Solution #873

Ivan-Shakhman · 2024-09-02T12:41:49Z

first try.. the game begining

MNDonut

The Squid Game Season 2 started 🔪

MNDonut · 2024-09-03T04:20:02Z

db/models.py

+
+class Order(models.Model):
+ created_at = models.DateTimeField(auto_now_add=True)
+ user = models.ForeignKey(to=User, on_delete=models.CASCADE)


use AUTH_USER_MODEL instead because when use change the model inside this constant, then it won't be updated here

MNDonut · 2024-09-03T04:20:33Z

db/models.py

+ related_name="ticket"
+ )
+ order = models.ForeignKey(
+ to=Order,
+ on_delete=models.CASCADE,
+ related_name="ticket"


are you sure it's an appropriate name? related manager returns 1 object for FK or queryset?

MNDonut · 2024-09-03T04:21:05Z

db/models.py

+ fields=["movie_session", "row", "seat"],
+ name="unique_ticket"


specify what fields are unique in index name so that other devs know it

MNDonut · 2024-09-03T04:25:25Z

services/movie_session.py

+ movie_session = MovieSession.objects.get(pk=movie_session_id)
+ result = []
+ for row in range(1, movie_session.cinema_hall.rows + 1):
+ for seat in range(1, movie_session.cinema_hall.seats_in_row + 1):
+ if Ticket.objects.filter(
+ movie_session=movie_session,
+ row=row,
+ seat=seat
+ ).exists():
+ result.append({"row": row, "seat": seat})


wow. An advice for you. Try to avoid such constructions that make 1 sql query on each iteration(when possible)
From performance perspective it's really bad idea because if your hall has 10 rows and 10 seats, it's 100 iterations meaning 100 queries in db and it's will take too much time to just fetch available seats.
The best way is to do everything using ORM that will fetch it in 1-2 sql queries. If you work with something bigger than cinema hall

(наприклад система продажу квартир у житловому комплексі, який має 6 корпусів, у кожному по 4 під'їзди, кожен комплекс має 15 поверхів і кожен поверх має 20 квартир, то в цьому випадку ти б зробив 4 цикли(кожен корпус, під'їзд, поверх і квартира) і це було б 6 * 4 * 15 * 20 = 7200 запитів до бази даних, щоб подивитися які квартири вільні й де саме. Якщо записів у бд небагато, то кожен запит це 1-2 секунди. Тобто ти б витратив 7200 або 14400 секунд, або ж 2-4 години, щоб просто у додатку відобразити всі квартири. Зазвичай люди 5 секунд не можуть почекати, а тут години)

Tip: you can use .values() method to get row and seat as a dict. Everything else you should find out by yourself ;)

MNDonut · 2024-09-03T04:33:42Z

services/order.py

+from db.models import Order, User, MovieSession
+from db.models import Ticket


why do you split this import?

MNDonut · 2024-09-03T04:34:27Z

services/order.py

+ movie_session = MovieSession.objects.get(
+ pk=ticket["movie_session"]
+ )
+ Ticket.objects.create(
+ movie_session=movie_session,
+ order=order,
+ row=ticket["row"],
+ seat=ticket["seat"]


it's better to set movie_session_id to avoid redundant sql query

MNDonut · 2024-09-03T04:35:14Z

services/order.py

+ if username:
+ orders = orders.filter(user__username=username)
+
+ return orders.order_by("-created_at")


redundant ordering taking into accout that you added ordering in Order.Meta

MNDonut · 2024-09-03T04:35:50Z

services/user.py

+ users_info["first_name"] = first_name
+ if last_name:
+ users_info["last_name"] = last_name
+ created_user = User.objects.create_user(**users_info)


don't use User model, use get_user_model() instead. Fix everywhere

MNDonut · 2024-09-03T04:36:04Z

services/user.py

+ first_name: str | None = None,
+ last_name: str | None = None,
+) -> User:
+ updated_user = User.objects.get(pk=user_id)


reuse get_user to follow DRY?

MNDonut · 2024-09-03T04:36:23Z

settings.py

 "db",
+ "django.contrib.auth",
+ "django.contrib.contenttypes",


actually the ordering must be:
default apps
your apps
third-party apps

Oleksl888 · 2024-09-03T20:10:57Z

.flake8

@@ -6,5 +6,5 @@ max-complexity = 18
 select = B,C,E,F,W,T4,B9,ANN,Q0,N8,VNE
 exclude =
 **migrations
- venv
+ .venv


please revert these changes on remote

Oleksl888 · 2024-09-03T20:11:59Z

db/models.py

 from django.db import models
+from django.db.models import UniqueConstraint
+
+from settings import AUTH_USER_MODEL


import from django,conf to ensure use of global proejct settings

Oleksl888 · 2024-09-03T20:12:20Z

db/models.py

+
+class Order(models.Model):
+ created_at = models.DateTimeField(auto_now_add=True)
+ user = models.ForeignKey(to=AUTH_USER_MODEL, on_delete=models.CASCADE)


related name missing here

Oleksl888 · 2024-09-03T20:14:37Z

db/models.py

+ seat = models.IntegerField()
+
+ def __str__(self) -> str:
+ return f"{self.movie_session.movie.title} \


please adhere to the project coding style, \ is unacceptable for breaking lines here 🧐

Oleksl888 · 2024-09-03T20:16:35Z

db/models.py

+ return f"{self.movie_session.movie.title} \
+{self.movie_session.show_time} (row: {self.row}, seat: {self.seat})"
+
+ class Meta:


As a convention in Django Meta class is defined right after fields definition

Oleksl888 · 2024-09-03T20:16:58Z

db/models.py

+
+ if not (1 <= self.seat <= self.movie_session.cinema_hall.seats_in_row):
+ errors["seat"] = (
+ f"seat number must be in available range: \


try to break lines without this symbol really

Oleksl888 · 2024-09-03T20:18:03Z

services/movie_session.py

+ movie_session = MovieSession.objects.get(pk=movie_session_id)
+ tickets = Ticket.objects.filter(movie_session=movie_session)
+ result = []
+ for row in range(1, movie_session.cinema_hall.rows + 1):
+ for seat in range(1, movie_session.cinema_hall.seats_in_row + 1):
+ if tickets.filter(
+ row=row,
+ seat=seat
+ ).exists():
+ result.append({"row": row, "seat": seat})
+ return result


do it as a one liner with .values() method wrapped in list()

Oleksl888 · 2024-09-03T20:18:58Z

services/order.py

+ pk=ticket["movie_session"]
+ )
+ Ticket.objects.create(
+ movie_session=movie_session,


you can pass movie_session_id to the manager instead of passing an object

MNDonut · 2024-09-06T08:03:10Z

manage.py

@@ -4,7 +4,7 @@


 if __name__ == "__main__":
- os.environ.setdefault("DJANGO_SETTINGS_MODULE", "settings")
+ os.environ.setdefault("DJANGO_SETTINGS_MODULE", "settings_dev")


what is the purpose of this change? did you change settings file?

MNDonut · 2024-09-06T08:06:38Z

services/movie_session.py

 movie_session = MovieSession.objects.get(pk=movie_session_id)
- tickets = Ticket.objects.filter(movie_session=movie_session)
- result = []
- for row in range(1, movie_session.cinema_hall.rows + 1):
- for seat in range(1, movie_session.cinema_hall.seats_in_row + 1):
- if tickets.filter(
- row=row,
- seat=seat
- ).exists():
- result.append({"row": row, "seat": seat})
- return result
+ result = (Ticket.objects.filter(movie_session=movie_session)
+ .values("row", "seat"))
+
+ return list(result)


you can do it using 1 orm query using movie session object + related name of tickets

Ivan-Shakhman added 2 commits September 2, 2024 15:40

Solution

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Solution

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MNDonut suggested changes Sep 3, 2024

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Season 1: Episode 2 - remake some methods with best practice

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Ivan-Shakhman requested a review from MNDonut September 3, 2024 08:39

Oleksl888 suggested changes Sep 3, 2024

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Season 2: episode 1 - many minor fixes

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Ivan-Shakhman requested a review from Oleksl888 September 4, 2024 10:57

Season 2: episode 1.2 -

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MNDonut suggested changes Sep 6, 2024

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Merge

b93eaea

Ivan-Shakhman requested a review from MNDonut September 6, 2024 08:50

MNDonut approved these changes Sep 6, 2024

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Solution #873

Solution #873

Ivan-Shakhman commented Sep 2, 2024

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MNDonut Sep 6, 2024

		fields=["movie_session", "row", "seat"],
		name="unique_ticket"

		from db.models import Order, User, MovieSession
		from db.models import Ticket

Solution #873

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Solution #873

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Ivan-Shakhman commented Sep 2, 2024

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