MVC视图中下拉框的使用

一、一般变量或对象的绑定

首先要在controller 中将选项设置成 selecList对象，并赋值给viewBag动态对象。

public ActionResult Index(string movieGenre,string searchString)
{
var GenreLst = new List<string>();
var GenreQry = from d in db.Movies
orderby d.Genre
select d.Genre;
GenreLst.AddRange(GenreQry.Distinct());
ViewBag.movieGenre = new SelectList(GenreLst);

var movies = from m in db.Movies
select m;
if (!string.IsNullOrWhiteSpace(searchString))
{
movies = movies.Where(s => s.Title.Contains(searchString));

}

if (!string.IsNullOrWhiteSpace(movieGenre))
{
movies = movies.Where(x => x.Genre == movieGenre);

}
return View(movies.ToList());
}

在View中有两种用法 

1、@Html.DropDownList("movieGenre", "All")   name=movieGenre,  自动读取viewBag.movieGenre 数据，也就是说会自动查找ViewBag对象的IEnumerable<SelectListItem >值。第二个参数下拉框是第一行显示的数据。

或者@Html.DropDownList("movieGenre"，null,new { @class="form-control"})

2、 @Html.DropDownList("movieGenre", ViewBag.movieGenre as SelectList,"全部", new { @class="form-control"})

@using (Html.BeginForm("Index", "Movie", FormMethod.Get, htmlAttributes: new { @class = "form-inline", role = "form" }))
{
<div class="form-group">
<label class="control-label" for="movieGenre">类别：</label>
</div>
<div class="form-group">
@Html.DropDownList("movieGenre", ViewBag.movieGenre as SelectList,"全部", new { @class="form-control"})
</div>
<div class="form-group">
<label for="searchString" class="control-label">&nbsp;&nbsp;片名:</label>
</div>
<div class="form-group">
@Html.TextBox("searchString", "", htmlAttributes: new { @class = "form-control", placeholder = "请输入片名" })
</div>
<input type="submit" value="查找" class="btn btn-primary" />
}

截图如下：

 二、 如果是bool类型变量的绑定到下拉框，也可以设置成下拉框的形式,选项分别为 全部，为真，为假。

控制器：

 public async Task<ActionResult> Index(string departmentID,string userRealName,bool? inCollege)

{

if (inCollege != null)
{
_users = _users.Where(u => u.InCollege == inCollege);
}

List<SelectListItem> listItem = new List<SelectListItem>();
listItem.Add(new SelectListItem { Value = true.ToString(), Text ="校内" });
listItem.Add(new SelectListItem { Value = false.ToString(), Text = "校外" });
ViewBag.InCollegeList = new SelectList(listItem, "Value", "Text");
ViewBag.CurrentinCollege = inCollege;

 }

视图：

<text>&nbsp;&nbsp;</text>

<label for="inCollege" class="control-label">校内或者校外：</label>
<div class="form-group">
@Html.DropDownList("inCollege", ViewBag.InCollegeList as SelectList, "全部", new { @class = "form-control" })
</div>

三、也可以直接在视图中指定bool值。

@Html.DorpdownListFor(x =>x.inCollege,new[] {new SelectListItem{ Value=bool.TureString,Text="校内"}，

new SelectListItem{Value=bool.FalseString,Text="校外"}

},"请选择")

四、也可以将枚举类型的绑定到下拉框中。

将枚举类型的值字符串作为传递参数，

控制器：

public ActionResult Index(string courseID, string resourceArrtibute, string searchTitle)
{
List<string> _resourceAttributeList = new List<string>();
_resourceAttributeList.AddRange(Enum.GetNames(typeof(ResourceArrtibute))); //通过Enum.GetNames(typeof(枚举类型))的值转换为字符串，并添加到List 泛型对象。
ViewBag.ResourceArrtibute = new SelectList(_resourceAttributeList, resourceArrtibute);  //返回所有枚举类型的值，并设定默认值。

ViewBag.SearchTitle = searchTitle;

List<Course> courses = new List<Course>();
var courseListQuery = from r in _resourceService.FindAll().Include(r =>r.Course)
select r.Course;
courses.AddRange(courseListQuery.Distinct().OrderBy(c =>c.CourseName));

ViewBag.CourseID = new SelectList(courses, "CourseID", "CourseName", courseID);
var resources = _resourceService.FindAll().Include(r => r.Course);
if(!string.IsNullOrEmpty(courseID))
{
resources = resources.Where(r => r.CourseID == courseID);

}

if (!string.IsNullOrEmpty(resourceArrtibute))
{
resources = resources.Where(r => r.ResourceArrtibute.ToString() == resourceArrtibute); //利用枚举类型的值的ToString()方法将枚举实例值转换为等效的字符串形式。

}

if (!string.IsNullOrEmpty(searchTitle))
{
resources = resources.Where(r => r.ResourceName.Contains(searchTitle));

}

return View(resources.ToList());
}

视图：

@using (Html.BeginForm("Index", "Resource", FormMethod.Get, new { @class = "form-inline", role = "form" }))
{
<label for="CourseID" class="control-label">课程名称：</label>
<div class="form-group">
@Html.DropDownList("CourseID",null,"全部课程", new { @class="form-control" })
</div>

<label for="ResourceArrtibute" class="control-label">资源类型：</label>
<div class="form-group">
@Html.DropDownList("ResourceArrtibute", null, "全部类型", htmlAttributes: new { @class = "form-control" })  //将字符串形式的selectlist对象绑定到下拉菜单上。
</div>

<label for="searchTextbox" class="control-label"> 通过资源标题查找：</label>
<div class="form-group">
@Html.TextBox("SearchTitle", ViewBag.SearchTitle as string, new { @class = "form-control" })
</div>

<input type="submit" value="查找" class="btn btn-primary" />

}

枚举类型的变量绑定详细可参见博客园另一篇文章

http://www.cnblogs.com/liuyuanhao/p/4510382.html