“.where”查询后的活动记录关联

I've got three models: Decks, Slots and Cards. I put them together like so... Decks are made of many slots, each slot contains one card and any one card can show up in a number of different slots. I modeled it after the "Order - Order Line Item - Product" structure, hope that makes sense.I've got three models: Decks, Slots and Cards.