PHP REGEX: Remove/replace quotes within an XML attribute

Question

Please consider the following line from an XML file (generated from a third-party source):

<record ObTime="2017-05-10T23:30" data_value="Ocean Park "The Sea WX"  WA US" />

As you can see, the attribute data_value has quoted string inside the value, which causes XML validators to giggle and explode.

Any given XML file could have thousands of lines. Is there a way to apply REGEX to a whole file? And, what would the REGEX be to replace quotes with something more benign?

Answer 1

There might be other, and better, solutions, but this is how I made it works:

• Using preg_match_all with certain regex to capture all matches, and store them in an array $matches[0].
• The regex: (?<=data_value=").*(?=" \/>) will capture everything between data_value=" and " />), by making use of positive lookbehind and lookahead, precisely match the values of each of the data_value attributes.
• Loop through items in $matches[0] and we do the following:
  1. Replace every double qoutes string " with % [could be any other string, even blank, that doesn't cause further problems] in every single match, and store it in a temporary variable $str.
  2. Then replace the value of each match in the whole data string with the value of the modified version of the match, the $str string.

PHP code:
_{remember that because the data is xml tags, you need to use "view source" in order to see the output, alternatively, you can use var_dump instead of echo}

<?php
$data = '<record ObTime="2017-05-10T23:30" data_value="Ocean Park "The Sea WX"  WA US" />
<record ObTime="2017-11-10T23:30" data_value="Some Other "Demo Text"  In Here" />';

$data_valueVal = preg_match_all('#(?<=data_value=").*(?=" \/>)#i', $data, $matches);

foreach($matches[0] as $match) {
    $str = str_replace('"', "%", $match);
    $data = str_replace($match, $str, $data);
}
echo $data;
?>

---

Output:

<record ObTime="2017-05-10T23:30" data_value="Ocean Park %The Sea WX% WA US" /> <record ObTime="2017-11-10T23:30" data_value="Some Other %Demo Text% In Here" />

Answer 2

Using Regex below, you are able to match those double quotes separately for further modifications:

(?:="|"\s+(?:\w+="|\/>))(*SKIP)(?!)|"

By using (*SKIP)(?!) you force engine to jump over first side of alternation after each successful match.

Live demo

PHP code (removing quotes):

echo preg_replace('~(?:="|"\s+(?:\w+="|\/>))(*SKIP)(?!)|"~', '', $xml);