Demo of PHP workaround for large integers in JSON data responses

json-int.php

<?php
/* Demonstration of problem with large integers in JSON, and
   a couple options for dealing with them as strings instead.

   ref:
   * http://php.net/manual/en/function.json-decode.php
   * http://stackoverflow.com/questions/2907806/handling-big-user-ids-returned-by-fql-in-php
*/

$json = <<<EOT
{
   "foo" : "bar",
   "small" : "123456",
   "large" : 200000000000009093302
}
EOT;
print "Original JSON data:\n$json\n";

// try normal JSON decode
$obj = json_decode ($json);
print "\nOriginal JSON decode results:\n";
var_dump ($obj);

if (version_compare(PHP_VERSION, '5.4.0', '>=')) {
    // if on PHP 5.4 or newer, use JSON "bigint" option
    $obj = json_decode ($json, false, 512, JSON_BIGINT_AS_STRING);
    print "\nJSON BIGINT decode (PHP 5.4+): \n";
    var_dump ($obj);
} else {
    // otherwise try workaround (convert number to string first)
    $json2 = fixJson ($json);
    $obj = json_decode ($json2);
    print "\nFixed JSON data:\n$json2\n";
    print "\nFixed JSON decode: \n";
    var_dump ($obj);
}

/* fixJson - work around large integer issue by adding quotes around
   any large numeric values - causes them to be interpreted as strings
*/
function fixJson ($json) {
    return (preg_replace ('/:\s?(\d{14,})/', ': "${1}"', $json));
}

1. The workaround for PHP 5 should not be needed nowadays.
2. Your approach completely disregards arrays of integer or integers in arrays.

But since a major oversight on PHP's part is that browsers don't choke on integers starting with BigInt (64 bits), but before that (53 bits). So my code is trying to remedy that.

Trying to use regular expression functions on JSON strings is almost as futile as using them on HTML. So my approach is to assume PHP is current and handle the decoded array:

function fix_large_int(&$value)
 {
  if (is_int($value) && $value > 9007199254740991)
    $value = strval($value);
 }
$json_arr = json_decode($json_str, flags: JSON_BIGINT_AS_STRING | JSON_OBJECT_AS_ARRAY);
echo('before: ' . json_encode($json_arr) . '<br />' . PHP_EOL);
array_walk_recursive($json_arr, 'fix_large_int');
echo('after:  ' . json_encode($json_arr) . '<br />' . PHP_EOL);

The number 9007199254740991 is what JavaScript has as its Number.MAX_SAFE_INTEGER value. Read about that here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/MAX_SAFE_INTEGER