PHP echo重定向

Question

I want to echo something in a post after submitting a form, then redirecting the header to cancel the double submit problem. Currently, Output_buffering turned on to allow the redirect to work. here some example code that illustrates the problem. Just make sure Output_buffering is on in php.ini.

<?php
   if(isset($_POST['submit'])){
   echo "hi";
}

   if (count($_POST) {
    header("Location: ".$_SERVER['REQUEST_URI']);
    exit();
    }
?>

<form action="<?php echo htmlentities($_SERVER['REQUEST_URI']); ?>" method="POST" name="edit" >
    <button type="submit" value="submit" name="submit">edit</button>
</form>

Answer 1

You should reverse the order.

On submit:

1. Process yours submit form.
2. Push desired output message into yours session.
3. Redirect to whatever/message page.

On message page show:

1. Retrive message, pushed to session.
2. Cleanup session record.
3. Display message.

It's can be separate page, same page, as with submit for, or any other page.

Or... Do the work with JavaScript and AJAX:

<?php
    if(isset($_POST['submit'])) {
        ...
        if (/all is ok/)
            die(json_encode(array('status' => 'ok', 'message' => 'Hi!')));
        else {
            die(json_encode(array('status' => 'err', 'message' => 'I\'m failed!')));
        }
    }
?>

<form action="<?php echo htmlentities($_SERVER['REQUEST_URI']); ?>" method="POST" name="edit" >
    <button type="submit" value="submit" name="submit">edit</button>
</form>
<script language="javascript">
  $('form').submit(function() {
      var parameters = ...; // collect parameters from form
      $.getJSON('/url-to-script', parameters)
       .success(function(response) {
           if (response.message == "ok")
               alert(response.message);
           else
               alert('Can\'t process input:
' + response.message);
       })
       .error(function(response) {
           alert('What a terrible failure!');
       });
  });
</script>

When .success() fired - you can show supplied message to user via alert/custom modal message box an then make redirect (document.location = '<?php echo ... ?>') or replace form on page with some custom message and link/button to proceed... Lots of variants.