Asp.Net Mvc: Model Binding to Simple Types, Complex Types, Collections, Dictionaries, Etc

环境：

Windows 2008, VS 2008 SP1, Asp.Net Mvc 1.0

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本文主要实验如何应用Asp.Net Mvc内建功能（DefaultModelBinder）实现简单类型、复杂类型、集合类型，以及字典类型的自动绑定。

1. 简单类型

这里，我们将下面这个Book类称为简单类型：

public class Book
    {
         public int BookId { get ; set ; }
         public string BookName { get ; set ; }
         public string Author { get ; set ; }
         public DateTime PublishedDate { get ; set ; }
    }

假设现在需要实现添加Book的功能，那么在BookController中，会定义如下的Action：

[AcceptVerbs(HttpVerbs.Post)]
         public ActionResult Create(Book book) {
             // TO DO
             // Insert book into Database
             return RedirectToAction( " Index " );
        }

现在的问题便是，在View中如何命名TextBox来达到自动绑定，如下：

< div >
         <% using (Html.BeginForm( " Create " , " Book " )) { %>
         < div >
            Book Name: <%= Html.TextBox( " BookName " ) %>
         </ div >
         < div >
            Author: <%= Html.TextBox( " Author " ) %>
         </ div >
         < div >
            Published Date: <%= Html.TextBox( " PublishedDate " ) %>
         </ div >
         < div >
             < input type = " submit " id = " submit " name = " submit " value = " submit " />
         </ div >
         <% } %>
     </ div >

注意TextBox的name必须是对应绑定类型的PropertyName（不区分大小写）。这样，页面表单submit后，我们便可以在BookController的“Create” Action中得到自动绑定的book对象。这里，Asp.Net Mvc还支持在TextBox的name中加上变量名称前缀的情形：

< div >
         <% using (Html.BeginForm( " Create " , " Book " )) { %>
         < div >
            Book Name: <%= Html.TextBox( " book.BookName " ) %>
         </ div >
         < div >
            Author: <%= Html.TextBox( " book.Author " ) %>
         </ div >
         < div >
            Published Date: <%= Html.TextBox( " book.PublishedDate " ) %>
         </ div >
         < div >
             < input type = " submit " id = " submit " name = " submit " value = " submit " />
         </ div >
         <% } %>
     </ div >

需要注意的是：
1）前缀"book"必须与Action中接收的Book参数名一致
2）如果加了前缀，那么所有的都要加

2. 复杂类型

现在对Book类作些许改动，并引入Author类：

public class Book
    {
         public int BookId { get ; set ; }
         public string BookName { get ; set ; }
         public Author Author { get ; set ; }
         public DateTime PublishedDate { get ; set ; }
    }

     public class Author {
         public int AuthorId { get ; set ; }
         public string AuthorName { get ; set ; }
         public string Nation { get ; set ; }
    }

这里，将改动后的Book类称为复杂类。这时，Book类多了一个对Author类的引用。现在，保持BookController中的"Create" Action不变，来看View中的TextBox改如何命名以实现Book类型的自动绑定：

< div >
         <% using (Html.BeginForm( " Create " , " Book " )) { %>
         < div >
            Book Name: <%= Html.TextBox( " BookName " ) %>
         </ div >
         < div >
            Published Date: <%= Html.TextBox( " PublishedDate " ) %>
         </ div >
         < div >
            Author ' s Name: <%=Html.TextBox("Author.AuthorName")%>
         </ div >
         < div >
            Author ' s Nation: <%=Html.TextBox("Author.Nation")%>
         </ div >
         < div >
             < input type = " submit " id = " submit " name = " submit " value = " submit " />
         </ div >
         <% } %>
     </ div >

OK，测试通过，想必你也知道命名规则了，要绑定Book类型中的Author类型，必须加上"Author."的前缀。
如果你喜欢，你还可以在所有TextBox名称前面再加"book."的前缀。

3. 集合类型

为避免问题复杂化，我们用回原来的简单Book类型：

现在，把BookController的"Create" Action改为接收IList<Book>的参数：

[AcceptVerbs(HttpVerbs.Post)]
         public ActionResult Create(IList < Book > books) {
             // TO DO
             // Insert book into Database
             return RedirectToAction( " Index " );
        }

然后，在View中运用以下命名规则，以自动绑定IList<book>类型，

< div >
         <% using (Html.BeginForm( " Create " , " Book " )) { %>
         < div >
            Book Name: <%= Html.TextBox( " books[0].BookName " ) %>
         </ div >
         < div >
            Published Date: <%= Html.TextBox( " books[0].PublishedDate " ) %>
         </ div >
         < div >
            Author ' s Name: <%=Html.TextBox("books[0].Author")%>
         </ div >
         < div >
            Book Name: <%= Html.TextBox( " books[1].BookName " ) %>
         </ div >
         < div >
            Published Date: <%= Html.TextBox( " books[1].PublishedDate " ) %>
         </ div >
         < div >
            Author ' s Name: <%=Html.TextBox("books[1].Author")%>
         </ div >
         < div >
             < input type = " submit " id = " submit " name = " submit " value = " submit " />
         </ div >
         <% } %>
     </ div >

可以看到如下规则：Action的变量名"books"加上中括号和索引作为前缀，索引必须从0开始，并且必须连续。
通过此命名规则，可以绑定任意集合类型：IList<Book>, ICollection<Book>, IEnumerable<Book>, List<Book>, Book[]等。

4. 字典类型

仍以简单Book类型为例，现在将"Create" Action改为接收IDictionary<Book>类型，

[AcceptVerbs(HttpVerbs.Post)]
         public ActionResult Create(IDictionary < string , Book > books) {
             // TO DO
             // Insert book into Database
             return RedirectToAction( " Index " );
        }

相应的，View中的命名如下：

< div >
         <% using (Html.BeginForm( " Create " , " Book " )) { %>
         < div >
            Book SN: <%= Html.TextBox( " books[0].Key " ) %>
         </ div >
         < div >
            Book Name: <%= Html.TextBox( " books[0].Value.BookName " ) %>
         </ div >
         < div >
            Published Date: <%= Html.TextBox( " books[0].Value.PublishedDate " ) %>
         </ div >
         < div >
            Author ' s Name: <%=Html.TextBox("books[0].Value.Author")%>
         </ div >
         < div >
            Book SN: <%= Html.TextBox( " books[1].Key " ) %>
         </ div >
         < div >
            Book Name: <%= Html.TextBox( " books[1].Value.BookName " ) %>
         </ div >
         < div >
            Published Date: <%= Html.TextBox( " books[1].Value.PublishedDate " ) %>
         </ div >
         < div >
            Author ' s Name: <%=Html.TextBox("books[1].Value.Author")%>
         </ div >
         < div >
             < input type = " submit " id = " submit " name = " submit " value = " submit " />
         </ div >
         <% } %>
     </ div >

可以看出，对于IDictioinary<Book>类型，在命名规则上，相比于集合类型，多了"Key"和"Value”的字眼。另，此规则也适用于Action参数类型为Dictionary<Book>的情形。

总结：

由此看来，只要我们遵循一定的命名规则，就可以轻松实现各种类型的自动绑定了。
当然，Asp.Net Mvc还支持自定义ModelBinder扩展，请看下回分解。:-)

参考文献：
Scott Hanselman：ASP.NET Wire Format for Model Binding to Arrays, Lists, Collections, Dictionaries

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Asp.Net Mvc: Model Binding to Simple Types, Complex Types, Collections, Dictionaries, Etc

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