PHP File upload script getting in the way - php

Question

I have this form
If the first radio button is clicked, the textfield below it is enabled and if the 2nd radio button is clicked, the file upload is enabled and the former is disabled,vice versa. It works fine if the file upload option is chosen but if the 1st radio button is chosen and the file upload is disabled, it doesn't insert data in the database. :/ What should be done to successfully send the form details even if the file upload is disabled/empty?
CODE:
<form name="form" method="POST" enctype="multipart/form-data">
<table width="416" height="245" border="1" align="center">
<tr>
<td colspan="2">Transaction No: <input type="text" name="transaction_no" id="transaction_no" /> </td>
</tr>
<tr>
<td colspan="2" align="center">Please select the mode of payment</td>
</tr>
<tr>
<td width="183" align="center"><input name="rad" type="radio" onclick="enableField(this)" value="Smart Money" checked="checked">
Smart Money</td>
<td width="201" align="center"><input name="rad" type="radio" onclick="enableField(this)" value="BPI"> BPI Bank Deposit</td>
</tr>
<tr>
<td align="center"><input type="text" name="contactno" id="contactno"></td>
<td align="center"><input name="filename" type="file" id="filename" disabled="disabled"/></td>
</tr>
<tr>
<td>Total amount sent:</td>
<td> <input type="text" name="totalsent" id="totalsent" /></td>
</tr>
<tr>
<td>Date sent:</td>
<td> <input type="text" name="datesent" id="datesent" /></td>
</tr>
<tr>
<td colspan="2" align="center"><input name="submit" type="submit" id="submit" value="Submit" /></td>
</tr>
</table>
<input type="hidden" name="MM_insert" value="form" />
</form>
PHP
<?php
if(isset($_FILES['filename'])){
$errors = array();
$file_name = $_FILES['filename']['name'];
$file_size =$_FILES['filename']['size'];
$file_tmp =$_FILES['filename']['tmp_name'];
$file_type=$_FILES['filename']['type'];
$file_ext=strtolower(end(explode('.',$_FILES['filename']['name'])));
$expensions= array("jpeg","jpg","png");
if(in_array($file_ext,$expensions)=== false){
$errors[]="extension not allowed, please choose a JPEG or PNG file.";
}
if($file_size > 2097152){
$errors[]='File size must be excately 2 MB';
}
// pag walang error...
if (empty($errors)==true) {
// upload the file...
move_uploaded_file($file_tmp,"uploads/".$file_name);
$servername = "localhost";
$username = "root";
$password = " ";
$dbname = "admin";
// create new record in the database
include ("dbinfo.php");
mysql_query("INSERT INTO payment_form (date, Tracking, mode, ContactNo, totalsent, datesent, filename) VALUES (NOW(), '$transactionNo', '$rad', '$contactNo', '$totalSent', '$dateSent', '$file_name')") ;
header('Location: paymentform_success.php');
}else{
print_r($errors);
}
}
?>
Javascript for enable/disable
<script type="text/javascript">
function enableField(obj){
var form=obj.form;
var txtNames=['contactno','filename'], f;
var rads=document.getElementsByName(obj.name), r, i=0;
while(r=rads[i++]){
f=form[txtNames[i-1]];
if(r.checked){
f.removeAttribute('disabled');
f.focus();
}
else{
f.value='';
f.setAttribute('disabled','disabled')
}
}
}
</script>

Answer 1

You should first check which radio is checked and then decide what to do. It's not working because the whole script is under the if(isset($_FILES['filename'])). If the file upload is disabled then $_FILES will not be set and nothing will be executed.