Prepare form with multiple product options for Paypal - php

Question

How can I prepare the option selection in the form to be sent to paypal?
I have tried,
<form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="item_name_1" value="Book 1" />
<input type="hidden" name="item_number_1" value="1">
<input type="hidden" name="amount_1" value="0.10" />
<input type="hidden" name="quantity_1" value="1"/>
<input type="hidden" name="option_name1" value="sizes">
<input type="hidden" name="option_select1" value="Large"/>
...
or
<form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="item_name_1" value="Book 1" />
<input type="hidden" name="item_number_1" value="1">
<input type="hidden" name="amount_1" value="0.10" />
<input type="hidden" name="quantity_1" value="1"/>
<input type="hidden" name="on0" value="sizes">
<input type="hidden" name="os0" value="Large"/>
But I can't get any option data returned from $_POST
Besides, what if I have multiple products with different options, then how do I prepare the form?
For instance, product 1 has the size small as the selection, while product 2 has the size large as the selection. I assume that it could be like this?
....
<input type="hidden" name="option_name1" value="sizes">
<input type="hidden" name="option_select1" value="Large"/>
....
<input type="hidden" name="option_name1" value="sizes">
<input type="hidden" name="option_select2" value="Small"/>

Answer 1

You have to give an unique name for each product,
if you want to get back the post value in PHP
suc as :-
<input type="hidden" name="option_name[$id1]" value="sizes">
<input type="hidden" name="option_select[$id1]" value="Large"/>
...
<input type="hidden" name="option_name[$id2]" value="sizes">
<input type="hidden" name="option_select[$id2]" value="Large"/>
You can also use option_name[],
but this only return an indexed array in the $_POST
Also, why are you using hidden for option?
This is my understanding of option :-
<select name="sizes[$id1]">
<option value="Large">Large</option>
<option value="Large">Small</option>
</select>
...
<select name="sizes[$id2]">
<option value="Large">Large</option>
<option value="Large">Small</option>
</select>