Dynamic Select Boxes work half - php

Question

I have two fail for my script.
1.publicAdvart.php
<script type="text/javascript">
$(document).ready(function () {
$('#select_marka').change(function () {
$.post(
'modeli.php',
{id: $('#select_marka').val()},
function (res) {
$('#model').html(res);
}
);
});
});
</script>
<select class="form-control" name="marka" id="select_marka">
<option></option>
<?php
$sel = "SELECT * FROM marka";
$query = mysqli_query($conn, $sel);
while ($row = mysqli_fetch_array($query)) {
?>
<option value="<?php echo $row['id']; ?>"><?php echo $row['marka']; ?></option>
<?php
}
?>
</select>
2.modeli.php
<?php
if (isset($_POST['id']) && $_POST['id'] != '') {
$marka_id = $_POST['id'];
?>
<select id="select_marka" class="form-control">
<?php
$selModel = "SELECT * FROM marka_model WHERE marka_id='$marka_id'";
$queryModel = mysqli_query($conn, $selModel);
while ($rows = mysqli_fetch_array($queryModel)) {
?>
<option value="<?php echo $rows['model']; ?>"><?php echo $rows['model']; ?></option>
<?php
}
?>
</select>
<?php
}
?>
Where is a problem? These two script half work.
This is OK click "Opel" -> "meriva". http://i.stack.imgur.com/ma5XZ.jpg
Next step 2 is a problem, i want "name" marka and "name" model.
Problem this is here.I don't get "marka - id", i want "name" http://i.stack.imgur.com/Nm1Yk.jpg
Update:
step2.php
<?php
if (isset($_POST['submit'])) {
$marka = $_POST['marka'];
$model = $_POST['model'];
$_SESSION['marka'] = $marka;
$_SESSION['model'] = $model;
}
?>
<div class="col-md-12 well advertTittle">
<h4 class="well">
<?php echo $_SESSION['marka'] . '&nbsp' . $_SESSION['model'] . '&nbsp' . stripslashes($_SESSION['modify']); ?>
</h4>
<span><?php echo $_SESSION['price'] . ' лв.'; ?></span>
</div>

Answer 1

You forget to give the "name" attribute for yours "marka" select field:
<?php
...
?>
<select id="select_marka" class="form-control"> // <- here
<?php
$selModel = "SELECT * FROM marka_model WHERE marka_id='$marka_id'";
....
Should be something like this:
<?php
...
?>
<select id="select_model" class="form-control" name="model"> // <- here!!!
// "id" attribute also should be changed
<?php
$selModel = "SELECT * FROM marka_model WHERE marka_id='$marka_id'";
....
Also, yours step2.php should be like this:
<?php
if (isset($_POST['submit'])) {
$_SESSION['marka'] = $_POST['marka'];
$_SESSION['model'] = $_POST['model'];
}
function validData($data) {
return
isset($data['marka'])
&& isset($data['model'])
&& isset($data['price'])
;
}
if (validData($_SESSION)) {
$marka_id = intval($_SESSION['marka']);
$model_id = intval($_SESSION['model']);
$marka = mysqli_fetch_array(mysqli_query($conn, "SELECT name FROM marka where id = $marka_id"));
$model = mysqli_fetch_array(mysqli_query($conn, "SELECT name FROM marka_model WHERE id = $model_id"));
?>
<div class="col-md-12 well advertTittle">
<h4 class="well">
<?php echo $marka['name'] . '&nbsp' . $model['name'] . '&nbsp' . (isset($_SESSION['modify']) ? stripslashes($_SESSION['modify']) : ''); ?>***
</h4>
<span>
<?php echo $_SESSION['price'] . ' лв.'; ?>
</span>
</div>
<?php } else { ?>
Not all fields filled.
<?php } ?>