{"id":27,"date":"2008-07-03T15:37:53","date_gmt":"2008-07-03T14:37:53","guid":{"rendered":"https:\/\/ridgesolutions.ie\/?p=27"},"modified":"2009-01-12T19:39:13","modified_gmt":"2009-01-12T18:39:13","slug":"xpath-with-adobe-actionscript-3","status":"publish","type":"post","link":"https:\/\/www.ridgesolutions.ie\/index.php\/2008\/07\/03\/xpath-with-adobe-actionscript-3\/","title":{"rendered":"XPath with Adobe ActionScript 3"},"content":{"rendered":"

While working on a\u00a0custom\u00a0XML data-driven content management system in ActionScript 3, we wanted to have\u00a0our XML content meta-data reference the actual XML content data by means of\u00a0XPath expressions – hence we needed some half decent XPath support within AS3.<\/p>\n

\u00a0<\/p>\n

AS3 has quite good XML support, however its support for XPath expressions and queries is not much to write home about at all!\u00a0\u00a0So instead, we have been using memorphic’s open source XPath implementation<\/a>\u00a0with much success.\u00a0 It is easy to install\u00a0& use, and it does a good job at implementing the majority of the XPath standard.<\/p>\n

\u00a0<\/p>\n

To use it, first download it and extract the src\\memorphic folder to somewhere on your path.\u00a0\u00a0Then import the XPath support to your AS3\u00a0code as follows:<\/p>\n

\u00a0<\/p>\n

\u00a0import memorphic.xpath.parser.*;\r\n\u00a0import memorphic.xpath.XPathQuery;<\/pre>\n
\u00a0<\/p>\n
To execute a query just\u00a0declare an XPathQuery object and call the exec() method\u00a0which returns\u00a0an ‘XMLList’ of matches:<\/p>\n
\u00a0<\/p>\n
\/\/ Get a list of the 'News' Items..<\/pre>\n
var myQuery:XPathQuery =<\/pre>\n
new XPathQuery(\"\/Content\/ContentData\/ContentItemList[@name='news']\");<\/pre>\n
\u00a0<\/pre>\n
\/\/ execute the statement on\u00a0the XML object and get the result<\/pre>\n
var result:XMLList = myQuery.exec(_xml);<\/pre>\n
\u00a0<\/p>\n
Quite refreshingly straightforward really.<\/p>\n
\u00a0<\/p>\n
One thing to look out for, and which caused a\u00a0lot of head-scratching for a while is that memorphic executes the XPath expression against a _copy_ of the provided XML tree, and the returned nodes belong to that tree and not the original – hence if you later modify any of these nodes, it is the copy that is modified and not the original XML tree, this was not really spelled out in any of the documentation.<\/p>\n
\u00a0<\/p>\n
For us, it was very important that this was not the case, so we got around the problem by just modifying the query code as follows:<\/p>\n
\u00a0<\/p>\n
within the definition of the function execRoot() in the file:<\/p>\n
\u00a0<\/p>\n
memorphic\\xpath\\model\\QueryRoot.as<\/pre>\n
\u00a0<\/p>\n
we changed:<\/p>\n
\u00a0<\/p>\n
contextNode.appendChild(xmlRoot.copy());<\/pre>\n
to:<\/p>\n
contextNode.appendChild(xmlRoot);<\/pre>\n
With no ill effects (yet!).<\/p>\n","protected":false},"excerpt":{"rendered":"
While working on a\u00a0custom\u00a0XML data-driven content management system in ActionScript 3, we wanted to have\u00a0our XML content meta-data reference the actual XML content data by means of\u00a0XPath expressions – hence we needed some half decent XPath support within AS3. \u00a0 AS3 has quite good XML support, however its support for XPath expressions and queries is […]<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[19,36,35],"class_list":["post-27","post","type-post","status-publish","format-standard","hentry","category-tech-stuff","tag-as3","tag-xml","tag-xpath"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t