Send forms to separate pages for handling, or back to the same page?

Question

Is it better to send an html form to a seperate page, or send it back to the same page??

i keep hearing to seperate logic from presentation, so I was wondering if I should seperate my forms from my form handlers as well.

As of now, Im doing this...

<?php

if(isset($_POST['submitted'])){

  //Validate the form
  if(empty($_POST['name'])){
    $errors['name'] = 'Please enter your name';
  }

  //IF no errors INSERT INTO database and redirect
}
?>

<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
  <input type="text" name="name" value="<?php if(isset($_POST['name'])) echo $_POST['name']; ?>" />
  <?php if(isset($errors['name'])) echo '<span class="error">'.$errors['name'].'</span>'; ?>
  <input type="submit" />
</form>

Is this good, or should I completely seperate the php from the form and just include one into the other... or something of the sort

Answer 1

I actually find having the submission processing logic in a separate file that would be included (in my class a class) allows you to keep your logic away from the presentation, but have the errors of validation/etc appear directly on your form where you expect them to. A small example of what I propose:

<?php // form.php
  $form = array(
     "test"=>"default value",
  );
  $errors = array();

  if (count($_POST)) {
    include "form.process.php";
  }

  if (count($errors)) {
    echo "<ul class='errors'>";
    foreach ($errors as $error) {
      echo "<li>".htmlentities($error)."</li>";
    } 
    echo "</ul>";
  }
?>
<form method="POST"> <!-- no action means submit to the same page you are on -->
<input type='text' name='test' value='<?php echo $form["test"]; ?>'/>
<input type='submit'>
</form>

Then in form.process.php

 <?php
   if (isset($_POST['test')) {
     $test = $form['test'] = $_POST['test'];
     if (!trim($test)) // empty string? {
       $errors[] = "Please fill in test field";
     }
   }

   if (!count($errors)) {
     header("Location: formsubmitted.php");
     exit;
   }