Need help with fn_get_products filters

I'm trying to filter products by categories where by products returned are only in cat A AND cat B. I can get all products in both categories by using $params['cid'] = array('123','321'); but this returns all products in cat a and cat b. I need it to return only those that are in both.

for example: 3 products.

prod1 in cat A

prod2 in cat B

prod3 in cat A and cat B

how do I get only prod3 from fn_get_products?


using v4 cs cart

You will have to use the 'get_product_data' hook and add

an appropriate inner join so that product_id must be in both cat1 and cat2.