本文转自：http://www.aspnetmvcninja.com/views/asp-net-mvc-select-list-example

Select lists are a great way to allow users to select multiple options from a long list of possible values. But how do you implement a select list in ASP.NET MVC? Luckily ASP.NET MVC does most of the heavy lifting for you. For this example I’m going to use a product that has multiple categories.

I’ll start by defining two model classes. The first class is called Category and I’ll use a list of them to store the possible values that will be displayed in the select list. For this example I’ll manually populate these in the controller but you could just as easily load them from a database. The other class is Product which has many category ID’s stored in the CategoryID property (a collection of int’s).

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
namespace MvcApplication2.Models
{
    public class Category
    {
        public int ID { get; set; }
 
        public string Name { get; set; }
    }
 
    public class Product
    {
        public ICollection<int> CategoryID { get; set; }
 
        public Product()
        {
            CategoryID = new List<int>();
        }
    }
}

Next we need a controller.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
namespace MvcApplication2.Controllers
{
    public class HomeController : Controller
    {
        private List<Category> GetOptions()
        {
            List<Category> categories = new List<Category>();
            categories.Add(new Category() { ID = 1, Name = "Bikes" });
            categories.Add(new Category() { ID = 2, Name = "Cars" });
            categories.Add(new Category() { ID = 3, Name = "Trucks" });
 
            return categories;
        }
 
        public ActionResult Index()
        {
            Product product = new Product();
            ViewBag.Categories = GetOptions();
            return View(product);
        }
 
        [HttpPost]
        public ActionResult Index(Product product)
        {
            ViewBag.Categories = GetOptions();
            return View(product);
        }
    }
}

I’ve created a private method called GetOptions() to populate a list with the categories. In real world applications you’ll have a service (business logic) class that provides these.

GET requests are handled by the first Index action. It passes the select list options to the view using the ViewBag. You could use ViewData just as easily. It also creates a new Product which becomes the model for the view. If you want to pre-select values then simply add them as follows:

1
2
product.CategoryID.Add(1);
product.CategoryID.Add(3);

The second Index action handles POST requests. The values for product are populated by the default binder that comes with ASP.NET MVC. This will add all of the values the user selected on the form so you don’t need to do anything.

Finally I have a view that displays the selected values as an unordered list with a select list below it allowing you to change the selected options.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
<%@ Page Language="C#" Inherits="System.Web.Mvc.ViewPage<MvcApplication2.Models.Product>" %>
 
<!DOCTYPE html>
 
<html>
<head runat="server">
    <title>ASP.NET MVC Select List Example</title>
    <link type="text/css" href="../../Content/Site.css" rel="Stylesheet" />
</head>
<body>
    <div>
 
<h1>Select Values</h1>
<ul>
<% foreach (int c in Model.CategoryID)
   { %>
   <li><%: c %></li>
<% } %>
</ul>
<%: Html.DisplayForModel() %>
 
<h1>Change Values</h1>
<% using (Html.BeginForm())
   { %>
   <%: Html.ListBoxFor(x => x.CategoryID, new MultiSelectList(ViewBag.Categories, "ID", "Name", Model.CategoryID)) %>
   <br />
   <input type="submit" value="Submit" />
<% } %>
    </div>
</body>
</html>

In the view I’m using the Html.ListBoxFor() helper to render the select list. The second value passed to this is a list of options which I’m building using the MultiSelectList class. The constructor I’m using accepts 4 parameters:

  1. A list of options. In our example it’s List<Category>.
  2. The name of the property that contains the value used in the select list. I’m using “ID” here because I want to use the ID property of Category.
  3. The name of the property the contains the text to use for each option. I’m using “Name” here because I want to use the Name property of Category.
  4. A list of currently select values.

You may be wondering why I pass a list of Category objects to the view instead of creating the MultiSelectList in the controller and then passing that to the view. Personally I find creating the MultiSelectList in the controller both makes the controller more complicated and mixes view logic with controller logic. I also find this approach works better in real world applications where you are probably getting the list of options from a service class. By doing it this way it’s possible to mock the service and test that the value returned by the service class is passed to the view correctly when writing unit tests.

Here’s what it looks like when you first display the select list…

… and after you’ve selected some values

- See more at: http://www.aspnetmvcninja.com/views/asp-net-mvc-select-list-example#sthash.bzAba6tW.dpuf

[转]ASP.NET MVC Select List Example的更多相关文章

  1. ASP.NET MVC Select无限级分类选择下拉框

    1:读取父级下的所有子类别 *ViewBag.ParentItemList:不能与ParentId相同 private void ParentDropDownList() { List<SAS. ...

  2. asp.net mvc select用法

    var statusSelectItems = new List<SelectListItem> { "}, "}, "}, "}, "} ...

  3. 在ASP.NET MVC中实现Select多选

    我们知道,在ASP.NET MVC中实现多选Select的话,使用Html.ListBoxFor或Html.ListBox方法就可以.在实际应用中,到底该如何设计View Model, 控制器如何接收 ...

  4. ASP.NET MVC with Entity Framework and CSS一书翻译系列文章之第二章：利用模型类创建视图、控制器和数据库

    在这一章中,我们将直接进入项目,并且为产品和分类添加一些基本的模型类.我们将在Entity Framework的代码优先模式下,利用这些模型类创建一个数据库.我们还将学习如何在代码中创建数据库上下文类 ...

  5. ASP.NET MVC开发：Web项目开发必备知识点

    最近加班加点完成一个Web项目,使用Asp.net MVC开发.很久以前接触的Asp.net开发还是Aspx形式,什么Razor引擎,什么MVC还是这次开发才明白,可以算是新手. 对新手而言,那进行A ...

  6. 【第三篇】ASP.NET MVC快速入门之安全策略（MVC5+EF6）

    目录 [第一篇]ASP.NET MVC快速入门之数据库操作(MVC5+EF6) [第二篇]ASP.NET MVC快速入门之数据注解(MVC5+EF6) [第三篇]ASP.NET MVC快速入门之安全策 ...

  7. ASP.NET MVC 使用 Petapoco 微型ORM框架+NpgSql驱动连接 PostgreSQL数据库

    前段时间在园子里看到了小蝶惊鸿 发布的有关绿色版的Linux.NET——“Jws.Mono”.由于我对.Net程序跑在Linux上非常感兴趣,自己也看了一些有关mono的资料,但是一直没有时间抽出时间 ...

  8. 使用Metrics.NET 构建 ASP.NET MVC 应用程序的性能指标

    通常我们需要监测ASP.NET MVC 或 Web API 的应用程序的性能时,通常采用的是自定义性能计数器,性能计数器会引发无休止的运维问题(损坏的计数器.权限问题等).这篇文章向你介绍一个新的替代 ...

  9. 你从未知道如此强大的ASP.NET MVC DefaultModelBinder

    看到很多ASP.NET MVC项目还在从request.querystring或者formContext里面获取数据,这实在是非常落后的做法.也有的项目建了大量的自定义的modelbinder,以为很 ...

随机推荐

  1. HIbernate学习笔记（二） hibernate对象的三种状态与核心开发接口

    1.在hibernate中持久化对象有三个状态,这个面试时可能会问到: (1)transient瞬时态:在数据库中没有与之匹配的数据,一般就是只new出了这个对象,并且在session缓存中也没有即此 ...

  2. 析构函数释放内存时出现_BLOCK_TYPE_IS_VALID错误

    错误信息截图: 原因: 1.内存泄漏:所以当程序退出时,系统会收回分配的内存,于是调析构函数,由于内存已被错误地释放,于是就会出现"Debug Assertion Failed"的 ...

  3. ExtJs4.1实现数据缓存

    Ext.onReady(function () {             Ext.define("ProvinceCity", {                 extend: ...

  4. HBase in 2013

    2013年马上就要过去了,总结下这一年HBase在这么一年中发生的主要变化.影响最大的事件就是HBase 0.96的发布,代码结构已经按照模块化release了,而且提供了许多大家迫切需求的特点.这些 ...

  5. Activity的生命周期，BACK键和HOME键生命周期

    Activity的生命周期模型在Google提供的官方文档上有比较详细的一个图示 public class HelloActivity extends Activity { public static ...

  6. 0 Explore TreeView

    尽可能接近WINDOWS 8的资源管理器效果(这里只模仿它的效果,处理文件功能不包括在内)   TREEVIEW可以增加空白并且空白处不能单击 重绘三角箭头 重绘选中时的边框和填充色 重绘失去焦点时选 ...

  7. ORACLE 毫秒与日期的相互转换

    毫秒转换为日期 SELECT TO_CHAR(1406538765000 / (1000 * 60 * 60 * 24) + TO_DATE('1970-01-01 08:00:00', 'YYYY- ...

  8. Android端如何获取手机当前的网络状态,比如wifi还是3G, 还是2G, 电信还是联通,还是移动

    不多说了,直接看代码, NB人会懂的! package com.example.vdisktest; import android.app.Activity; import android.conte ...

  9. iOS开发——适配篇&iOS9适配

    iOS9适配 1. Demo1_iOS9网络适配_ATS:改用更安全的HTTPS [摘要]iOS9把所有的http请求都改为https了:iOS9系统发送的网络请求将统一使用TLS 1.2 SSL.采 ...

  10. 代理模式及其在spring与struts2中的体现

    代理模式 代理模式有三个角色组成: 1．抽象主题角色:声明了真实主题和代理主题的共同接口. 2．代理主题角色:内部包含对真实主题的引用,并且提供和真实主题角色相同的接口. 3．真实主题角色:定义真实的 ...