Using php preg_replace to parse out target double quotes in JSON string

Question

I've been beating my head on this one, and can't figure out a regexp to accomplish the following:

Input string (this is JSON data surrounded by lots of other JSON):

$string=..."natural_order":"12"...

where 12 could also be a decimal like "1.2", or could be larger like 1288 or 1.288.

Desired string:

..."natural_order":12...

Using php preg_replace, so far I've gotten:

preg_replace('/[^natural_order:]+"/', '', $string);

but only returns:

"12"

Any thoughts are greatly appreciated!

preg_replace is for modifying the target string. To extract something you would need preg_match. stackoverflow.com/questions/5762739/… — mario
– mario, Commented Aug 11, 2011 at 4:11

deceze · Accepted Answer · 2011-08-11 03:58:31Z

2

Instead of tricky regexen, I'd suggest something along these lines:

$array = json_decode($string, true);
array_walk_recursive($array, function (&$value, $key) {
    if ($key == 'natural_order') {
        $value = strpos($value, '.') ? (float)$value : (int)$value;
    }
});
$string = json_encode($array);

answered Aug 11, 2011 at 3:58

deceze♦

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3 Comments

OverZealous Over a year ago

Yeah, that's the thing I didn't want to write out... ;-)

deceze Over a year ago

@Over I think this was faster to write out than trying to mind bend the right regex... ;)

OverZealous Over a year ago

Of note, anonymous functions (AKA closures) require PHP 5.3 or newer. But that can be rewritten using the old-style callbacks.

OverZealous · Accepted Answer · 2011-08-11 03:58:00Z

0

I can think of two solutions. The first, which I won't bother writing out, would be to decode the JSON using json_decode, correct the values by parsing them into ints, and re-encoding the string.

The second is to continue down your path. However, JSON is a fairly complicated string, and can't be reliably parsed using just a regex. If you are confident that the pattern "natural_order":"value" won't show up somewhere else, you could try this:

$result = preg_replace('/"natural_order"\s*\:\s*"([-+]?[0-9]*\.?[0-9]+)"/', '"natural_order":$1', $string);

This should match any encapsulated key, followed by a colon, followed by an encapsulated valid floating point number. There's also escapes in case there are spaces around the colon.

answered Aug 11, 2011 at 3:58

OverZealous

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1 Comment

OverZealous Over a year ago

I updated my example. I had an extra ` \ ` hiding in the replacement string.

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