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（ASP.NET 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ASP.NET MVC原生的Model Binding。
二、实例演示
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）。
public class Person
{
public string Name { get; set; }
public string Gender { get; set; }
[Display(Name = "Marital Status")]
public string MaritalStatus { get; set; }
public string[] Country { get; set; }
}
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：
public class CodeDescription
{
public string Code { get; set; }
public string Description { get; set; }
public string Category{get;set;}
public CodeDescription(string code, string description, string category)
{
this.Code = code;
this.Description = description;
this.Category = category;
}
}
public static class CodeManager
{
private static CodeDescription[] codes = new CodeDescription[]
{
new CodeDescription("M","Male","Gender"),
new CodeDescription("F","Female","Gender"),
new CodeDescription("S","Single","MaritalStatus"),
new CodeDescription("M","Married","MaritalStatus"),
new CodeDescription("CN","China","Country"),
new CodeDescription("US","Unite States","Country"),
new CodeDescription("UK","Britain","Country"),
new CodeDescription("SG","Singapore","Country")
};
public static Collection<CodeDescription> GetCodes(string category)
{
Collection<CodeDescription> codeCollection = new Collection<CodeDescription>();
foreach(var code in codes.Where(code=>code.Category == category))
{
codeCollection.Add(code);
}
return codeCollection;
}
}
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: {
} });
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: @{
5: }
6: @using (Html.BeginForm())
7: {
>
9: <tr>
>@Html.LabelFor(m => m.Name):</td>
11: <td>@Html.EditorFor(m => m.Name)</td>
12: </tr>
13: <tr>
>@Html.LabelFor(m => m.Gender):</td>
</td>
16: </tr>
17: <tr>
>@Html.LabelFor(m => m.MaritalStatus):</td>
</td>
20: </tr>
21: <tr>
>@Html.LabelFor(m => m.Country):</td>
</td>
24: </tr>
25: <tr>
/></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);
,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);
, 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);
, 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);
, 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: {
);
6: int i = 0;
;
8: if (repeatDirection == RepeatDirection.Horizontal)
9: {
);
11: foreach (var code in codes)
12: {
13: i++;
, name, i);
);
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: {
);
39: i++;
, name, i);
);
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:
);
, id);
69: label.SetInnerText(labelText);
70:
);
72: input.GenerateId(id);
, name);
, type);
, value);
76: if (isChecked)
77: {
);
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ASP.NET MVC中使用“RadioButtonList”和“CheckBoxList”