json_last_error

(PHP 5 >= 5.3.0)

json_last_errorReturns the last error occurred

Description

int json_last_error ( void )

Returns the last error (if any) occurred during the last JSON encoding/decoding.

Parameters

This function has no parameters.

Return Values

Returns an integer, the value can be one of the following constants:

JSON error codes
Constant Meaning Availability
JSON_ERROR_NONE No error has occurred  
JSON_ERROR_DEPTH The maximum stack depth has been exceeded  
JSON_ERROR_STATE_MISMATCH Invalid or malformed JSON  
JSON_ERROR_CTRL_CHAR Control character error, possibly incorrectly encoded  
JSON_ERROR_SYNTAX Syntax error  
JSON_ERROR_UTF8 Malformed UTF-8 characters, possibly incorrectly encoded PHP 5.3.3
JSON_ERROR_RECURSION One or more recursive references in the value to be encoded PHP 5.5.0
JSON_ERROR_INF_OR_NAN One or more NAN or INF values in the value to be encoded PHP 5.5.0
JSON_ERROR_UNSUPPORTED_TYPE A value of a type that cannot be encoded was given PHP 5.5.0

Examples

Example #1 json_last_error() example

<?php
// A valid json string
$json[] = '{"Organization": "PHP Documentation Team"}';

// An invalid json string which will cause an syntax 
// error, in this case we used ' instead of " for quotation
$json[] = "{'Organization': 'PHP Documentation Team'}";


foreach (
$json as $string) {
    echo 
'Decoding: ' $string;
    
json_decode($string);

    switch (
json_last_error()) {
        case 
JSON_ERROR_NONE:
            echo 
' - No errors';
        break;
        case 
JSON_ERROR_DEPTH:
            echo 
' - Maximum stack depth exceeded';
        break;
        case 
JSON_ERROR_STATE_MISMATCH:
            echo 
' - Underflow or the modes mismatch';
        break;
        case 
JSON_ERROR_CTRL_CHAR:
            echo 
' - Unexpected control character found';
        break;
        case 
JSON_ERROR_SYNTAX:
            echo 
' - Syntax error, malformed JSON';
        break;
        case 
JSON_ERROR_UTF8:
            echo 
' - Malformed UTF-8 characters, possibly incorrectly encoded';
        break;
        default:
            echo 
' - Unknown error';
        break;
    }

    echo 
PHP_EOL;
}
?>

The above example will output:

Decoding: {"Organization": "PHP Documentation Team"} - No errors
Decoding: {'Organization': 'PHP Documentation Team'} - Syntax error, malformed JSON

Example #2 json_last_error() with json_encode()

<?php
// An invalid UTF8 sequence
$text "\xB1\x31";

$json  json_encode($text);
$error json_last_error();

var_dump($json$error === JSON_ERROR_UTF8);
?>

The above example will output:

string(4) "null"
bool(true)

See Also

Коментарии

While this can obviously change between versions, the current error codes are as follows:

0 = JSON_ERROR_NONE
1 = JSON_ERROR_DEPTH
2 = JSON_ERROR_STATE_MISMATCH
3 = JSON_ERROR_CTRL_CHAR
4 = JSON_ERROR_SYNTAX
5 = JSON_ERROR_UTF8

I'm only posting these for people who may be trying to understand why specific JSON files are not being decoded. Please do not hard-code these numbers into an error handler routine.
2011-11-23 23:16:31
http://php5.kiev.ua/manual/ru/function.json-last-error.html
This is a quite simple and functional trick to validate JSON's strings.

<?php

   
function json_validate($string) {
        if (
is_string($string)) {
            @
json_decode($string);
            return (
json_last_error() === JSON_ERROR_NONE);
        }
        return 
false;
    }
    echo (
json_validate('{"test": "valid JSON"}')  ? "It's a JSON" "NOT is a JSON"); // prints 'It's a JSON'
   
echo (json_validate('{test: valid JSON}')  ? "It's a JSON" "NOT is a JSON"); // prints 'NOT is a JSON' due to missing quotes
   
echo (json_validate(array())  ? "It's a JSON" "NOT is a JSON"); // prints 'NOT is a JSON' due to a non-string argument
?>

Cheers
2014-01-30 20:32:09
http://php5.kiev.ua/manual/ru/function.json-last-error.html
I used this simple script, flicked from StackOverflow to escape from the function failing:

<?php
   
function utf8ize($d) {
        if (
is_array($d)) {
            foreach (
$d as $k => $v) {
               
$d[$k] = utf8ize($v);
            }
        } else if (
is_string ($d)) {
            return 
utf8_encode($d);
        }
        return 
$d;
    }
?>

Cheers,
Praveen Kumar!
2014-10-21 18:17:22
http://php5.kiev.ua/manual/ru/function.json-last-error.html
when json_decode a empty string, PHP7 will trigger an Syntax error:
<?php
json_decode
("");
var_dump(json_last_error(), json_last_error_msg());

// PHP 7
int(4)
string(12"Syntax error"

//  PHP 5
int(0)
string(8"No error"
2015-10-18 18:02:23
http://php5.kiev.ua/manual/ru/function.json-last-error.html
Автор:
Just adding this note since I had to code this for the actual values reference.

<?php

echo JSON_ERROR_NONE ' JSON_ERROR_NONE' '<br />';
echo 
JSON_ERROR_DEPTH ' JSON_ERROR_DEPTH' '<br />';
echo 
JSON_ERROR_STATE_MISMATCH ' JSON_ERROR_STATE_MISMATCH' '<br />';
echo 
JSON_ERROR_CTRL_CHAR ' JSON_ERROR_CTRL_CHAR' '<br />';
echo 
JSON_ERROR_SYNTAX ' JSON_ERROR_SYNTAX' '<br />';
echo 
JSON_ERROR_UTF8 ' JSON_ERROR_UTF8' '<br />';
echo 
JSON_ERROR_RECURSION ' JSON_ERROR_RECURSION' '<br />';
echo 
JSON_ERROR_INF_OR_NAN ' JSON_ERROR_INF_OR_NAN' '<br />';
echo 
JSON_ERROR_UNSUPPORTED_TYPE ' JSON_ERROR_UNSUPPORTED_TYPE' '<br />';

/*
The above outputs :
0 JSON_ERROR_NONE
1 JSON_ERROR_DEPTH
2 JSON_ERROR_STATE_MISMATCH
3 JSON_ERROR_CTRL_CHAR
4 JSON_ERROR_SYNTAX
5 JSON_ERROR_UTF8
6 JSON_ERROR_RECURSION
7 JSON_ERROR_INF_OR_NAN
8 JSON_ERROR_UNSUPPORTED_TYPE
*/

?>
2016-09-28 11:27:01
http://php5.kiev.ua/manual/ru/function.json-last-error.html
use this code with mb_convert_encoding, you can json_encode some corrupt UTF-8 chars

    function safe_json_encode($value, $options = 0, $depth = 512) {
        $encoded = json_encode($value, $options, $depth);
        if ($encoded === false && $value && json_last_error() == JSON_ERROR_UTF8) {
            $encoded = json_encode(utf8ize($value), $options, $depth);
        }
        return $encoded;
    }

    function utf8ize($mixed) {
        if (is_array($mixed)) {
            foreach ($mixed as $key => $value) {
                $mixed[$key] = utf8ize($value);
            }
        } elseif (is_string($mixed)) {
            return mb_convert_encoding($mixed, "UTF-8", "UTF-8");
        }
        return $mixed;
    }
2017-06-16 12:12:17
http://php5.kiev.ua/manual/ru/function.json-last-error.html
here is a small updated version of utf8ize that has the following addition : 
* It uses iconv instead of utf8_encode for potentially better result.
* It adds the support of objects variable 
* It also update array key value (in a case I met I had to utf8ize the key as well as those were generated from a user input value)

Here is the code.

<?php
   
function utf8ize($d) {
        if (
is_array($d)) {
            foreach (
$d as $k => $v) {
                unset(
$d[$k]);
       
$d[utf8ize($k)] = utf8ize($v);
            }
        } else if (
is_object($d)) {
       
$objVars get_object_vars($d);
        foreach(
$objVars as $key => $value) {
       
$d->$key utf8ize($value);
        }       
    } else if (
is_string ($d)) {
            return 
iconv('UTF-8''UTF-8//IGNORE'utf8_encode($d));
        } 
        return 
$d;
    }
?>
2018-03-27 17:15:55
http://php5.kiev.ua/manual/ru/function.json-last-error.html
Protected and private properties are ignored,
when json_encoding a class instance.
The snippet

<?php
class Example
{
    private   
$privateprop   "private property";
    protected 
$protectedprop "protected property";
    public   
$publicprop    "public property";
}
echo 
json_encode(new Example);
?>

only returns 
{"publicprop":"public property"}
2024-10-20 02:01:23
http://php5.kiev.ua/manual/ru/function.json-last-error.html

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