Product combinations stock control options applied to main item

[globalgt]

Hi all

I have my website set up so that i have drop down options to add features to a product,

I am using the combinations feature to do this

 

My question is this,

how to set the main item stock as 10 and an add on item as 10 and have them decrease individually, but no matter what option the main item needs to decrease.

 

my example is this:

I have 10 computers, you can order one

on my computer page using combinations tab you can add a usb cable

if you buy this option i should have 9 computers and 9 cables

if you then buy the option of just a computer i should have 8 computers and 9 cables

 

as I currently have it i need to add 10 computers and 10 options of computers and usb cables

so if you buy a computer and a usb cable it shows 9

if someone then buys a computer it shows 9 of each

but i only have 8 computers now and 9 usb cables

and my stock shows 18 computers as it is adding the options together

 

I am just starting with prestashop so this may be a easy fix, I have googled and tried the forum but unless you know the exact terminology to search the results are not found!!

Thanks

James

Edited August 27, 2015 by globalgt (see edit history)

[gabdara]

By default PrestaShop doesn't work as you want in the example above.

You could create a custom module in which you associate different products with a corresponding attribute and make it that whenever the attribute is used the associated product will reduce its stock by the number of quantity ordered.

This will have to take into consideration scenarios like when the associated product is out of stock the combinations that use that attribute must be disabled.