网络和加速
企业服务
ViewBag.hard_value = new List<SelectListItem>() {
new SelectListItem(){Value="0",Text="xpy0928"},
new SelectListItem(){Value="1",Text="cnblogs"}
};在数据中进行如下绑定
复制代码 代码如下:
@Html.DropDownList("hard-code-dropdownlist", new SelectList(ViewBag.hard_value, "Value", "Text"), new { @class = "btn btn-success dropdown-toggle form-control" })
下面我们来看看效果：
下拉框读取数据库【二】
这个要读取数据库，我们就给出一个类测试就ok，并给出默认选中值，测试类：
public class BlogCategory
{
public int CategoryId { get; set; }
public string CategoryName { get; set; }
}绑定ViewBag传值：
//从数据库中读取
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;视图稍加修改：
复制代码 代码如下:
@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 需要进行转换否则出现如下错误：
CS1973: “System.Web.Mvc.HtmlHelper<dynamic>”没有名为“DropDownList”的适用方法，但似乎有一个具有该名称的扩展方法。扩展方法不能进行动态调度。请考虑强制转换动态参数，或调用该扩展方法但不使用扩展方法语法。
下拉框绑定枚举【三】（一）
我们同样给出一个测试类：
public enum Language
{
Chinese,
English,
Japan,
Spanish,
Urdu
}获取枚举值并绑定：
ViewBag.from_enum = Enum.GetValues(typeof(Language)).Cast<Language>();视图给出：
复制代码 代码如下:
@Html.DropDownList("database-dropdownlist", new SelectList(ViewBag.from_enum), new { @class = "btn btn-success dropdown-toggle form-control" })
继续看看成果：
下拉框绑定枚举【三】（二）
利用扩展方法 @Html.EnumDropDownListFor 来实现。接下来依次给出两个类来进行演示：
public class StudentModel
{
[Display(Name = "语言")]
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
}在视图中进行绑定：
<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>我们看看结果
下拉框选择则另一个下拉框对应改变 【四】
此例最合适的例子莫过于省市选择的案例。我们一起来看看。
（1）所属省、市一级雇员类。
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 = "雇员名字")]
public string EmployeeName { get; set; }
[Required, Display(Name = "地址")]
public String Address { get; set; }
[Required, Display(Name = "所属省")]
public int Province { get; set; }
[Required, Display(Name = "所在城市")]
public int City { get; set; }
[Display(Name = "地区代码")]
public String ZipCode { get; set; }
[Required, Display(Name = "联系号码")]
public String Phone { get; set; }
}（2）初始化数据
List<Province> provinceList = new List<Province>() {
new Province(){provinceId=1,provinceName="湖南",Abbr="hunan_province"},
new Province(){provinceId=2,provinceName="广东",Abbr="guangdong_province"},
new Province(){provinceId=3,provinceName="吉林",Abbr="jilin_province"},
new Province(){provinceId=4,provinceName="黑龙江",Abbr="heilongjiang_province"}
};以及绑定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="岳阳市",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="哈尔滨市",provinceId=4}
};
cities = cities.Where(s => s.provinceId == provinceId).ToList();
return Json(cities, JsonRequestBehavior.AllowGet);
} （3）视图展示
@using (Html.BeginForm())
{
@Html.AntiForgeryToken()
<div class="form-horizontal">
<h5>注册雇员</h5>
<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"),
"选择所在省",
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"),
"选择所在市",
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）根据省下拉框选择到市下拉框脚本
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));
});
}
});
}我们来看看整个过程：
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