在事务中间重定向是正常的事情吗？

Question

Here is a transaction structure:

try {
    $dbh_con->beginTransaction();

    // queries here

    $dbh_con->commit();

} catch(PDOException $e) {

    $dbh_con->rollBack();

}

Now I want to know can I use header('Location: ../); in the transaction? So what happens?

Here is 3 cases:

try {
    $dbh_con->beginTransaction();

    header('Location: ../mypage.php1'); // (1)

    // queries here

    $dbh_con->commit();

    header('Location: ../mypage.php2'); // (2)

} catch(PDOException $e) {

    header('Location: ../mypage.php3'); // (3)

    $dbh_con->rollBack();

}

Ok using a redirect code in where of (1), (2) and (3) is standard? And what happens with the queries in that case?

Based on the tests, when I redirect a script before commit() (even after queries), none of those queries never work. I mean nothing changes.

Answer 1

Redirection doesn't occur as soon as you use header(). The script continues to execute as normal. The header() will only take effect when the first piece of content is sent to the browser.

If you've set the same header multiple times, only the latest will be sent to the browser (the earlier setting is overwritten).

header('Location: /a.php');
... do some work
header('Location: /b.php');
...
//one of the lines below will cause redirection to /b.php
echo "first piece of content!"; //<- send to the browser if buffering is off
ob_flush();// <- send contents to browser if buffering is on

Of course in your example, if there is an exception, the catch block header will take effect since it will be the last set Location header.

Setting the same header multiple times in your script makes it harder to debug. Set it in one place, once you have enough info to know where to send the user:

try {
    $dbh_con->beginTransaction();
    // queries here
    $dbh_con->commit();
    $uri = '/a.php';

} catch(PDOException $e) {
    $uri = '/b.php';
    $dbh_con->rollBack();

} finally {
    header("Location: $uri");
}