从 MXML 初始化集合 [英] Initializing a collection from MXML

问题描述

先生们，

如何在 Flex/Actionscript 中从 MXML 初始化集合实例?

How does one initialize a collection instance from MXML in Flex/Actionscript?

背景

假设:

• 我有三个数字名称列表对.
• 每个列表的内容从不更改，但我可能想添加新的将来列出.
• 用户可以选择哪个列表使用.

我知道怎么做使用 MXML 来定义/初始化一个Flex UI 组件，但这就是我的 XML 经验的全部内容.

I know how to use MXML to define/initialize a Flex UI component, but that is the full extent of my XML experience.

问题

如何编写 XML 声明和 Actionscript 类的组合，以便我可以从 XML 初始化我的三个列表中的每一个?

How do I write a combination of XML declarations and Actionscript classes such that I can initialize each of my three lists from XML?

请注意，我不会尝试使用各种数字-名称对填充 Flex UI 元素(例如 DataGrid).我只是想将数据读入一个普通的旧香草集合.(一旦我的集合被初始化，我就可以在空闲时填充 DataGrids 或任何东西.)我找不到任何关于如何解决这个超级简单案例的文档.文档都假设我正在尝试做一些更复杂的事情，例如访问远程数据库，这会极大地混淆问题.

Please note that I am not trying to populate a Flex UI element (such as a DataGrid) with the various number-name pairs. I'm just trying to read the data into a plain old vanilla collection. (Once I've got my collections initialized, I can populate DataGrids or whatever at my leisure.) I can't find any documentation of how to address this super-simple case. The documentation all assumes that I'm trying to do something much more complicated, such as accessing a remote database, which confuses the issue tremendously.

谢谢！:-)

德克萨斯州吉姆普拉蒙登

Jim Plamondon, Texas

推荐答案

有几种方法可以做到这一点:

There's a few ways you can do this:

样本数据集:

<?xml version="1.0" encoding="UTF-8"?>
<events type="array">
    <event>
        <date>12-50-99</date>
        <title>Event A</title>
        <location>San Diego, CA</location>
    </event>
    <event>
        <date>12-50-99</date>
        <title>Event B</title>
        <location>Healdsburg, CA</location>
    </event>
</events>

弹性 4

XML 声明

以下是将数据导入 XML 或 ArrayCollection 的 3 种方法，您可以将这两种方法传递给您的数据提供者.

Flex 4

XML Declarations

Below are 3 ways to get data into XML or an ArrayCollection, both of which you can pass to your data provider.

<?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">

    <fx:Declarations>
        <fx:XML id="data" source="events.xml"/>

        <fx:XML id="data2">
            <event>
                <date>12-50-99</date>
                <title>Event A</title>
                <location>San Diego, CA</location>
            </event>
            <event>
                <date>12-50-99</date>
                <title>Event B</title>
                <location>Healdsburg, CA</location>
            </event>
        </fx:XML>

        <fx:Declarations>
            <mx:ArrayCollection id="data3">
                <fx:Object date="12-50-99" title="Event A" location="San Diego, CA"/>
                <fx:Object date="12-50-99" title="Event B" location="Healdsburg, CA"/>
            </mx:ArrayCollection>
        </fx:Declarations>
    </fx:Declarations>

    <!-- then your views -->
    <mx:Button/>
</s:Application>

Flex 3 的工作原理相同，但您只需删除 <fx:Declarations/> 标签.

Flex 3 works the same, but you just remove the <fx:Declarations/> tags.

如果您希望数据是动态的，我只需在您视图中的 <mx:Script/> 块中为您的 ArrayCollection 或 XMLListCollection 创建一个属性，例如 [Bindable] public var myData:ArrayCollection;，并通过 XML 将数据加载到其中.通过将您的数据保持在外部(而不是将数据硬编码/嵌入到 MXML 中)，您无需重新编译，而且添加越来越多的数据也变得更加容易.

If you want the data to be dynamic, I would just create a property for your ArrayCollection or XMLListCollection in the <mx:Script/> block in your view, say [Bindable] public var myData:ArrayCollection;, and load the data into that via XML. By keeping your data external (not hardcoding/embedding data into MXML), you don't have to recompile, and it's easier to add more and more.

为此，您需要使用 URLRequest 或 HTTPService.HTTPService 基本上是一个围绕 URLRequest 的 MXML 包装器.

In order to do that, you'd either need to use URLRequest or HTTPService. HTTPService is basically an MXML wrapper around the URLRequest.

类似于这个伪代码:

<?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"
    initialize="loadData()">
    <fx:Script>

        import mx.collections.*;

        [Bindable] public var list1:IList;
        [Bindable] public var list2:IList;
        [Bindable] public var list3:IList;

        public function loadData():void
        {
            eventsService.load(); // loads, may take a few frames/seconds
        }

        public function updateData(result:Object, property:String):void
        {
            // this["list1"] = xml;
            this[property] = new XMLListCollection(result);
        }

    </fx:Script>

    <fx:Declarations>
        <mx:HTTPService id="eventsService"
            url="events.xml" 
            resultFormat="e4x"
            result="updateData(event.result, 'list1');"
            fault="trace('eventsService Error');"/>
    </fx:Declarations>

    <!-- then your views -->
    <mx:List dataProvider="{list1}"/>
</s:Application>

让我知道这是否有效.

这篇关于从 MXML 初始化集合的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！