Question

我必须使用@ Html.CheckBoxListFor＆lt;＆gt;或@ Html.DropdownListFor＆lt;＆gt;。我对如何在View whild中使用这些帮助器类感到困惑，我使用List进行模型绑定。

将List绑定到CheckBoxList和DropdownList的正确和最简单的方法是什么。

在模型中：

public class SampleViewModel
    {
        public IEnumerable<Responsible> AvailableResponsibles { get; set; }
        public IEnumerable<Responsible> SelectedResponsibles { get; set; }
        public PostedResponsibles PostedResponsibles { get; set; }
        Responsible objResponsible = new Responsible();
        public SampleViewModel GetResponsiblesInitialModel()
        {
            //setup properties
            var model = new SampleViewModel();
            var selectedResponsibles = new List<Responsible>();

            //setup a view model
            model.AvailableResponsibles = objResponsible.GetAll().ToList();
            model.SelectedResponsibles = selectedResponsibles;
            return model;
        }
    }
public class Responsible
    {
        //Integer value of a checkbox
        public int Id { get; set; }

        //String name of a checkbox
        public string Name { get; set; }

        //Boolean value to select a checkbox
        //on the list
        public bool IsSelected { get; set; }

        //Object of html tags to be applied
        //to checkbox, e.g.:'new{tagName = "tagValue"}'
        public object Tags { get; set; }

        public IEnumerable<Responsible> GetAll()
        {
            return new List<Responsible> {
                              new Responsible {Name = "Apple", Id = 1 },
                              new Responsible {Name = "Banana", Id = 2},
                              new Responsible {Name = "Cherry", Id = 3},
                              new Responsible {Name = "Pineapple", Id = 4},
                              new Responsible {Name = "Grape", Id = 5},
                              new Responsible {Name = "Guava", Id = 6},
                              new Responsible {Name = "Mango", Id = 7}
                            };
        }

    }

    public class PostedResponsibles
    {
        //this array will be used to POST values from the form to the controller
        public string[] ResponsibleIds { get; set; }
    }

并且查看是：

<tr>
                <td>
                    @Html.LabelFor(model=>model.Responsible)
                </td>
                <td>
                  @Html.CheckBoxListFor(model => model.PostedResponsibles.ResponsibleIds,
                                  model => model.AvailableResponsibles,
                                  Responsible => Responsible.Id,
                                  Responsible => Responsible.Name,
                                  model => model.SelectedResponsibles)

                </td>
            </tr>

目前我正在使用Nuget Packege但它有点令人困惑且难以使用。请将其他任何其他内容用于实现此目的。

Answer 1

使用包管理器步骤安装包
```
Install-Package MvcCheckBoxList
```

添加 Fruit.cs

namespace CheckBoxListForApp.Models
{
  public class Fruit
  {
      public int Id { get;set;}
      public string Name { get;set; }  
      public bool IsSelected{get;set;}
      public object Tags { get;set;}
  }
}

添加 FruitViewModel.cs

using System.Collections.Generic;
namespace CheckBoxListForApp.Models
{
  public class FruitViewModel
  {
    public IEnumerable<Fruit> AvailableFruits { get; set; }
    public IEnumerable<Fruit> SelectedFruits { get; set; }
    public PostedFruits PostedFruits { get; set; }
  }
}

添加已发布的.Fruits.cs

namespace CheckBoxListForApp.Models
{
    /// <summary>
    /// for Helper class to make posting back selected values easier
    /// </summary>
    public class PostedFruits
    {
        //this array will be used to POST values from the form to the controller
        public string[] FruitIds { get; set; }
    }
}

添加 HomeController.cs

using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Web.Mvc;
using CheckBoxListForApp.Models;

namespace CheckBoxListForApp.Controllers
{
    public class HomeController : Controller
    {

        [HttpGet]
        public ActionResult Index()
        {
            return View(GetFruitsInitialModel());
        }


        [HttpPost]
        public ActionResult Index(PostedFruits postedFruits)
        {
            return View(GetFruitsModel(postedFruits));
        }

        private FruitViewModel GetFruitsModel(PostedFruits postedFruits)
        {

            var model = new FruitViewModel();
            var selectedFruits = new List<Fruit>();
            var postedFruitIds = new string[0];
            if (postedFruits == null) postedFruits = new PostedFruits();

            // if a view model array of posted fruits ids exists
            // and is not empty,save selected ids
            if (postedFruits.FruitIds != null && postedFruits.FruitIds.Any())
            {
                postedFruitIds = postedFruits.FruitIds;
            }

            // if there are any selected ids saved, create a list of fruits
            if (postedFruitIds.Any())
            {
              selectedFruits = FruitRepository.GetAll()
               .Where(x => postedFruitIds.Any(s => x.Id.ToString().Equals(s)))
               .ToList();
            }


            model.AvailableFruits = FruitRepository.GetAll().ToList();
            model.SelectedFruits = selectedFruits;
            model.PostedFruits = postedFruits;
            return model;
        }

        private FruitViewModel GetFruitsInitialModel()
        {

            var model = new FruitViewModel();
            var selectedFruits = new List<Fruit>();


            model.AvailableFruits = FruitRepository.GetAll().ToList();
            model.SelectedFruits = selectedFruits;
            return model;
        }
    }
}

添加 FruitRepository.cs

using System.Collections.Generic;
using System.Linq;

namespace CheckBoxListForApp.Models
{
    /// <summary>
    /// work as fruit repository
    /// </summary>
    public static class FruitRepository
    {
        /// <summary>
        /// for get fruit for specific id
        /// </summary>
        public static Fruit Get(int id)
        {
            return GetAll().FirstOrDefault(x => x.Id.Equals(id));
        }

        /// <summary>
        /// for get all fruits
        /// </summary>
        public static IEnumerable<Fruit> GetAll()
        {
            return new List<Fruit> {
                              new Fruit {Name = "Apple", Id = 1 },
                              new Fruit {Name = "Banana", Id = 2},
                              new Fruit {Name = "Cherry", Id = 3},
                              new Fruit {Name = "Pineapple", Id = 4},
                              new Fruit {Name = "Grape", Id = 5},
                              new Fruit {Name = "Guava", Id = 6},
                              new Fruit {Name = "Mango", Id = 7}
                            };
        }
    }
}

添加 Index.cshtml

@using MvcCheckBoxList.Model
@model CheckBoxListForApp.Models.FruitViewModel

@{
    ViewBag.Title = "Home Page";
}

<section class="checkBoxListFor">
    <p>
        <label>Please Select Fruits:</label>
        @using (Html.BeginForm("Index", "Home", FormMethod.Post))
        {
            @Html.CheckBoxListFor(model => model.PostedFruits.FruitIds,
                                  model => model.AvailableFruits,
                                  fruit => fruit.Id,
                                  fruit => fruit.Name,
                                  model => model.SelectedFruits,
                                  Position.Horizontal)
            <input class="green" type="submit" 
                      value="POST to Controller" />
        }
    </p>
</section>

Answer 2

这取决于您的UI要求。如果你需要一个下拉列表，那就使用它。

CheckBoxList不是开箱即用的助手，它是一个自定义助手。

您可以在此处Code Project

找到帮助程序（CheckBoxList）的更多详细信息

关于下拉请参阅MSDN。它可以通过多种方式重载。

以下是可用的ASP.NET MVC helpers

如何在MVC4 Razor中使用CheckBoxList和DropdownList

2 个答案: