White space at start of encoded json array

Question

Admittedly it has been a while since I have been in the php world, but i'm not sure why I am getting 3 spaces at the start of my json_encode string.

"   [{"id":"1","display_name":"Bob"}]"

This is the php i have:

$stmt = $conn->prepare("SELECT * FROM users");

$queryResult = array();
if ($stmt->execute()) {
  while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
      $queryResult[] = $row;
  }
  echo json_encode($queryResult);
}

When I echo print_r($stmt->fetch(PDO::FETCH_ASSOC)) I get the following:

   Array
(
    [id] => 1
    [display_name] => Twitch Dock John
)

The 3 spaces are there as well.. what have I done wrong (expecting an incoming face-palm moment)?

You've got something else somewhere outputting those spaces. — user3942918, Apr 03 '17 at 10:28
as you can tell already, neither PDO nor JSON has nothing to do with your issue. even if you make it `echo 'Hello world';` the spaces would be there — Your Common Sense, Apr 03 '17 at 10:30
Just try to echo something before your if() , And `echo json_encode($queryResult);` It will help you to check from where this space is coming. — Dipanwita Kundu, Apr 03 '17 at 10:33
Work around / patch can be to use http://php.net/manual/en/function.trim.php to strip white spaces from the string. — Louis Loudog Trottier, Apr 03 '17 at 10:37
Update: Thanks for all of the comments guys, it is re-assuring that the consensus is that the PDO is ok. I'm currently looking for additional output (fun) - I'll update if necessary. — Zze, Apr 03 '17 at 11:22

score 5 · Answer 1 · answered Apr 03 '17 at 10:36

5

You can possibly figure the spot in your codebase where output starts by determining where HTTP headers have been sent:

if (headers_sent($file, $line)) {
    echo "Ouput starts on: $file: $line\n";
}

answered Apr 03 '17 at 10:36

Álvaro González

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AS this is probably not an answer to the question it is a very usefull thing to know. – Louis Loudog Trottier Apr 03 '17 at 10:39
@LouisLoudogTrottier Why not an answer? Since the sole purpose of the script is to emit JSON, any prior output is probably an error. – Álvaro González Apr 03 '17 at 10:40
This answer way exceeded my expectations for this question. This is incredibly useful! – Zze Apr 03 '17 at 11:20
it does not fix the error but it will tell you where it is. But again, this is awesome. – Louis Loudog Trottier Apr 03 '17 at 18:29
@LouisLoudogTrottier Yep. Then comes the difficult part, opening the offending file and hitting **del** ;-P – Álvaro González Apr 04 '17 at 07:14
maybe consider adding it to the main thread => http://stackoverflow.com/questions/8028957/how-to-fix-headers-already-sent-error-in-php function `header_sent()`is nowhere to be found. – Louis Loudog Trottier Apr 04 '17 at 07:17
@LouisLoudogTrottier When you get *Headers already sent* the error message already includes the information that `headers_sent()` provides. – Álvaro González Apr 04 '17 at 07:34
Yes i know, but people without error_logging knowledge does not, here comes the hard part => open the log file ;-) – Louis Loudog Trottier Apr 04 '17 at 08:18

White space at start of encoded json array

1 Answers1