cannot redirect after mysqli connection error

Question

I am new to php. I am trying to redirect to a error page in php when I get a mysql connection error, but I get an error stating that I cannot modify the header because the output was already sent on line 8 (where I created the connection). Please can you advise on the proper way of doing this?

<?php
$servername = "localhost:3306";
$username = "danny";
$password = "sql1";
$dbname = "testdb";

  try{
      $conn = new mysqli($servername, $username, $password, $dbname);
  }
  catch(Exception $e){
  header('Location: /connection_error.php');
  die();
}


?>

Thanks

Danny

score 3 · Accepted Answer · answered May 01 '17 at 16:45

3

You need to add this line at the top to tell mysqli to throw exceptions

mysqli_report(MYSQLI_REPORT_STRICT); 
$servername = "localhost:3306";
$username = "danny";
$password = "sql1";
$dbname = "testdb";

  try{
      $conn = new mysqli($servername, $username, $password, $dbname);
  }
  catch(Exception $e){
  header('Location: /connection_error.php');
  die();
}

answered May 01 '17 at 16:45

Agam Banga

2,708
1
11
18

thank you this worked. Can I close the connection in the catch block – DannyR May 01 '17 at 16:53
@DannyR The connection is not opened; that is why it got into Exception – Agam Banga May 01 '17 at 16:55

score 0 · Answer 2 · answered May 01 '17 at 17:01

Additionally, you can always check the error code from the last connect call by using mysqli::$connect_errno, whereas it returns an error code value for the last call, if it failed. Zero means no error occurred (hence the falsey).

<?php
    /* Variable Defaults */
    $servername = 'localhost:3306';
    $username   = 'danny';
    $password   = 'sql1';
    $dbname     = 'testdb';

    /* Make Connection */
    $conn = new mysqli($servername, $username, $password, $dbname);

    /* Check Connection */
    if($conn->connect_errno) {
        /* Redirect */
        header('Location: /connection_error.php');
        exit();
    }
?>

If your `mysqli` call is displaying a notice, you will not be able to use `header()` since the headers have already been sent. I would suggest modifying your `error_reporting` to not display notices. — Daerik, May 01 '17 at 17:04

score -1 · Answer 3 · answered May 01 '17 at 16:43

-1

Try this

<?php
ob_start();

$servername = "localhost:3306";
$username = "danny";
$password = "sql1";
$dbname = "testdb";

  try{
      $conn = new mysqli($servername, $username, $password, $dbname);
  }
  catch(Exception $e){
  header('Location: /connection_error.php');
}

ob_flush();
?>

answered May 01 '17 at 16:43

Mhd.Jarkas

406
2
5
11

Flushing the buffer makes no difference in this case. – Jesse Schokker May 01 '17 at 16:49
It's not going at all to catch the error, because the connection will be stopped and give warning that access denied. – Mhd.Jarkas May 01 '17 at 17:08

cannot redirect after mysqli connection error

3 Answers3