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我需要在组合框的 selectedItem 和 valueobject 的字段之一中启用两种方式的数据绑定。我正在使用 @{variable name} 构造。

它以一种方式工作 - 当 valueobject 的字段更改时，组合框的 selectedItem 正在更新。但是除非我明确处理组合框的更改事件，否则反向不起作用。@ 是否有任何理由无法按预期工作。

在下面的代码片段中，我试图将 OrderInfo.billingName 绑定到 combo1.selectedItem。

第一个用例：OrderInfo.billingName 的初始值设置为 combo1.selectedItem

第二个用例：如果 OrderInfo.billingName 值在两者之间发生变化，那么 combo1.selectedItem 也会更新

第三个用例：当用户从 combo1 中选择某个值时，除非我处理更改事件，否则它不会被分配给 OrderInfo.billingName。

[Bindable]

public class OrderInfo {

        public var billingName:String ; //This field is bindable to combo1’s selectedItem
        public var billingAddress:String;
        public var billingCity:String;
        public var billingState:String;
        public var billingZip:String;
        public var cardType:String;
        public var cardNumber:String;
        public var cardExpirationMonth:String;
        public var cardExpirationYear:String;
        public var deliveryDate:Date;

        public function OrderInfo() {
        }
        public function toString ():String {
              return "I am OrderInfo : " + this.billingName + this.billingCity;
        }
  }

<?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" minWidth="955" 
                 minHeight="600"
                 initialize="application1_initializeHandler(event)">
  <fx:Script>
        <![CDATA[
              import mx.binding.utils.BindingUtils;
              import mx.collections.ArrayCollection;
              import mx.controls.Alert;
              import mx.events.FlexEvent;
              import mx.events.IndexChangedEvent;
              import mx.utils.ObjectUtil;

              import spark.events.IndexChangeEvent;
              [Bindable]
              public var dp:ArrayCollection = new ArrayCollection (
                    [     {Id:'one', Amount:1000},
                          {Id:'two', Amount:2000},
                          {Id:'three', Amount:3000}
                    ]
              );
              [Bindable]
              public var orderInfo:OrderInfo = new OrderInfo();
              protected function application1_initializeHandler(event:FlexEvent):void
              {
                    //Initial value of the field .. this could be coming via database
                    orderInfo.billingName = 'one';
              }


              protected function combo1_changeHandler(event:IndexChangeEvent):void
              {
                    orderInfo.billingName = (((event.currentTarget as 
                    ComboBox).selectedItem as Object).Id); //??
              }

              protected function button1_clickHandler(event:Event):void
              {
                    mx.controls.Alert.show(ObjectUtil.toString(orderInfo));
              }

              protected function button2_clickHandler(event:Event):void
              {
                    // Some backend process changed the value object
                    orderInfo.billingName = 'three';
              }
        ]]>
  </fx:Script>

  <s:ComboBox id="combo1" x="81" y="65"
                    dataProvider="{dp}"
                    labelField="Id"
                    selectedItem="@{orderInfo.billingName}"
                    change="combo1_changeHandler(event)"
                    />

  <s:Button label="Get OrderInfo Object Snapshot" click="button1_clickHandler(event)" 
   x="273" y="176"/>
  <s:Button label="Change OrderInfo Object" click="button2_clickHandler(event)" 
   x="52"    y="176"/>

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1 回答 1

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我也在考虑让这个功能正常工作。我认为问题在于绑定的是什么。该selectedItem属性需要一个类型的对象，*这意味着arrayCollection它所绑定的项目。所以尝试传递一个或这些对象

({Id:'one', Amount:1000},{Id:'two', Amount:2000},{Id:'three', Amount:3000})

到selectedItem属性而不是字符串。

于 2013-07-23T08:18:14.403 回答