Question

我有一个DropDownList的两个dataProvider。可以编译和运行以下代码。

<?xml version="1.0" encoding="utf-8"?>
<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009"
   xmlns:s="library://ns.adobe.com/flex/spark"
   xmlns:mx="library://ns.adobe.com/flex/mx"
   creationComplete="flipLast()"
   minWidth="955" minHeight="600">
<fx:Script>
<![CDATA[
     import mx.collections.ArrayCollection;
     public function flipLast():void {
          if( last ) {
               list.dataProvider = dp1;
               list.selectedItem = "Flex";
          } else {
               list.dataProvider = dp2;
               list.selectedItem = "Catalyst";        
          }
          last = !last;
     }

     public var last:Boolean = true;
     public var dp1:ArrayCollection = new ArrayCollection( [ "Flex", "Air" ] );
     public var dp2:ArrayCollection = new ArrayCollection( [ "Catalyst", "FlashBuilder" ] );
]]>
</fx:Script>

<s:VGroup>
     <s:DropDownList id="list" requireSelection="true" />

     <s:Label id="listSelectedItem" text="{list.selectedItem}" />
     <s:Label id="listSelectedIndex" text="{list.selectedIndex}" />

     <s:Button label="Flip" click="flipLast()" />
</s:VGroup>
</s:Application>

场景1：dataProvider已更新，但selectedIndex相同。在启动时：[listSelectedItem = Flex，listSelectedIndex = 1]。单击翻转：dataProvider已更新，但仍[listSelectedItem = Flex，listSelectedIndex = 1]。

场景2：dataProvider已更新，selectedIndex也已更新。在启动时：[listSelectedItem = Flex，listSelectedIndex = 1]。从列表中选择Air：[listSelectedItem = Air，listSelectedIndex = 2]。单击翻转：dataProvider已更新，但仍[listSelectedItem = Catalyst，listSelectedIndex = 1]。

在我看来，selectedItem是由selectedIndex驱动的。 selectedItem仅在selectedIndex更新时更新。当dataProvider更新时，不应该更新selectedItem吗？是否绑定到selectedItem有缺陷？

Answer 1

也许你认为它被打破是对的..我不会对此作出判断。您的问题的修复非常简单，更改翻转功能以重置所选索引，从而触发列表上的数据更改，并最终绑定到您的组件：

public function flipLast():void {
          list.selectedIndex = -1;
          if( last ) {
               list.dataProvider = dp1;
               list.selectedItem = "Flex";
          } else {
               list.dataProvider = dp2;
               list.selectedItem = "Catalyst";        
          }
          last = !last;
     }

在dataProvider更改后，Flex Spark DropDownList selectedItem未更新

1 个答案: