I have 3 models and they are as follow
class Table(models.Model):
waiter = models.ForeignKey(get_user_model(), on_delete=models.CASCADE,
related_name='restaurant_table')
table_no = models.IntegerField()
objects = TableManager()
class Order(models.Model):
customer = models.ForeignKey(Customer, on_delete=models.CASCADE)
food = models.ManyToManyField(OrderFood, related_name='ordered_food')
order_status = models.ForeignKey(OrderStatus, on_delete=models.CASCADE)
table = models.ForeignKey(Table, on_delete=models.CASCADE)
datetime = models.DateTimeField(default=now)
class OrderStatus(models.Model):
CHOOSE = (
('Received', 'Received'),
('Cooking', 'Cooking'),
('WaiterHand', 'In Waiter Hand'),
('Delivered', 'Delivered'),
('Paid', 'Payment Completed'),
('Rejected', 'Rejected')
)
status = models.CharField(max_length=30, null=False, blank=False, choices=CHOOSE)
created_at = models.DateTimeField(auto_now=True)
updated_at = models.DateTimeField()
Actually I am creating a restaurant management system. So here a restaurant has tables associated with a or more waiter. But I need a new feature that is table status. I mean when an order is actively associated with the table that means that table is booked. Actually that is not a problem as I can do that in many ways.
One way is I will count the active order associated with this table and if I found any active order I will return the table is booked.
Another way is I will add an extra field with the table that is a flag. This flag store status of tables is booked or not I mean the boolean field.
But my question is not the solution. My question which one is better or there are any other good solutions. Please explain it briefly I want to know which solution is better and why.
you can put #property function under class Table which you can use directly with any table objects, in templates also.
#property
def check_table_status(self):
status = 'Not Booked'
if self.order_set.all().exists():
status = 'Booked'
return status
Related
I have the following models:
class Shelf(models.Model):
user = models.ForeignKey(User, on_delete=models.CASCADE)
name = models.CharField(max_length=200, db_index=True)
slug = models.SlugField(max_length=200, editable=False)
games = models.ManyToManyField(Game, blank=True, through='SortedShelfGames')
objects = ShelfManager()
description = models.TextField(blank=True, null=True)
class SortedShelfGames(models.Model):
game = models.ForeignKey(Game, on_delete=models.CASCADE)
shelf = models.ForeignKey(Shelf, on_delete=models.CASCADE)
date_added = models.DateTimeField()
order = models.IntegerField(blank=True, null=True)
releases = models.ManyToManyField(Release)
objects = SortedShelfGamesManager.as_manager()
class Game(models.Model):
name = models.CharField(max_length=300, db_index=True)
sort_name = models.CharField(max_length=300, db_index=True)
...
I have a view where I want to get all of a user's SortedShelfGames, distinct on the Game relationship. I then want to be able to sort that list of SortedShelfGames on a few different fields. So right now, I'm doing the following inside of the SortedShelfGamesManager (which inherits from models.QuerySet) to get the list:
games = self.filter(
pk__in=Subquery(
self.filter(shelf__user=user).distinct('game').order_by('game', 'date_added').values('pk') # The order_by statement in here is to get the earliest date_added field for display
)
)
That works the way it's supposed to. However, whenever I try and do an order_by('game__sort_name'), the query takes forever in my python. When I'm actually trying to use it on my site, it just times out. If I take the generated SQL and just run it on my database, it returns all of my results in a fraction of a second. I can't figure out what I'm doing wrong here. The SortedShelfGames table has millions of records in it if that matters.
This is the generated SQL:
SELECT
"collection_sortedshelfgames"."id", "collection_sortedshelfgames"."game_id", "collection_sortedshelfgames"."shelf_id", "collection_sortedshelfgames"."date_added", "collection_sortedshelfgames"."order",
(SELECT U0."rating" FROM "reviews_review" U0 WHERE (U0."game_id" = "collection_sortedshelfgames"."game_id" AND U0."user_id" = 1 AND U0."main") LIMIT 1) AS "score",
"games_game"."id", "games_game"."created", "games_game"."last_updated", "games_game"."exact", "games_game"."date", "games_game"."year", "games_game"."quarter", "games_game"."month", "games_game"."name", "games_game"."sort_name", "games_game"."rating_id", "games_game"."box_art", "games_game"."description", "games_game"."slug", "games_game"."giantbomb_id", "games_game"."ignore_giantbomb", "games_game"."ignore_front_page", "games_game"."approved", "games_game"."user_id", "games_game"."last_edited_by_id", "games_game"."dlc", "games_game"."parent_game_id"
FROM
"collection_sortedshelfgames"
INNER JOIN
"games_game"
ON
("collection_sortedshelfgames"."game_id" = "games_game"."id")
WHERE
"collection_sortedshelfgames"."id"
IN (
SELECT
DISTINCT ON (U0."game_id") U0."id"
FROM
"collection_sortedshelfgames" U0
INNER JOIN
"collection_shelf" U1 ON (U0."shelf_id" = U1."id")
WHERE
U1."user_id" = 1
ORDER
BY U0."game_id" ASC, U0."date_added" ASC
)
ORDER BY
"games_game"."sort_name" ASC
I think you don't need a Subquery for this.
Here's what I ended up doing to solve this. Instead of using a Subquery, I created a list of primary keys by evaluating what I was using as the Subquery in, then feeding that into my query. It looks like this:
pks = list(self.filter(shelf__user=user).distinct('game').values_list('pk', flat=True))
games = self.filter(
pk__in=pks)
)
games = games.order_by('game__sort_name')
This ended up being pretty fast. This is essentially the same thing as the Subquery method, but whatever was going on underneath the hood in python/Django was slowing this way down.
My first question here, I've been looking around but couldn't find a solution.
I am building a reservation system, my models are
class Room(models.Model):
number = models.IntegerField()
beds = models.IntegerField()
capacity = models.IntegerField()
category = models.ForeignKey(
RoomCategory, on_delete=models.CASCADE, blank=True, null=True)
class Booking(models.Model):
room = models.ForeignKey(Room, on_delete=models.CASCADE, blank=True, null=True)
check_in = models.DateField()
check_out = models.DateField()
status = models.IntegerField(blank=True, null=True)
if request.method == 'POST':
no_disponible = "No hay habitaciones disponibles, selecciona otras fechas"
if form.is_valid():
room_list = Room.objects.filter(category=1).exclude(booking__check_in__lt=form.cleaned_data['check_out'],
booking__check_out__gt=form.cleaned_data['check_in'], booking__status__gt=0)
I am changing status when the customer confirms so I want to check if dates are available when status is not 1 (I change status to 1 once the payment is approved.
However booking__status__gt=0 doesn't seem to work here
Based on your query, you want to exclude rooms with:
Bookings with check ins that are less than the requested check out.
Bookings with check outs that are greater than the requested check in.
Bookings with status greater than 0.
Your current query is:
Room.objects.filter(category=1).exclude(
booking__check_in__lt=form.cleaned_data['check_out'],
booking__check_out__gt=form.cleaned_data['check_in'],
booking__status__gt=0,
)
This will remove all rooms that have status greater than 0, as well as rooms with invalid checkin/checkout dates, even though some of those rooms with invalid checkin/checkout dates have status as 0. This is because of how exclude works when it spans multi-valued relationships like this.
To fix this, change your query to get all the bookings with the exclusions you want by using Booking, and then compare it against the reverse relationship:
Room.objects.filter(category=1).exclude(
booking__in=Booking.objects.filter(
check_in__lt=form.cleaned_data['check_out'],
check_out__gt=form.cleaned_data['check_in'],
status__gt=0,
)
)
Have a read here to understand the behaviour of exclude in this case more.
Looking for help got stuck at a point, I am new to python and django. There ARE two payments corresponding to one order, one COLLECTION and multiple TRANSFER and i need the payment corresponding to an order whose direction is COLLECTION only NOT transfered yet so that i can initiate TRANSFER against that order
models.py
class Orders(models.Model):
id= models.AutoField(primary_key=True)
payment_gateway_code = models.CharField(max_length=20,choices=[('PAYTM','PAYTM')])
is_active = models.BooleanField(default=True)
class Payments(models.Model):
id = models.AutoField(primary_key=True)
orders = models.ForeignKey(Orders, on_delete=models.CASCADE)
direction = models.CharField(max_length=20,choices=[('COLLECTION','COLLECTION'),
('TRANSFER','TRANSFER')])
settlement_status = models.CharField(max_length=50,blank=True, null=True,choices=[('YES','YES'),
('NO','NO')])
is_active = models.BooleanField(default=True)
qualified_orders = Orders.objects.filter(payment_gateway_code='CASHFREE',
Exists(Payments.objects.filter(order=OuterRef('pk'), direction='COLLECTION',
settlement_status='YES')), ~Exists(Payments.objects.filter(order=OuterRef('pk'),
direction='TRANSFER')))
But above query is not working
What is OuterRef('pk')?
First, I'd suggest changing orders to order.
Then, the query you're trying to achieve will be something like this (Assuming order_id contains the ID of the order):
Paymen.objects.filter(order_id=order_id, direction="COLLECTION")
You can use views.py for that as follows
Models.py
class Orders(models.Model):
id= models.AutoField(primary_key=True)
payment_gateway_code = models.CharField(max_length=20,choices=[('PAYTM','PAYTM')])
is_active = models.BooleanField(default=True)
class Payments(models.Model):
id = models.AutoField(primary_key=True)
orders = models.ForeignKey(Orders, on_delete=models.CASCADE)
direction = models.CharField(max_length=20,related_name="direction",choices=[('COLLECTION','COLLECTION'),
('TRANSFER','TRANSFER')])
settlement_status = models.CharField(max_length=50,blank=True, null=True,choices=[('YES','YES'),
('NO','NO')])
is_active = models.BooleanField(default=True)
views.py
from App.models import orders, payments
#in case if you need objects of order this is for that
def orderfunc():
order = Orders.objects.all()
def paymentfunc():
payment = Payment.objects.all()
# from here you can check for what record you want using conditional operator
#if direction == COLLECTION:
#then do what you need
I'm making a program that helps log missions in a game. In each of these missions I would like to be able to select a number of astronauts that will go along with it out of the astronauts table. This is fine when I only need one, but how could I approach multiple foreign keys in a field?
I currently use a 'binary' string that specifies which astronauts are to be associated with the mission (1 refers to Jeb, but not Bill, Bob, or Val and 0001 means only Val), with the first digit specifying the astronaut with id 1 and so forth. This works, but it feels quite clunky.
Here's the model.py for the two tables in question.
class astronauts(models.Model):
name = models.CharField(max_length=200)
adddate = models.IntegerField(default=0)
experience = models.IntegerField(default=0)
career = models.CharField(max_length=9, blank=True, null=True)
alive = models.BooleanField(default=True)
def __str__(self):
return self.name
class Meta:
verbose_name_plural = "Kerbals"
class missions(models.Model):
# mission details
programid = models.ForeignKey(programs, on_delete=models.SET("Unknown"))
missionid = models.IntegerField(default=0)
status = models.ForeignKey(
missionstatuses, on_delete=models.SET("Unknown"))
plan = models.CharField(max_length=1000)
# launch
launchdate = models.IntegerField(default=0)
crewmembers = models.IntegerField(default=0)
# recovery
summary = models.CharField(max_length=1000, blank=True)
recdate = models.IntegerField(default=0)
def __str__(self):
return str(self.programid) + '-' + str(self.missionid)
class Meta:
verbose_name_plural = "Missions"
I saw a post about an 'intermediate linking table' to store the crew list but that also isn't ideal.
Thanks!
This is the use case for Django's ManyToManyField. Change the appropriate field on the missions:
class missions(models.Model):
crewmembers = models.ManyToManyField('astronauts')
You can access this from the Astronaut model side like so:
jeb = astronaut.objects.get(name='Jebediah Kerman')
crewed_missions = jeb.missions_set.all()
Or from the mission side like so:
mission = missions.objects.order_by('?')[0]
crew = mission.crewmembers.all()
This creates another table in the database, in case that is somehow a problem for you.
I wondering thinking how can i do a query for all Restaurants that have the attribute equal to some given value, and other given value in a list of delivery zones attribute.
Here is how looks my code:
models.py
class Restaurant(models.Model):
name = models.CharField(max_length=120)
delivery_zones = models.ManyToManyField('DeliveryZone', default=None)
service_type = models.CharField(max_length=25, choices=settings.SERVICE_TYPE_CHOICES, default='DELIVERY')
is_active = models.BooleanField(default=False)
class DeliveryZones(models.Model):
zone = models.CharField(max_length=25, default=None)
is_active = models.BooleanField(default=False)
views.py:
restaurants = get_list_404(
Restaurant, is_active=True,
service_type='SOME_GIVEN_SERVICE_TYPE_NAME',
delivery_zones__icontains='SOME_GIVEN_ZONE_NAME'
)
Sounds like what you are looking for is the __in lookup. Also, it is get_list_or_404, not get_list_404.
Try:
zones = DeliveryZones.objects.filter(zone='SOME_NAME', is_active=True)
restaurants = get_list_or_404(
Restaurant, is_active=True,
service_type='SOME_GIVEN_SERVICE_TYPE_NAME',
delivery_zones__in=zones
)
You can do this in a single query, which means a single database hit, by using a lookup that spans a relationship:
restaurants = get_list_or_404(
Restaurant, is_active=True,
service_type='SOME_GIVEN_SERVICE_TYPE_NAME',
delivery_zones__name='SOME_GIVEN_ZONE_NAME'
)
This will be much more efficient, especially if the possible list of DeliveryZones is quite long.