使用XML的Data Binding时一点注意

直接贴代码，下面的 绑定中 myBooks.book.price 这个参数在函数计算中没有用到，但是没有这个参数，price这个域的变化并不会触发函数的重新计算。

也许有人会跟我一样，想当然的觉得price变了也算整个myBooks变:)

xml 代码

 

1. <?xml version="1.0" encoding="utf-8"?>  
2. <mx:Application   
3.     xmlns:mx="http://www.adobe.com/2006/mxml"   
4.     width="500" height="470"  
5. >  
6.   
7.     <mx:Script>  
8.         <![CDATA[         
9.             [Bindable] 
10.             private var myBooks:XML =  
11.                 <books> 
12.                     <book ISBN="1590595181"> 
13.                         <title>Foundation ActionScript Animation: Making Things Move</title> 
14.                         <author>Keith Peters</author> 
15.                         <amazonUrl>http://tinyurl.com/npuxt</amazonUrl> 
16.                         <price>1</price> 
17.                     </book> 
18.                     <book ISBN="1582346194"> 
19.                         <title>Send in the Idiots: Stories from the Other Side of Autism</title> 
20.                         <author>Kamran Nazeer</author> 
21.                         <amazonUrl>http://tinyurl.com/lo5ts</amazonUrl> 
22.                         <price>2</price> 
23.                     </book> 
24.                 </books> 
25.              
26.             private function onClick():void 
27.             { 
28.                 myBooks.book.(@ISBN=="1590595181")[0].price = 10 
29.             } 
30.  
31.             private function totalPrice(books:XML, price:String):int 
32.             { 
33.                 var total:int = 0; 
34.                 for each(var item:XML in books.book) 
35.                 { 
36.                     total += Number(item.price); 
37.                 } 
38.                 return total 
39.             } 
40.         ]]>  
41.     </mx:Script>  
42.       
43.     <mx:Panel   
44.         title="Assigning XML data"  
45.         paddingBottom="10" paddingLeft="10" paddingRight="10" paddingTop="10"  
46.     >  
47.         <mx:Button label="Button" click="onClick()"/>  
48.         <mx:Label text="{totalPrice(myBooks,myBooks.book.price)}"/>  
49.         <mx:Label text="{myBooks.book[0].price}"/>  
50.   
51.     </mx:Panel>  
52. </mx:Application>  

<mx:application><mx:panel><mx:button label="Button" click="onClick()"><mx:label text="{totalPrice(myBooks,myBooks.book.price)}"><mx:label text="{myBooks.book[0].price}">     </mx:label>
</mx:label>

</mx:button></mx:panel></mx:application>