json_encode() expects parameter 2 to be long, string given

Question

I'm trying to return a JSON from a REST Service using this code:

$categories = $categoriesController->listAll();
if($categories){
   header($_SERVER["SERVER_PROTOCOL"] . " 200 OK");
   header("Content-Type: application/json");
   echo json_encode($categories,JSON_PRETTY_PRINT);
}else{

}

But I get this error:

json_encode() expects parameter 2 to be long, string given

I've seen several examples use the exact same code so I don't understand why i'm getting this issue. I'd appreciate some help with this problem. Thanks :)

Answer 1

JSON_PRETTY_PRINT was introduced in PHP 5.4.0.

If you would like to make your code more readable in earlier versions of PHP, use these constants instead of their numerical values. Notice that I put the version each became available--if you use an option in an earlier version of PHP, don't expect it to work.

<?php
   // json_encode() options
   define('JSON_HEX_TAG',                1);    // Since PHP 5.3.0
   define('JSON_HEX_AMP',                2);    // Since PHP 5.3.0
   define('JSON_HEX_APOS',               4);    // Since PHP 5.3.0
   define('JSON_HEX_QUOT',               8);    // Since PHP 5.3.0
   define('JSON_FORCE_OBJECT',           16);   // Since PHP 5.3.0
   define('JSON_NUMERIC_CHECK',          32);   // Since PHP 5.3.3
   define('JSON_UNESCAPED_SLASHES',      64);   // Since PHP 5.4.0
   define('JSON_PRETTY_PRINT',           128);  // Since PHP 5.4.0
   define('JSON_UNESCAPED_UNICODE',      256);  // Since PHP 5.4.0

   // json_decode() options
   define('JSON_OBJECT_AS_ARRAY',        1);    // Since PHP 5.4.0
   define('JSON_BIGINT_AS_STRING',       2);    // Since PHP 5.4.0
   define('JSON_PARSE_JAVASCRIPT',       4);    // upgrade.php

   // json_last_error() error codes
   define('JSON_ERROR_NONE',             0);    // Since PHP 5.3.0
   define('JSON_ERROR_DEPTH',            1);    // Since PHP 5.3.0
   define('JSON_ERROR_STATE_MISMATCH',   2);    // Since PHP 5.3.0
   define('JSON_ERROR_CTRL_CHAR',        3);    // Since PHP 5.3.0
   define('JSON_ERROR_SYNTAX',           4);    // Since PHP 5.3.0
   define('JSON_ERROR_UTF8',             5);    // Since PHP 5.3.3
   define('JSON_ERROR_RECURSION',        6);    // Since PHP 5.5.0
   define('JSON_ERROR_INF_OR_NAN',       7);    // Since PHP 5.5.0
   define('JSON_ERROR_UNSUPPORTED_TYPE', 8);    // Since PHP 5.5.0
?>