PHP: XML エラーの対応

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 message や line、 column (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

<?php
libxml_use_internal_errors(true);
$sxe = simplexml_load_string("<?xml version='1.0'><broken><xml></broken>");
if ($sxe === false) {
    echo "Failed loading XML\n";
    foreach(libxml_get_errors() as $error) {
        echo "\t", $error->message;
    }
}
?>

上の例の出力は以下となります。

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

参考

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User Contributed Notes 3 notes

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openbip at gmail dot com ¶

14 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) {"

down

1337 at netapp dot com ¶

9 years ago

If you need to process the content of your broken XML-doc you might find this interesting. It has blown past a few simple corruptions for me.
http://php.net/manual/en/class.domdocument.php#domdocument.props.recover

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tuxedobob ¶

10 years 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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