在《为HtmlHelper添加一个RadioButtonList扩展方法》中我通过对HtmlHelper和HtmlHelper<Model>的扩展使我们可以采用”RadioButtonList”的方式对一组类型为“radio”的<input>元素进行操作。昨天对对此进行了一些改进，并将“CheckBoxList”的功能添加进来。[源代码从这里下载]

一、有何特别之处？

和我的很多文章一样，旨在提供一种大体的解决方案，本解决方案旨在解决如下一些问题：

通过独立的组件对绑定到ListControl（ Web Form的说法）的列表进行单独管理； 自动地调用上面这个组件获取列表信息进行相关Html的生成； 支持 MVC原生的Model Binding。

二、实例演示

我们还是以《为HtmlHelper添加一个RadioButtonList扩展方法》例子来演示RadioButtonList和CheckBoxList用法。下面是代表个人信息同时作为Model的Person类型，Gender、MaritalStatus 和Country分别代表性别、婚姻状况和国籍（这里支持多国籍）。

1: public class Person

2: {

3:public string Name { get; set; }

4:public string Gender { get; set; }

5:[Display(Name = "Marital Status")]

6:public string MaritalStatus { get; set; }

7:public string[] Country { get; set; }

8: }

上述三个属性分别代表CodeManager这个独立组件维护的三个列表，CodeManager和代表列表选项的CodeDescription定义如下：

1: public class CodeDescription

2: {

3:public string Code { get; set; }

4:public string Description { get; set; }

5:public string Category{get;set;}

6:

7:public CodeDescription(string code, string description, string category)

8:{

9: this.Code = code;

10: this.Description = description;

11: this.Category = category;

12:}

13: }

14: public static class CodeManager

15: {

16:private static CodeDescription[] codes = new CodeDescription[]

17:{

18: new CodeDescription("M","Male","Gender"),

19: new CodeDescription("F","Female","Gender"),

20: new CodeDescription("S","Single","MaritalStatus"),

21: new CodeDescription("M","Married","MaritalStatus"),

22: new CodeDescription("CN","China","Country"),

23: new CodeDescription("US","Unite States","Country"),

24: new CodeDescription("UK","Britain","Country"),

25: new CodeDescription("SG","Singapore","Country")

26:};

27:public static Collection<CodeDescription> GetCodes(string category)

28:{

29: Collection<CodeDescription> codeCollection = new Collection<CodeDescription>();

30: foreach(var code in codes.Where(code=>code.Category == category))

31: {

32: codeCollection.Add(code);

33: }

34: return codeCollection;

35:}

36: }

在默认的HomeController中，我们定义了如下两个Index方法，它们分别用于测试出栈数据（Model->UI)入栈数据（UI-〉Model）的绑定。

1: public class HomeController : Controller

2: {

3:public ActionResult Index()

4:{

5: return View(new Person { Name = "Foo", Gender = "M", MaritalStatus = "S", Country = new string[]{"CN","US"} });

6:}

7:[HttpPost]

8:public ActionResult Index(Person person)

9:{

10: return this.View(person);

11:}

12: }

下面是Index操作对应的View的定义，这是一个Model类型为Person的强类型View。对于Person的三个基于列表的属性，我们分别调用了自定义的扩展方法RadioButtonListFor和CheckBoxListFor进行了绑定。方法的最后两个参数分别代表通过CodeManager维护的列表的组别（Gender、MaritalStatus和Country），和同组RadioButton和CheckBox布局方向（水平或者纵向）。

1: @using System.Web.UI.WebControls

2: @model Person

3: @{

4:ViewBag.Title = "Index";

5: }

6: @using (Html.BeginForm())

7: {

8:<table id="container">

9: <tr>

10: <td class="label">@Html.LabelFor(m => m.Name):</td>

11: <td>@Html.EditorFor(m => m.Name)</td>

12: </tr>

13:<tr>

14: <td class="label">@Html.LabelFor(m => m.Gender):</td>

15: <td>@Html.RadioButtonListFor(m => m.Gender, "Gender")</td>

16: </tr>

17:<tr>

18: <td class="label">@Html.LabelFor(m => m.MaritalStatus):</td>

19: <td>@Html.RadioButtonListFor(m => m.MaritalStatus, "MaritalStatus")</td>

20: </tr>

21:<tr>

22: <td class="label">@Html.LabelFor(m => m.Country):</td>

23: <td>@Html.CheckBoxListFor(m => m.Country, "Country", RepeatDirection.Vertical)</td>

24: </tr>

25: <tr>

26: <td colspan="2"><input type="submit" value="Save" /></td>

27: </tr>

28:</table>

29: }

下面是最终呈现出来的效果：

三、两组扩展方法具体实现

现在我们简单地来看看RadioButtonList/RadioButtonListFor和CheckBoxList/CheckBoxListFor这两组扩展方法的实现。我们通过CodeManager得到列表集合，通过HtmlHelper结合 ModelMetadata得到当前数据，最终借助于ListControlUtil的GenerateHtml生成相关的Html。

1: public static class ListControlExtensions

2: {

3:public static MvcHtmlString RadioButtonList(this HtmlHelper htmlHelper, string name, string codeCategory, RepeatDirection repeatDirection = RepeatDirection.Horizontal)

4:{

5: var codes = CodeManager.GetCodes(codeCategory);

6: return ListControlUtil.GenerateHtml(name, codes, repeatDirection,"radio",null);

7:}

8:public static MvcHtmlString RadioButtonListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, string codeCategory, RepeatDirection repeatDirection = RepeatDirection.Horizontal)

9:{

10: var codes = CodeManager.GetCodes(codeCategory);

11: ModelMetadata metadata = ModelMetadata.FromLambdaExpression<TModel, TProperty>(expression, htmlHelper.ViewData);

12: string name = ExpressionHelper.GetExpressionText(expression);

13: string fullHtmlFieldName = htmlHelper.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(name);

14: return ListControlUtil.GenerateHtml(fullHtmlFieldName, codes, repeatDirection, "radio", metadata.Model);

15:}

16:

17:public static MvcHtmlString CheckBoxList(this HtmlHelper htmlHelper, string name, string codeCategory, RepeatDirection repeatDirection = RepeatDirection.Horizontal)

18:{

19: var codes = CodeManager.GetCodes(codeCategory);

20: return ListControlUtil.GenerateHtml(name, codes, repeatDirection, "checkbox", null);

21:}

22:public static MvcHtmlString CheckBoxListFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> expression, string codeCategory, RepeatDirection repeatDirection = RepeatDirection.Horizontal)

23:{

24: var codes = CodeManager.GetCodes(codeCategory);

25: ModelMetadata metadata = ModelMetadata.FromLambdaExpression<TModel, TProperty>(expression, htmlHelper.ViewData);

26: string name = ExpressionHelper.GetExpressionText(expression);

27: string fullHtmlFieldName = htmlHelper.ViewContext.ViewData.TemplateInfo.GetFullHtmlFieldName(name);

28: return ListControlUtil.GenerateHtml(fullHtmlFieldName, codes, repeatDirection, "checkbox", metadata.Model);

29:}

30: }

ListControlUtil中生成相关Html的逻辑定义如下：

1: public static class ListControlUtil

2: {

3:public static MvcHtmlString GenerateHtml(string name, Collection<CodeDescription> codes, RepeatDirection repeatDirection, string type, object stateValue)

4:{

5: TagBuilder table = new TagBuilder("table");

6: int i = 0;

7: bool isCheckBox = type == "checkbox";

8: if (repeatDirection == RepeatDirection.Horizontal)

9: {

10: TagBuilder tr = new TagBuilder("tr");

11: foreach (var code in codes)

12: {

13: i++;

14: string id = string.Format("{0}_{1}", name, i);

15: TagBuilder td = new TagBuilder("td");

16:

17: bool isChecked = false;

18: if (isCheckBox)

19: {

20: IEnumerable<string> currentValues = stateValue as IEnumerable<string>;

21: isChecked = (null != currentValues && currentValues.Contains(code.Code));

22: }

23: else

24: {

25: string currentValue = stateValue as string;

26: isChecked = (null != currentValue && code.Code == currentValue);

27: }

28:

29: td.InnerHtml = GenerateRadioHtml(name, id, code.Description, code.Code, isChecked,type);

30: tr.InnerHtml += td.ToString();

31: }

32: table.InnerHtml = tr.ToString();

33: }

34: else

35: {

36: foreach (var code in codes)

37: {

38: TagBuilder tr = new TagBuilder("tr");

39: i++;

40: string id = string.Format("{0}_{1}", name, i);

41: TagBuilder td = new TagBuilder("td");

42:

43: bool isChecked = false;

44: if (isCheckBox)

45: {

46: IEnumerable<string> currentValues = stateValue as IEnumerable<string>;

47: isChecked = (null != currentValues && currentValues.Contains(code.Code));

48: }

49: else

50: {

51: string currentValue = stateValue as string;

52: isChecked = (null != currentValue && code.Code == currentValue);

53: }

54:

55: td.InnerHtml = GenerateRadioHtml(name, id, code.Description, code.Code, isChecked, type);

56: tr.InnerHtml = td.ToString();

57: table.InnerHtml += tr.ToString();

58: }

59: }

60: return new MvcHtmlString(table.ToString());

61:}

62:

63:private static string GenerateRadioHtml(string name, string id, string labelText, string value, bool isChecked, string type)

64:{

65: StringBuilder sb = new StringBuilder();

66:

67: TagBuilder label = new TagBuilder("label");

68: label.MergeAttribute("for", id);

69: label.SetInnerText(labelText);

70:

71: TagBuilder input = new TagBuilder("input");

72: input.GenerateId(id);

73: input.MergeAttribute("name", name);

74: input.MergeAttribute("type", type);

75: input.MergeAttribute("value", value);

76: if (isChecked)

77: {

78: input.MergeAttribute("checked", "checked");

79: }

80: sb.AppendLine(input.ToString());

81: sb.AppendLine(label.ToString());

82: return sb.ToString();

83:}

84: }

通过对HtmlHelper扩展简化“列表控件”的绑定

为HtmlHelper添加一个RadioButtonList扩展方法

在 MVC中使用“RadioButtonList”和“CheckBoxList”