Inventory tracking and combos

[aravindet]

Say there is a 2-day ticket, a day 1 ticket and a day 2 ticket. When either day 1 or day 2 tickets are fully sold out, the 2-day ticket should also be marked as fully sold out.

Bonus feature: When the day 1 tickets are 90% sold out, stop selling them but continue to offer the 2-day ticket (as that is more profitable).

Suggested implementation:

class SaleItem(...): # What’s currently called Item, except remove quantity
class InventoryItem(...): # Just quantity, number_sold? (if denormalizing)
class InventoryItemMap(): # Mapping
    quantity # over-rides the inventory item quantity, for satisfying bonus feature above
    multiplier # usually one, but if say a combo contains two t-shirts this will be 2

If not denormalizing, the query for retrieving availability information along with display items is very complex.

Edit: replaced DisplayItem with SaleItem

[shreyas-satish]

This is definitely a problem, and a good solution. Another solution to address the problem of tracking inventory, is to change the relationship between Item and ItemCollection to a many-to-many, where the join model can be named as ListedItem. If an item needs to be marketed differently based on the item collection it is being listed in, the ListedItem object can contain these specific details.

My sense is, this solution will require fewer changes to make to the code base.

[jace]

Related to #96, which can potentially remove the need for Item being present in more than oneItemCollection. Also, this will fix #75 which calls for renaming Item to something less generic.

[jace]

Deprecated by #171, which discusses the same idea and includes notes on complexities.