Automatically Calculate Total

@gc40Jul 15.2007

Greetings All,
I have made a script that has 4 fields.

Quantity, Item Description, Item Unit Price and Total.

The first field, quantity is a form field which a user enters the amount into. The description and unit price fields are data pulled from a database.

The total field is a field which automatically calculates the Quantity Field multiply by the Unit Price.
My problem is getting the “total” field to automatically generate a value once a customer enters a numeric value into the quantity field.

Can anyone point me in the right direciton?
I figure the solution would be one of dhtml or ajax since the total field would update on the fly once quantity changes.
Any help would be appreciated.

to post a comment

PHP

3 Comments(s) _↴

@manyamileJul 15.2007 — #Ok while I am waiting for my own answer I'll answer yours. I am not an expert and while I have no doubt as to the way I'd do it the way I explain it may not be the best.

1. I would use ajax (like you said) to bring the description and unit price to javascript. The only thing I would do in php would be the mysql queries (unless you want to build a table with a variable number of rows, when using php is easier, otherwise you need the dom).

2. In html you have your <form>...</form> tags that have your input fields in between. I would also put a submit button in there, (otherwise how would the program know when the user is done writing?)

<input type="submit" value="Submit" onclick="calculate()"/><br />

Now calculate() is a function that will be called when you click submit.

If the field quantity is of the form:<input type="text" id="quantity" />

then you can access its contents in javascript with: qty=document.getElementById("quantity").style.value

which must be placed inside the calculate function - that is using dhtml.

But you are in the php forum. If you want everything in php you can't use dhtml or ajax ( it has javascript objects and you use it if you want to send information without reloading the page.)

Maybe this mixture of javasdript in a php forum is why people are not answering. I wish I knew why they aren't answering mine.

To do it with php alone:

You need an html file:

<html><body>

<form action="process.php" method="post">

Quantity: <input name="quantity" type="text" />

<input type="submit" />

</form>

</body></html>

Call this second file "process.php"

<html><body>

<?php

$quantity = $_POST['quantity'];

$price=$quantity* $unit;

echo "Total price is ". $price ;

?>

</body></html>

You can read more at: tizag.com

Actually I don't know if you can write to an input field using php alone.

Good luck on your project!

@gc40authorJul 15.2007 — #I found a script that does what something similiar with the calculations that I want, however, their are two include files that are encrypted.

Here is the script:

[code=php]<?php
 
 include('logic/edit_invoice.php');
 include('include/editinvjs.php');
 
 ?>
 <form method="post" name="fmaddinvoice" id="fmaddinvoice" action="<?php echo $_SERVER['PHP_SELF']; ?>" onsubmit="return finalCheck();">
 <br>
 <table border="0" align="center">
 <tr><td><b><?php echo INV_DATE; ?></b></td><td><input type="text" size="10" name="invdate" value="<?php echo date('Y-m-d'); ?>"> </td></tr>
 <tr><td><b><?php echo ORDER_ID; ?></b></td><td><input type="text" size="20" name="order_id" maxlength="32" value="<?php echo $order_id; ?>"></td></tr>
 
 
  <tr><td>
   <b><?php echo DETAILS; ?></b>
  </td><td>
   <!--textarea name="details" cols="50" rows="12"></textarea-->
 
   <table align="center" border="0">
   <tr><td align="center"><b>No.</b></td><td align="center"><b><?php echo DESC; ?></b></td><td align="center"><b><?php echo QTY; ?></b></td><td align="center"><b><?php echo $moneyunit; ?>/<?php echo UNIT; ?></b></td><td align="center"><b><?php echo TAX; ?></b></td><td align="center"><b><?php echo TOTAL; ?></b></td></tr>
   <?php for($i=0; $i< $rowed1; $i++){ ?>
   <tr>
   <td><input type=text size=2 name="r<?php echo $i; ?>" value="<?php echo ($i+1); ?>" maxlength="5">:</td>
   <td><input type=text size=20 name="d<?php echo $i; ?>" value="<?php echo $prod_list[$i]['product_name']; ?>"></td>
   <td><input type=text size=2 name="n<?php echo $i; ?>" value="<?php echo $prod_list[$i]['qty']; ?>"  onchange="checkNumber(this);subSum(<?php echo $i; ?>);"></td>
   <td><input type=text size=6 name="p<?php echo $i; ?>" value="<?php echo $prod_list[$i]['price']; ?>"  onchange="checkNumber(this);subSum(<?php echo $i; ?>);"></td>
   <?php
   if(isset($prod_list[$i]['tax'])){
   $temtax = $prod_list[$i]['tax'];
   }else{
   $temtax = $taxrate;
   }
   ?>
   <td><input type=text size=5 name="ta<?php echo $i; ?>" value="<?php echo $temtax; ?>" onchange="checkNumber(this);remind(this.value);subSum(<?php echo $i; ?>);"></td>
   <?php
   if(isset($prod_list)){
   $total_value = $prod_list[$i]['qty']*$prod_list[$i]['price']*(1+$temtax);
   $total_value = num_filter($total_value);
   }
   ?>
   <td><input type=text size=7 name="to<?php echo $i; ?>" value="<?php echo $total_value; ?>"  onchange="checkNumber(this);subSum(<?php echo $i; ?>);redoTotal();"></td>
   </tr>
 
   <?php } ?>
   </table>
   <div id="item2" style="display:none">
   <table align="center">
   <?php for($i=$rowed1; $i<$rowed2; $i++){ ?>
   <tr>
   <td><input type=text size=2 name="r<?php echo $i; ?>" value="<?php echo ($i+1); ?>" maxlength="5">: </td>
   <td><input type=text size=20 name="d<?php echo $i; ?>"></td>
   <td><input type=text size=2 name="n<?php echo $i; ?>" onchange="checkNumber(this);subSum(<?php echo $i; ?>);"></td>
   <td><input type=text size=6 name="p<?php echo $i; ?>" onchange="checkNumber(this);subSum(<?php echo $i; ?>);"></td>
   <td><input type=text size=5 name="ta<?php echo $i; ?>" value="<?php echo $taxrate; ?>" onchange="checkNumber(this);remind(this.value);subSum(<?php echo $i; ?>);"></td>
   <td><input type=text size=7 name="to<?php echo $i; ?>" onchange="checkNumber(this);subSum(<?php echo $i; ?>);redoTotal();">
   </td>
   </tr>
 
   <?php } ?>
   </table>
   </div>
 </td></tr>
 <tr><td>
 <b><?php echo NET_TOTAL; ?></b>
 </td><td><?php echo $moneyunit; ?>
 <input type="text" name="totbt" size="8" value="0">
 </td></tr>
 <tr><td>
 <b><?php echo TAX; ?>:</b>
 </td><td><?php echo $moneyunit; ?>
 <input type="text" name="tottax" size="7" value="0">
 </td></tr>
 <tr><td>
 <b><?php echo GREAT_TOTAL; ?></b>
 </td><td><?php echo $moneyunit; ?>
 <input type="Text" name="total" size="8" value="0">
 </td></tr>
 <tr><td colspan=2 align="center">
 <input type="submit" name="submit" value="<?php echo ADD_INV; ?>"><br><br>
 </form>
 </td></tr>
 
  </table>
   <script language="javascript">
   redoTotal();
   </script>
 <?php
 ?>
 [/code]

@gc40authorJul 16.2007 — #Help please?

Also in #PHP _↴

Cant figure out. Possible bug?numbers Validate input: Blog stripslashes?

Success!

Help @gc40 spread the word by sharing this article on Twitter...

Tweet This

Automatically Calculate Total

3 Comments(s) _↴

Also in #PHP _↴

Success!

Social

Version

Automatically Calculate Total

3 Comments(s) ↴

Also in #PHP ↴

Success!

The web is an endless sea of information. Don't miss the boat... Subscribe!

Social

Version

3 Comments(s) _↴

Also in #PHP _↴