check for a JSON string inside of a larger string in PHP

Question

Here is an example of a log file entry:

[22-Aug-2017 16:19:58 America/New_York] WP_Community_Events::maybe_log_events_response: Valid response received. Details: {"api_url":"https:\/\/api.wordpress.org\/events\/1.0\/","request_args":{"body":{"number":5,"ip":"192.168.99.0","locale":"en_GB","timezone":"America\/New_York"}},"response_code":200,"response_body":{"location":{"ip":"47.197.97.47"},"events":"5 events trimmed."}}

The {"api_url":"https:\/\/api.wordpress.... portion is valid JSON, but obviously the entire string itself (the log entry line) isn't. I'm hitting a wall with a way to essentially pull out that JSON without messing up any other part of the string.

Looks like you can just cut everything before the first brace, and everything after the last brace. — Alex Howansky, Aug 01 '18 at 18:08
JSON is coming after `Details:` I suppose. So that's a hint. — nice_dev, Aug 01 '18 at 18:09
this was an _example_. it won't always have "details" in front (or anything else for that matter) — Norcross, Aug 01 '18 at 18:55

dmotors · Accepted Answer · 2018-08-01T19:34:58.463

Use preg_match_all to find all the JSON and store it into an array like so:

$text = '[22-Aug-2017 16:19:58 America/New_York] WP_Community_Events::maybe_log_events_response: Valid response received. Details: {"api_url":"https:\/\/api.wordpress.org\/events\/1.0\/","request_args":{"body":{"number":5,"ip":"192.168.99.0","locale":"en_GB","timezone":"America\/New_York"}},"response_code":200,"response_body":{"location":{"ip":"47.197.97.47"},"events":"5 events trimmed."}}';

preg_match_all('/\{(?:[^{}]|(?R))*\}/x', $text, $matches);

echo '<pre>';
print_r($matches[0]);

This yields:

Array
(
    [0] => {"api_url":"https:\/\/api.wordpress.org\/events\/1.0\/","request_args":{"body":{"number":5,"ip":"192.168.99.0","locale":"en_GB","timezone":"America\/New_York"}},"response_code":200,"response_body":{"location":{"ip":"47.197.97.47"},"events":"5 events trimmed."}}
)

You can read up more from: Extracting the JSON string from given text

OR if you want the opposite and remove the JSON out and keep the string then you can use preg_replace to do this:

$text = '[22-Aug-2017 16:19:58 America/New_York] WP_Community_Events::maybe_log_events_response: Valid response received. Details: {"api_url":"https:\/\/api.wordpress.org\/events\/1.0\/","request_args":{"body":{"number":5,"ip":"192.168.99.0","locale":"en_GB","timezone":"America\/New_York"}},"response_code":200,"response_body":{"location":{"ip":"47.197.97.47"},"events":"5 events trimmed."}}';

$cleantext = preg_replace('~\{(?:[^{}]|(?R))*\}~', '', $text);

echo $cleantext;

Credit from PHP: How to extract JSON strings out of a string dump

This yields:

[22-Aug-2017 16:19:58 America/New_York] WP_Community_Events::maybe_log_events_response: Valid response received. Details:

Jason Grim · Answer 2 · 2018-08-01T18:41:57.710

1

You could try to get the start and end of the the json object and decode it. If there isn't a json decode error then you're good. This assumes that the characters { and } are only used in the json body.

function checkIfStringHasValidJson($string)
{
    $start = strpos($string, '{');
    $end = strrpos($string, '}');
    $json = substr($string, $start, $end);
    json_decode($json);
    return json_last_error() === JSON_ERROR_NONE;
}

edited Aug 01 '18 at 18:41

answered Aug 01 '18 at 18:16

Jason Grim

413
4
7

wanted to say this also worked, but the preg_match_all will get all of them (if more than one exist) – Norcross Aug 02 '18 at 13:57
@Norcross Makes sense, I assume there was just one object and was intentionally keeping it light. Glad you have a solution! – Jason Grim Aug 03 '18 at 06:15
Actually it is $end + 1 – Sorin Trimbitas Aug 14 '23 at 19:38

score 0 · Answer 3 · answered Aug 01 '18 at 18:13

Simply remove everything from the string before and including the given substring of "Details:":

$s = '[22-Aug-2017 16:19:58 America/New_York] WP_Community_Events::maybe_log_events_response: Valid response received. Details: {"api_url":"https:\/\/api.wordpress.org\/events\/1.0\/","request_args":{"body":{"number":5,"ip":"192.168.99.0","locale":"en_GB","timezone":"America\/New_York"}},"response_code":200,"response_body":{"location":{"ip":"47.197.97.47"},"events":"5 events trimmed."}}';
$out = str_replace('Details: ', '', strstr($s, 'Details:'));
echo var_export(json_decode($out));

check for a JSON string inside of a larger string in PHP

3 Answers3