form $_POST error, dynamic fields - php

Question

I have an error that I can't figure out...
Om my webpage there is a form that the user has the ability to add some new input fields to. If the user is submitting the form, then the optional fields is empty when the php-file is handing them, why?
HTML:
<form method="post" action="newRequest.php">
<input type="text" name="title" />
<input type="hidden" name="fname" value="0" />
<input type="checkbox" name="fname" value="1"/>
<input type="hidden" name="ename" value="0" />
<input type="checkbox" name="ename" value="1" />
<input type="hidden" name="seat" value="0" />
<input type="checkbox" name="seat" value="1" />
<input type="hidden" name="fields" value="0" />
<input type="text" id="fields" name="fields" />
<input type="submit" />
</form>
PHP:
if (strlen($_POST[title]) > 2) {
$toDb[title] = $_POST[title];
} else {
error('title');
}
$toDb[fname] = $_POST[fname];
$toDb[ename] = $_POST[ename];
$toDb[seat] = $_POST[seat];
if ($_POST[fields] > 0) {
$i = 0;
while ($i < $_POST[fields]) {
$toDb[optional][$i] = $_POST[optional-$i];
$i++;
}
$toDb[optional] = serialize($toDb[optional]);
} else {
$toDb[optional] = 0;
}
newEvent($toDb,$dbh);
JQuery that is adding dynamical fields:
$(document).ready(function() {
$('#fields').focusout(function(){
var fields = $('#fields').val();
var i = 0;
while(i < fields) {
$('#fields').after("Valfritt fält "+(i+1)+":<input type='text' name='optional"+i+"' />");
i++;
}
})
})

Answer 1

You should quote array indexes. It should be
$toDb['optional'][$i] = $_POST['optional'.$i];

Answer 2

You are missing commas in $_POST
$toDb['fname'] = $_POST['fname'];
$toDb['ename'] = $_POST['ename'];
$toDb['seat'] = $_POST['seat'];
Here is your modified code
if (strlen($_POST['title']) > 2) {
$toDb['title'] = $_POST['title'];
} else {
error('title');
}
$toDb['fname'] = $_POST['fname'];
$toDb['ename'] = $_POST['ename'];
$toDb['seat'] = $_POST['seat'];
if (count($_POST) > 0) {
$i = 0;
while ($i < count($_POST)) {
$toDb['optional'][$i] = $_POST['optional-'.$i];
$i++;
}
$toDb['optional'] = serialize($toDb['optional']);
} else {
$toDb['optional'] = 0;
}
newEvent($toDb,$dbh);
Also use count() to check if $_POST has values > 0.

Answer 3

I faced the same problem and I solved it using Javascript, like this :
add a new text field every time a button is pressed