PonyORM problem

create.py

from models import *

c1 = Customer(email="1@1.com")
c2 = Customer(email="2@1.com")
o1 = Order(customer=c1)
o10 = Order(customer=c1)
o12 = Order(customer=c1)
o11 = Order(customer=c1)
o13 = Order(customer=c1)
o2 = Order(customer=c1)
o20 = Order(customer=c2)
o21 = Order(customer=c2)
o22 = Order(customer=c2)
o23 = Order(customer=c2)
o24 = Order(customer=c2)
p0 = Product()
p1 = Product()
p2 = Product()
p3 = Product()
p4 = Product()
p5 = Product()
p6 = Product()
p7 = Product()
p8 = Product()
p9 = Product()
i0 = OrderItem(product=p0, order=o11)
i1 = OrderItem(product=p1, order=o1)
i2 = OrderItem(product=p1, order=o10)
i3 = OrderItem(product=p6, order=o12)
i4 = OrderItem(product=p0, order=o13)
i5 = OrderItem(product=p2, order=o2)
i6 = OrderItem(product=p3, order=o20)
i7 = OrderItem(product=p1, order=o21)
i8 = OrderItem(product=p2, order=o22)
i9 = OrderItem(product=p2, order=o23)
b0 = Bonus(order_item=i0)
b1 = Bonus(order_item=i1)
b2 = Bonus(order_item=i2)
b3 = Bonus(order_item=i3)
b4 = Bonus(order_item=i4)
b5 = Bonus(order_item=i5, is_used=True)
b6 = Bonus(order_item=i6, is_used=True)
b7 = Bonus(order_item=i7)
b8 = Bonus(order_item=i8)
b9 = Bonus(order_item=i9)

models.py

from datetime import datetime
from decimal import Decimal
from pony.orm import *  # noqa

db = Database()


class Customer(db.Entity):
    id = PrimaryKey(int, auto=True)
    email = Required(str, unique=True)
    orders = Set('Order')


class Order(db.Entity):
    id = PrimaryKey(int, auto=True)
    customer = Required(Customer)
    order_items = Set('OrderItem')


class OrderItem(db.Entity):
    id = PrimaryKey(int, auto=True)
    order = Required(Order)
    product = Required('Product')
    bonuses = Set('Bonus')


class Product(db.Entity):
    id = PrimaryKey(int, auto=True)
    order_items = Set(OrderItem)


class Bonus(db.Entity):
    id = PrimaryKey(int, auto=True)
    order_item = Required(OrderItem)
    is_used = Required(bool, default=False)


db.bind(provider="postgres", user="postgres", password="postgres",
        host="localhost", database="pony", port="3306")  # the port param is not documented!

db.generate_mapping(create_tables=True)

query.py

c = Customer.select().random(1)[0]  # example
query = left_join(
        (
            p,
            count(i.order.customer == c),
            count((b.is_used == True) for b in i.bonuses),
            count(i)
        ) for p in Product
        for i in p.order_items)