Assign ID to options in a drop down box and pass as IPN variable

I have a rather complicated issue that I am trying to solve in PHP and Paypal's IPN codes..

I am selling one product wh开发者_开发技巧ich has multiple licenses in a drop down box, for example:

5 users - $20 10 users- $50 20 users - $100

Once someone purchases a license, I got the $payment_amount passed from paypal and did an if, ifelse statement to generate the number of usernames accordingly.

I did not think about different currencies, therefore this technique won't work. Instead, I need to be able to assign an ID to each option in the drop down box and pass that instead.

I was wondering if this is possible and how I might go about doing this.

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You could easily use any of the variables in the list of HTML variables to accomplish what you wish.

1. You could use invoice, and save the information to a database.
2. You could use on0 and os0 to define your own variables and price values.
3. You could define the 'custom' variable and set it to whatever your dreams desire.

All of them are equally effective, though the most commonly used method is probably #2.

<form target="paypal" action="https://www.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_cart">
<input type="hidden" name="business" value="tester@test.com">
<input type="hidden" name="lc" value="US">
<input type="hidden" name="item_name" value="asdfsafd">
<input type="hidden" name="button_subtype" value="products">
<input type="hidden" name="no_note" value="0">
<input type="hidden" name="add" value="1">
<input type="hidden" name="bn" value="PP-ShopCartBF:btn_cart_LG.gif:NonHostedGuest">
<table>
<tr><td><input type="hidden" name="on0" value="numUsers">numUsers</td></tr><tr><td><select name="os0">
    <option value="5 users">5 users $5.00</option>
    <option value="10 users">10 users $9.00</option>
    <option value="20 users">20 users $17.00</option>
</select> </td></tr>
</table>
<input type="hidden" name="currency_code" value="USD">
<input type="hidden" name="option_select0" value="5 users">
<input type="hidden" name="option_amount0" value="5.00">
<input type="hidden" name="option_select1" value="10 users">
<input type="hidden" name="option_amount1" value="9.00">
<input type="hidden" name="option_select2" value="20 users">
<input type="hidden" name="option_amount2" value="17.00">
<input type="hidden" name="option_index" value="0">
<input type="image" src="https://www.paypalobjects.com/en_US/i/btn/btn_cart_LG.gif" border="0" name="submit" alt="PayPal - The safer, easier way to pay online!">
<img alt="" border="0" src="https://www.paypalobjects.com/en_US/i/scr/pixel.gif" width="1" height="1">
</form>