检查 XML 值是否在 AS3 数组中

Question

我有一些以下格式的 XML。

 <user uid="0001">
    <FirstName>John</FirstName>
    <LastName>Smith</LastName>
    <ImagePath>images/0001.jpg</ImagePath>
    <flightno>GS1234</flightno>
</user>
<user uid="0002">
    <FirstName>Luke</FirstName>
    <LastName>Dixon</LastName>
    <ImagePath>images/0002.jpg</ImagePath>
    <flightno>TD1234</flightno>
</user>
<user uid="0003">
    <FirstName>Paul</FirstName>
    <LastName>Kerr</LastName>
    <ImagePath>images/0003.jpg</ImagePath>
    <flightno>GS1234</flightno>
</user>

这是一个小样本，其中有 100 个。

我使用 E4x 过滤来过滤另一组生成 as3 数组的 XML 数据。该数组包含一些航班号（例如：[GS1234,PB7367,TD1234]。

我想知道如何过滤我的 XML（如上所示）以仅显示在 AS3 数组中存在“flightno”的用户。

我猜它是某种 E4X 查询，但我似乎无法正确理解！

谢谢！

Answer 1

// Don't mind me using this trick with inline XML, it's not the point.
// It's here just to make it possible to copy and paste code 
// with multiline XML sample.The actual solution is a one-liner below.
var usersXML:XML = new XML(<x><![CDATA[
<data>
<user uid="0001">
    <FirstName>John</FirstName>
    <LastName>Smith</LastName>
    <ImagePath>images/0001.jpg</ImagePath>
    <flightno>GS1234567</flightno>
</user>
<user uid="0002">
    <FirstName>Luke</FirstName>
    <LastName>Dixon</LastName>
    <ImagePath>images/0002.jpg</ImagePath>
    <flightno>TD1234</flightno>
</user>
<user uid="0003">
    <FirstName>Paul</FirstName>
    <LastName>Kerr</LastName>
    <ImagePath>images/0003.jpg</ImagePath>
    <flightno>GS1234</flightno>
</user>
</data>
]]></x>.toString());

// once again, the way I create sample departingXML 
// is not important, it's just for copying and pasting into IDE.
var departingXML:XML = new XML(<x><![CDATA[
<flights>
    <flight>
        <number>GS1234</number>
        <date>10/11/2015</date>
        <time>1440</time>
    </flight>
    <flight>
        <number>TD1234</number>
        <date>10/11/2015</date>
        <time>1450</time>
    </flight>
</flights>
]]></x>.toString());


// 1. create filter array
var flightNoArray:Array = [];
departingXML.flight.number.(flightNoArray.push(toString()));

trace(flightNoArray); // GS1234,TD1234
trace(typeof(flightNoArray[0])); // string

// 2. filter users:
var list:XMLList = usersXML.user.(flightNoArray.indexOf(flightno.toString()) >= 0);

trace(list); // traces users 0002 and 0003

我不会称其为高效或至少可读性。

// Note: this line is somewhat queer and I don't like it,

departingXML.flight.number.(flightNoArray.push(toString()));

// but this is the only way I can now think of to get and array 
// of strings from an XMLList nodes without a loop.
// I would advise to use a readable and simple loop instead.

• usersXML.user -- 这将为您提供一个 XMLList，其中所有节点都名为“user”
• usersXML.user.(some condition) -- 这会过滤给定条件的用户节点的 XMLList
• flightNoArray.indexOf(flightno.toString()) >= 0 -- 这是一个过滤条件
• flightno.toString() -- 在 flightno child 中得到一个字符串
• REFERENCE: Traversing XML structures。
• Explanation of the search trick 在上面的注释中。

更新：在 cmets 中发现，过滤器数组的填充方式也导致了问题。下面的代码演示了更多的 E4X。

这是过滤器列表的创建方式以及实际发生的情况：

// once again, the way I create sample departingXML 
// is just for the sake of copying and pasting, it's not related to solution.
var departingXML:XML = new XML(<x><![CDATA[
<flights>
    <flight>
        <number>GS1234</number>
        <date>10/11/2015</date>
        <time>1440</time>
    </flight>
    <flight>
        <number>TD1234</number>
        <date>10/11/2015</date>
        <time>1450</time>
    </flight>
</flights>
]]></x>.toString());

// the way it was done before
var flightNoArray: Array = []; 
for each(var num: XML in departingXML.flight) { 
    flightNoArray.push(num.number);

    // WARNING! num.number is an XMLList! It s NOT a string.
    // Addressing nodes by name ALWAYS gets you an XMLList, 
    // even if there's only one node with that name
    // Hence, `flightNoArray.indexOf("string")` could not possibly work, 
    // as there are lists inside of the array, not strings.


    // We can check if this is a fact:
    trace(flash.utils.getQualifiedClassName(flightNoArray[flightNoArray.length-1])); 
    // (traces XMLList)

    // Or this way (note toXMLString() method)
    trace(flightNoArray[flightNoArray.length-1].toXMLString()); 
    // (traces <number>GS1234</number>)
} 

trace(flightNoArray); 

trace(flightNoArray); 跟踪 GS1234,TD1234 因为这是 toString() 方法适用于 xml 节点的方式——它为您获取文本，即在内部。这就是为什么有一个特殊的方法 toXMLString()，它可以得到一个节点的字符串表示。