{"id":1881,"date":"2016-01-02T21:59:48","date_gmt":"2016-01-03T02:59:48","guid":{"rendered":"http:\/\/www.ikriv.com\/blog\/?p=1881"},"modified":"2016-01-02T21:59:48","modified_gmt":"2016-01-03T02:59:48","slug":"php-simplexml-is-broken-part-2","status":"publish","type":"post","link":"https:\/\/ikriv.com\/blog\/?p=1881","title":{"rendered":"PHP SimpleXml is Broken: Part 2"},"content":{"rendered":"

In a nuthsell, SimpleXMl has two things broken:<\/p>\n

1. Elements that represent “emtpy” tags evaluate to false<\/b>. This is weird design.
\n2. Other elements sometimes evaluate to false<\/b> due to bugs.<\/p>\n

I covered problem #1 in the previous post<\/a>. This post is about #2.<\/p>\n

Unfortunately, due to bugs in the SimpleXML parser, a non-empty element may evaluate to false<\/b>. No version I tested is completely bug-free, and the difference between correct and incorrect behavior may be as subtle as adding a space outside<\/b> the element in question.<\/p>\n

The code I use for testing is along these lines:<\/p>\n

<\/p>\n

$xml = $xml = simplexml_load_string($text);\n$node = $xml->xpath($xpath)[0];\nif<\/b> ($node) echo \"Evaluates to true!\"; else<\/b> echo \"Evaluates to false!\";<\/pre>\n
<\/code><\/p>\n
Here are the test results:<\/p>\n\n\n\n\n\n\n\n\n
$text<\/th>\n$xpath<\/th>\nResult<\/th>\nBoolean value<\/th>\n<\/tr>\n
<root><b>text<\/b><\/root><\/td>\n\/root\/b<\/td>\n<b>text<\/b><\/td>\nPHP 5.4.4 – true
\nPHP 5.4.45 – true
\nPHP 5.6.15 – true<\/td>\n<\/tr>\n
<root><a\/><b>text<\/b><\/root><\/td>\n\/root\/b<\/td>\n<b>text<\/b><\/td>\nPHP 5.4.4 – false<\/font>
\nPHP 5.4.45 – true
\nPHP 5.6.15 – true<\/td>\n<\/tr>\n
<root><a\/><b>text<\/b> <\/root>
\nnote extra space before<\/i> “<\/root>”<\/font><\/td>\n		\/root\/b<\/td>\n<b>text<\/b><\/td>\nPHP 5.4.4 – false
\nPHP 5.4.45 – false<\/font>
\nPHP 5.6.15 – true<\/td>\n<\/tr>\n
<x:root xmlns:x=”urn:q”><a \/><\/x:root>
\nsame as the first one, only with a namespace<\/i><\/font><\/td>\n		\/x:root<\/td>\n<?xml version=”1.0″?>
\n<x:root xmlns:x=”urn:q”><a\/><\/x:root><\/td>\n		PHP 5.4.4 – true
\nPHP 5.4.45 – true
\nPHP 5.6.15 – true<\/td>\n<\/tr>\n
<x:root xmlns:x=”urn:q”><x:a \/><\/x:root>
\nsame as previous, but using <x:a \/> instead of lt;a \/><\/i><\/font><\/td>\n		\/x:root<\/td>\n<?xml version=”1.0″?>
\n<x:root xmlns:x=”urn:q”><x:a\/><\/x:root><\/td>\n		PHP 5.4.4 – false
\nPHP 5.4.45 – false
\nPHP 5.6.15 – false<\/font><\/td>\n<\/tr>\n
<x:root xmlns:x=”urn:q”><x:b>text<\/x:b><\/x:root><\/td>\n\/x:root<\/td>\n<?xml version=”1.0″?>
\n<x:root xmlns:x=”urn:q”><x:b>text<\/x:b><\/x:root><\/td>\n		PHP 5.4.4 – false
\nPHP 5.4.45 – false
\nPHP 5.6.15 – false<\/font><\/td>\n<\/tr>\n<\/table>\n
I believe evaluating non-null objects to false<\/b> was not a good idea in the first place, but worse yet, PHP cannot really do it right, so the result of if ($node)<\/b> check is never reliable.<\/p>\n","protected":false},"excerpt":{"rendered":"
In a nuthsell, SimpleXMl has two things broken: 1. Elements that represent “emtpy” tags evaluate to false. This is weird design. 2. Other elements sometimes evaluate to false due to […]<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"Layout":"","footnotes":""},"categories":[5,15],"tags":[],"class_list":["entry","author-ikriv","post-1881","post","type-post","status-publish","format-standard","category-dev","category-webdev"],"_links":{"self":[{"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1881","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1881"}],"version-history":[{"count":0,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/1881\/revisions"}],"wp:attachment":[{"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1881"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1881"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1881"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}