How handling error of JSON decode by try and catch

Question

I am unable to handle JSON decode errors. Here is my code:

try {
    $jsonData = file_get_contents($filePath) . ']';
    $jsonObj  = json_decode($jsonData, true);
}
catch (Exception $e) {
    echo '{"result":"FALSE","message":"Caught exception: ' . $e->getMessage() . ' ~' . $filePath . '"}';
}

I am a new PHP programmer. Sorry, if something is wrong.

See here: http://stackoverflow.com/questions/12265830/can-json-encode-trigger-a-catch-block — Gaurav Dave, Jul 23 '15 at 05:51

score 35 · Accepted Answer · answered Jul 23 '15 at 05:47

35

Another way to handle json decode error:-

if ($jsonObj === null && json_last_error() !== JSON_ERROR_NONE) {
   echo "json data is incorrect";
}

answered Jul 23 '15 at 05:47

I had to remove `$jsonObj === null`. – Jurakin Jun 15 '23 at 16:04

score 29 · Answer 2 · edited Oct 01 '21 at 15:48

29

Since PHP 7.3 one can use the JSON_THROW_ON_ERROR constant.

try {
    $jsonObj = json_decode($jsonData, $associative=true, $depth=512, JSON_THROW_ON_ERROR);
} catch (Exception $e) {
    // handle exception
}

More: https://www.php.net/manual/de/function.json-decode.php#refsect1-function.json-decode-changelog

edited Oct 01 '21 at 15:48

Valerio Bozz

1,176
16
32

answered Mar 18 '20 at 16:53

sergej

1,077
1
14
20

score 10 · Answer 3 · edited Jul 24 '17 at 19:51

10

May be you can try, validating json_decode

try {
  $jsonData = file_get_contents($filePath) . ']';
  $jsonObj  = json_decode($jsonData, true);

  if (is_null($jsonObj)) {
    throw ('Error');
  }
} catch (Exception $e) {
  echo '{"result":"FALSE","message":"Caught exception: ' . 
    $e->getMessage() . ' ~' . $filePath . '"}';
}

Read this too

edited Jul 24 '17 at 19:51

b00t

409
3
10

answered Jul 23 '15 at 05:47

Dimag Kharab

4,439
1
24
45

5

Why call `is_null()` when you can just check if `$jsonObj === null`? – reformed Aug 18 '17 at 13:52
There is no difference between comparing is_null() and === null. I would say its just a preference. Check this one https://stackoverflow.com/questions/8228837/is-nullx-vs-x-null-in-php for more information. – Milen Gardev Apr 28 '20 at 17:13
@MilenGardev the answer you linked to does not state "there is no difference". It in fact lists the differences, and thus which one to chose depends on the scenario. If you do not need a callback then there's no sense in not using the more performant `=== null` than the function which has additional overhead. – James Oct 22 '21 at 15:11
@James I would challenge you to benchmark the 2 cases side by side over 1000 iterations. The performance difference is so negligible that it almost won't even be measurable with microtime. Even in an environment that needs to be highly optimized, this wouldn't even make my list. – Lulceltech Jun 29 '22 at 17:51
"If you do not need XYZ then there's no sense in not using the more performant" – James Jun 30 '22 at 14:38

score 4 · Answer 4 · answered Jul 23 '15 at 05:46

json_decode returns null when a error occurs, like no valid json or exceeded depth size. So basically you just check with if whether the jsondata you obtained is null or not. If it is, use json_last_error to see what went wrong, if not then continue with the script.

$json_data = json_decode($source, true);

if($json_data == null){
  echo json_last_error() . "<br>";
  echo $source; // good to check what the source was, to see where it went wrong
}else{
  //continue with script
}

Something like that should work.

nope, when i exec json_decode on bad content, other code is useless, php return "Exception" and nothing i can do ! — Vladimir Ch, Aug 26 '22 at 12:39

How handling error of JSON decode by try and catch

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