from sqlalchemy.sql import desc, func from models import Location, Order, OrderItem, Product, User class FatModel: @classmethod def all(cls): return cls.query.all() @classmethod def amount(cls): return cls.query.count() class FatLocation(Location, FatModel): pass class FatOrder(Order, FatModel): # It's hard to add the unique user constraint, # as DISTINCT seems to apply after a GROUP BY and aggregate # So DISTINCT ... count(user_id) ... will count all users, # even if they get reduced by the disctinct afterwards. @classmethod def items_per_order(cls): return ( Order.query.join(OrderItem) .group_by(Order.id) .with_entities(Order.id, func.count(OrderItem.user_id).label("total")) ) class FatUser(User, FatModel): pass class FatOrderItem(OrderItem, FatModel): pass class FatProduct(Product, FatModel): @classmethod def top4(cls): top4 = ( OrderItem.query.join(Product) .join(Location) .group_by(Product.id) .with_entities( Product.name, Location.name, func.count(Product.id).label("count") ) .order_by(desc("count")) .limit(4) ) for top in top4: print(top)