XML エラーの対応

ドキュメント読み込み時の XML エラーに対処するのは非常にシンプルな作業です。 libxml の機能を使うと、 ドキュメント読み込み時のすべての XML エラーを抑制して後からそれを処理することができます。

libxml_get_errors() が返す libXMLError オブジェクトには、エラーについての messagelinecolumn (場所) といったプロパティが含まれます。

例1 壊れた XML 文字列の読み込み

$sxe simplexml_load_string("<?xml version='1.0'><broken><xml></broken>");
if (
$sxe === false) {
"Failed loading XML\n";
libxml_get_errors() as $error) {


Failed loading XML
    Blank needed here
    parsing XML declaration: '?>' expected
    Opening and ending tag mismatch: xml line 1 and broken
    Premature end of data in tag broken line 1

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User Contributed Notes 3 notes

openbip at gmail dot com
5 years ago
Note that "if (! $sxe) {" may give you a false-negative if the XML document was empty (e.g. "<root />").  In that case, $sxe will be:

object(SimpleXMLElement)#1 (0) {

which will evaluate to false, even though nothing technically went wrong.

Consider instead: "if ($sxe === false) {"
Jacob Tabak
5 years ago
If you are trying to load an XML string with some escaped and some unescaped ampersands, you can pre-parse the string to ecsape the unescaped ampersands without modifying the already escaped ones:
= preg_replace('/&[^; ]{0,6}.?/e', "((substr('\\0',-1) == ';') ? '\\0' : '&amp;'.substr('\\0',1))", $s);
6 months ago
Now that the /e modifier is considered deprecated in preg_replace, you can use a negative lookahead to replace unescaped ampersands with &amp; without throwing warnings:

$str = preg_replace('/&(?!;{6})/', '&amp;', $str);

You probably should have been doing this before /e was deprecated, actually.
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