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

<?xml version="1.0" encoding="utf-8"?>
<mx:Application
    xmlns:mx="http://www.adobe.com/2006/mxml"
    width="500" height="470"
>

    <mx:Script>
        <![CDATA[
            [Bindable]
            private var myBooks:XML =
                <books>
                    <book ISBN="1590595181">
                        <title>Foundation ActionScript Animation: Making Things Move</title>
                        <author>Keith Peters</author>
                        <amazonUrl>http://tinyurl.com/npuxt</amazonUrl>
                        <price>1</price>
                    </book>
                    <book ISBN="1582346194">
                        <title>Send in the Idiots: Stories from the Other Side of Autism</title>
                        <author>Kamran Nazeer</author>
                        <amazonUrl>http://tinyurl.com/lo5ts</amazonUrl>
                        <price>2</price>
                    </book>
                </books>

            private function onClick():void
            {
                myBooks.book.(@ISBN=="1590595181")[0].price = 10
            }

            private function totalPrice(books:XML, price:String):int
            {
                var total:int = 0;
                for each(var item:XML in books.book)
                {
                    total += Number(item.price);
                }
                return total
            }
        ]]>
    </mx:Script>

    <mx:Panel
        title="Assigning XML data"
        paddingBottom="10" paddingLeft="10" paddingRight="10" paddingTop="10"
    >
        <mx:Button label="Button" click="onClick()"/>
        <mx:Label text="{totalPrice(myBooks,myBooks.book.price)}"/>
        <mx:Label text="{myBooks.book[0].price}"/>

    </mx:Panel>
</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>