{"id":1179,"date":"2011-01-07T16:16:05","date_gmt":"2011-01-07T21:16:05","guid":{"rendered":"http:\/\/www.lonhosford.com\/lonblog\/?p=1179"},"modified":"2015-07-31T18:25:51","modified_gmt":"2015-07-31T23:25:51","slug":"php-simplexml-load-xml-file-preserve-cdata-remove-whitespace-between-nodes-and-return-json","status":"publish","type":"post","link":"https:\/\/www.lonhosford.com\/lonblog\/2011\/01\/07\/php-simplexml-load-xml-file-preserve-cdata-remove-whitespace-between-nodes-and-return-json\/","title":{"rendered":"PHP SimpleXML: Load XML File, Preserve CDATA, Remove Whitespace Between Nodes and Return JSON"},"content":{"rendered":"

I needed to create an indented easy to read and edit XML file that a novice web owner could edit. This entailed having the nodes nicely indented so the user could find them easily. The XML file required CDATA nodes. \"\"The CDATA nodes I wanted on a separate line again so the user could easily find them. Finally I needed to send the loaded XML data in JSON format to the client side. <\/p>\n

I chose SimpleXML simplexml_load_file method<\/a> to handle the XML file and data. The problem with simplexml_load_file is that it ignores CDATA nodes. This is not immediately clear when reading the documentation. You do find references to the CDATA issue in the user comments. <\/p>\n

The documentation also provides a hint should you decide to explore the simplexml_load_file options argument<\/a>. Here you see the LIBXML_NOCDATA value which includes this explanation: “Merge CDATA as text nodes.” Using this option value converts the node containing the CDATA node into a text node using the container node name. Thus <\/p>\n

\r\n<info>\r\n\t<!&#91;CDATA&#91;<b>Help<\/b>&#93;&#93;>\r\n<\/info>\r\n<\/pre>\n
becomes<\/p>\n
\r\n<info>\r\n\t<b>Help<\/b>\r\n<\/info>\r\n<\/pre>\n
This is fine since the data returning to the client is in JSON format. Here is how the solution would look:<\/p>\n
\r\n$xml = simplexml_load_file($xml_filename, 'SimpleXMLElement', LIBXML_NOCDATA);\r\n<\/pre>\n
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\nThis solution creates another problem. The tabs and new line characters between the CDATA containing node are added to the new text node when converting to JSON. <\/p>\n
\r\n\\n\\t\\t\\t\\t<b>help<\/b>\r\n<\/pre>\n
Clearly, information between nodes is NOT data.  Since my goal was to have a nicely formatted XML file for a user to update manually, this created the need to strip the whitespace added. <\/p>\n
The approach I selected was to use a regular expression to remove the whitespace characters before and after the < > tag delimters  as follows:<\/p>\n
\r\n'~\\s*(<(&#91;^>]*)>[^<&#93;*<\/\\2>|<&#91;^>]*>)\\s*~','$1'\r\n<\/pre>\n
One caveat is that if you decide to include html in the cdata node, the regular expression removes the whitespace before and after those tags.<\/p>\n
Also is this needs to be applied before converting to SimpleXML. So I used file_get_contents<\/a> to load the xml data file, applied the regular expression and then converted to a SimpleXML object. <\/p>\n
The completed PHP script is as follows:<\/p>\n
\r\n<?php\r\n\/\/ The XML data file with whitespace such as tabs\r\n$xml_file = "user_formatted_xml_data.xml";\r\n\/\/ Load xml data.\r\n$xml = file_get_contents($xml_file);\r\n\/\/ Strip whitespace between xml tags\r\n$xml = preg_replace('~\\s*(<(&#91;^>]*)>[^<&#93;*<\/\\2>|<&#91;^>]*>)\\s*~','$1',$xml);\r\n\/\/ Convert CDATA into xml nodes.\r\n$xml = simplexml_load_string($xml,'SimpleXMLElement', LIBXML_NOCDATA);\r\n\/\/ Return JSON.\r\necho json_encode($xml);\r\n?>\r\n<\/pre>\n
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\nHere is a sample data file to try.<\/p>\n
\r\n<?xml version="1.0" encoding="UTF-8"?>\r\n<news_items>\r\n\t<news_item>\r\n\t\t<title>\r\n\t\t\t<!&#91;CDATA&#91;News item title #1 with <br\/>html added.&#93;&#93;>\r\n\t\t<\/title>\r\n\t\t<content>\r\n\t\t\t<!&#91;CDATA&#91;This is the <b>CDATA content<\/b> for news item<strong> #1 <\/strong> with some "html" included.&#93;&#93;>\r\n\t\t<\/content>\r\n\t<\/news_item>\r\n\t<news_item>\r\n\t\t<title>\r\n\t\t\t<!&#91;CDATA&#91;News item title #2 with <br\/>html added.&#93;&#93;>\r\n\t\t<\/title>\r\n\t\t<content>\r\n\t\t\t<!&#91;CDATA&#91;This is the <b>CDATA content<\/b> for news item<strong> #2 <\/strong> with some "html" included.&#93;&#93;>\r\n\t\t<\/content>\r\n\t<\/news_item>\r\n<\/news_items>\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"
I needed to create an indented easy to read and edit XML file that a novice web owner could edit. This entailed having the nodes nicely indented so the user could find them easily. The XML file required CDATA nodes. The CDATA nodes I wanted on a separate line again so the user could easily […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5],"tags":[61,57,62],"class_list":["post-1179","post","type-post","status-publish","format-standard","hentry","category-general","tag-json","tag-php-2","tag-xml"],"_links":{"self":[{"href":"https:\/\/www.lonhosford.com\/lonblog\/wp-json\/wp\/v2\/posts\/1179","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.lonhosford.com\/lonblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.lonhosford.com\/lonblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.lonhosford.com\/lonblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.lonhosford.com\/lonblog\/wp-json\/wp\/v2\/comments?post=1179"}],"version-history":[{"count":26,"href":"https:\/\/www.lonhosford.com\/lonblog\/wp-json\/wp\/v2\/posts\/1179\/revisions"}],"predecessor-version":[{"id":3693,"href":"https:\/\/www.lonhosford.com\/lonblog\/wp-json\/wp\/v2\/posts\/1179\/revisions\/3693"}],"wp:attachment":[{"href":"https:\/\/www.lonhosford.com\/lonblog\/wp-json\/wp\/v2\/media?parent=1179"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.lonhosford.com\/lonblog\/wp-json\/wp\/v2\/categories?post=1179"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.lonhosford.com\/lonblog\/wp-json\/wp\/v2\/tags?post=1179"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}