Data-Access-Object for working with Redis database

dao.py

from json import dumps, loads

class Price:
  def __init__(self, db):
    self.db = db
  def __getitem__(self, item):
    price = self.db.hget("price", item)
    if price:
      return int(price)

class Stock:
  def __init__(self, db):
    self.db = db
  def __iter__(self):
    return iter(self.db.hkeys("stock"))

  def __getitem__(self, item):
    units = self.db.hget("stock", item)
    if units:
      return int(units)
    return 0

  def __setitem__(self, item, units):
    self.db.hset("stock", item, units)
    
class Orders:
  def __init__(self, db):
    self.db = db
    self.len = 0

  def cancel(self, oid):
    self.db.hdel(f"order:{oid}", "items", "total", "owner", "state")

  def create(self, uid, order, total):
    oid = self.len + 1
    self.db.hset(f"order:{oid}", "items", dumps(order))
    self.db.hset(f"order:{oid}", "total", total)
    self.db.hset(f"order:{oid}", "owner", uid)
    self.db.hset(f"order:{oid}", "state", "unpaid")
    self.len += 1
    return oid

  def all(self):
    result = []
    for order in self.db.keys("order:*"):
      result.append(int(order[len("order:"):]))
    return result

  def for_user(self, uid):
    result = []
    for order in self.db.keys("order:*"):
      owner = self.db.hget(order, "owner")
      if str(uid) == owner:
        result.append(int(order[len("order:"):]))
    return result

  def set_state(self, oid, state):
    self.db.hset(f"order:{oid}", "state", state)

  def __getitem__(self, oid):
    items = self.db.hget(f"order:{oid}", "items")
    if items:
      order = loads(items)
      total = self.db.hget(f"order:{oid}", "total")
      owner = self.db.hget(f"order:{oid}", "owner")
      state = self.db.hget(f"order:{oid}", "state")
      return (order, int(total), int(owner), state)