session 中的复选框表单无法正常工作

Question

I'm trying to write the code for an online form:

On page 1 there are just some demographic questions. It's on that first page I start a session. When they submit their answers they get redirected to page 2 where I place some statements on which they can select their level of agreement. - In case they want to go back their answers on the previous page are remembered thanks to the session. - Ultimatly their answers will be transferred to a database (haven't written that yet).

Problem: 1) I tried to multiply the amount of questions to 3 questions on page 2 but when I go to page 3 and return to page 2 the answers aren't remembered?

2) If I only check some of the questions (not all of them) I get 'Notice: Undefined index:' with the line the unanswered question is on. Can this be solved somehow?

This is the code from page 2:

<form action="page3.php" method="post">
<?php
    $options = array(
        'Good' => 'Good',
        'Neutral' => 'Neutral',
        'Bad' => 'Bad',
);

checkbox( 'Question_1', 'Question_1', 'How good is your health?', $options );
checkbox( 'Question_2', 'Question_2', 'How good is your math?', $options );
checkbox( 'Question_3', 'Question_3', 'How good is your knowledge of astrofysics?', $options );

?>

<?php submit('Go To Step 3 &raquo;'); ?>
</form>

This is the code from page 3 (where the info from page 2 is stored in the SESSION variables):

<?php
include_once('header.php');

// Store data from page 1 in session
if ( ! empty( $_POST ) ) {
  $_SESSION['Question_1'] = $_POST['Question_1'];
  $_SESSION['Question_2'] = $_POST['Question_2'];
  $_SESSION['Question_3'] = $_POST['Question_3'];
}

?>

And this is the code of the used function (from functions.php):

function checkbox( $name, $id, $label, $options = array() ) {?>
  <div class="form-group">
    <p><?php echo $label; ?></p>
    <?php foreach ( $options as $value => $title ) : ?>
      <label class="checkbox-inline" for="<?php echo $id; ?>">
        <input type="checkbox" required name="<?php echo $name; ?>[]" value="<?php echo $value; ?>" <?php isset($_SESSION['Question_1'],$_SESSION['Question_2'],$_SESSION['Question_3']) ? checked="checked":; ?>>
        <span class="checkbox-title"><?php echo $title; ?></span>
      </label>
    <?php endforeach; ?>
  </div>

What am I doing wrong?

Answer 1

The issue is with this line:

    <input type="checkbox" required name="<?php echo $name; ?>[]" value="<?php echo $value; ?>" <?php isset($_SESSION['Question_1'],$_SESSION['Question_2'],$_SESSION['Question_3']) ? checked="checked":; ?>>

It should probably be something like:

    <input type="checkbox" required name="<?php echo $name; ?>[]" value="<?php echo $value; ?>" <?php isset($_SESSION[$id]) ? checked="checked":; ?>>