forked from CGM_Public/pretix_original
392 lines
17 KiB
Python
392 lines
17 KiB
Python
from collections import Counter, namedtuple
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from datetime import timedelta
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from decimal import Decimal
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from typing import List, Optional
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from celery.exceptions import MaxRetriesExceededError
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from django.db import transaction
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from django.db.models import Q
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from django.utils.timezone import now
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from django.utils.translation import ugettext as _
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from pretix.base.i18n import LazyLocaleException
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from pretix.base.models import (
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CartPosition, Event, Item, ItemVariation, Voucher,
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)
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from pretix.base.services.async import ProfiledTask
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from pretix.base.services.locking import LockTimeoutException
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from pretix.celery_app import app
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class CartError(LazyLocaleException):
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pass
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error_messages = {
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'busy': _('We were not able to process your request completely as the '
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'server was too busy. Please try again.'),
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'empty': _('You did not select any products.'),
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'not_for_sale': _('You selected a product which is not available for sale.'),
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'unavailable': _('Some of the products you selected are no longer available. '
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'Please see below for details.'),
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'in_part': _('Some of the products you selected are no longer available in '
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'the quantity you selected. Please see below for details.'),
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'max_items': _("You cannot select more than %s items per order."),
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'not_started': _('The presale period for this event has not yet started.'),
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'ended': _('The presale period has ended.'),
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'price_too_high': _('The entered price is to high.'),
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'voucher_invalid': _('This voucher code is not known in our database.'),
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'voucher_redeemed': _('This voucher code has already been used the maximum number of times allowed.'),
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'voucher_redeemed_partial': _('This voucher code can only be redeemed %d more times.'),
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'voucher_double': _('You already used this voucher code. Remove the associated line from your '
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'cart if you want to use it for a different product.'),
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'voucher_expired': _('This voucher is expired.'),
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'voucher_invalid_item': _('This voucher is not valid for this product.'),
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'voucher_required': _('You need a valid voucher code to order this product.'),
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}
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class CartManager:
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AddOperation = namedtuple('AddOperation', ('count', 'item', 'variation', 'price', 'voucher', 'quotas'))
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RemoveOperation = namedtuple('RemoveOperation', ('position',))
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ExtendOperation = namedtuple('ExtendOperation', ('position', 'count', 'item', 'variation', 'price', 'voucher',
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'quotas'))
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order = {
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RemoveOperation: 10,
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ExtendOperation: 20,
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AddOperation: 30
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}
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def __init__(self, event: Event, cart_id: str):
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self.event = event
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self.cart_id = cart_id
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self.now_dt = now()
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self._operations = []
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self._quota_diff = Counter()
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self._voucher_use_diff = Counter()
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self._items_cache = {}
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self._variations_cache = {}
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self._expiry = None
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@property
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def positions(self):
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return CartPosition.objects.filter(
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Q(cart_id=self.cart_id) & Q(event=self.event)
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)
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def _calculate_expiry(self):
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self._expiry = self.now_dt + timedelta(minutes=self.event.settings.get('reservation_time', as_type=int))
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def _check_presale_dates(self):
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if self.event.presale_start and self.now_dt < self.event.presale_start:
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raise CartError(error_messages['not_started'])
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if self.event.presale_end and self.now_dt > self.event.presale_end:
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raise CartError(error_messages['ended'])
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def _extend_expiry_of_valid_existing_positions(self):
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# Extend this user's cart session to ensure all items in the cart expire at the same time
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# We can extend the reservation of items which are not yet expired without risk
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self.positions.filter(expires__gt=self.now_dt).update(expires=self._expiry)
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def _delete_expired(self, expired: List[CartPosition]):
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for cp in expired:
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if cp.expires <= self.now_dt:
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cp.delete()
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def _update_items_cache(self, item_ids: List[int], variation_ids: List[int]):
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self._items_cache.update(
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{i.pk: i for i in self.event.items.prefetch_related('quotas').filter(
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id__in=[i for i in item_ids if i and i not in self._items_cache]
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)}
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)
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self._variations_cache.update(
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{v.pk: v for v in
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ItemVariation.objects.filter(item__event=self.event).prefetch_related(
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'quotas'
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).select_related('item', 'item__event').filter(
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id__in=[i for i in variation_ids if i and i not in self._variations_cache]
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)}
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)
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def _check_max_cart_size(self):
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cartsize = self.positions.count()
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cartsize += sum([op.count for op in self._operations if isinstance(op, self.AddOperation)])
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cartsize -= len([1 for op in self._operations if isinstance(op, self.RemoveOperation)])
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if cartsize > int(self.event.settings.max_items_per_order):
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# TODO: i18n plurals
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raise CartError(error_messages['max_items'], (self.event.settings.max_items_per_order,))
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def _check_item_constraints(self, op):
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if isinstance(op, self.AddOperation) or isinstance(op, self.ExtendOperation):
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if op.item.require_voucher and op.voucher is None:
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raise CartError(error_messages['voucher_required'])
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if op.item.hide_without_voucher and (op.voucher is None or op.voucher.item is None or op.voucher.item.pk != op.item.pk):
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raise CartError(error_messages['voucher_required'])
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if not op.item.is_available() or (op.variation and not op.variation.active):
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raise CartError(error_messages['unavailable'])
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if op.voucher and not op.voucher.applies_to(op.item, op.variation):
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raise CartError(error_messages['voucher_invalid_item'])
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def _get_price(self, item: Item, variation: Optional[ItemVariation],
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voucher: Optional[Voucher], custom_price: Optional[Decimal]):
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price = item.default_price if variation is None else (
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variation.default_price if variation.default_price is not None else item.default_price
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)
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if voucher:
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price = voucher.calculate_price(price)
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if item.free_price and custom_price is not None and custom_price != "":
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if not isinstance(custom_price, Decimal):
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custom_price = Decimal(custom_price.replace(",", "."))
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if custom_price > 100000000:
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return error_messages['price_too_high']
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price = max(custom_price, price)
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return price
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def extend_expired_positions(self):
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expired = self.positions.filter(expires__lte=self.now_dt).select_related(
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'item', 'variation', 'voucher'
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).prefetch_related('item__quotas', 'variation__quotas')
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for cp in expired:
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price = self._get_price(cp.item, cp.variation, cp.voucher, cp.price)
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quotas = list(cp.item.quotas.all()) if cp.variation is None else list(cp.variation.quotas.all())
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if not quotas:
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raise CartError(error_messages['unavailable'])
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if not cp.voucher or (not cp.voucher.allow_ignore_quota and not cp.voucher.block_quota):
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for quota in quotas:
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self._quota_diff[quota] += 1
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else:
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quotas = []
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op = self.ExtendOperation(
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position=cp, item=cp.item, variation=cp.variation, voucher=cp.voucher, count=1,
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price=price, quotas=quotas
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)
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self._check_item_constraints(op)
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if cp.voucher:
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self._voucher_use_diff[cp.voucher] += 1
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self._operations.append(op)
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def add_new_items(self, items: List[dict]):
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# Fetch items from the database
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self._update_items_cache([i['item'] for i in items], [i['variation'] for i in items])
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quota_diff = Counter()
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voucher_use_diff = Counter()
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operations = []
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for i in items:
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# Check whether the specified items are part of what we just fetched from the database
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# If they are not, the user supplied item IDs which either do not exist or belong to
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# a different event
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if i['item'] not in self._items_cache or (i['variation'] and i['variation'] not in self._variations_cache):
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raise CartError(error_messages['not_for_sale'])
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item = self._items_cache[i['item']]
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variation = self._variations_cache[i['variation']] if i['variation'] is not None else None
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voucher = None
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if i.get('voucher'):
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try:
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voucher = self.event.vouchers.get(code=i.get('voucher').strip())
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except Voucher.DoesNotExist:
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raise CartError(error_messages['voucher_invalid'])
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else:
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voucher_use_diff[voucher] += i['count']
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# Fetch all quotas. If there are no quotas, this item is not allowed to be sold.
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quotas = list(item.quotas.all()) if variation is None else list(variation.quotas.all())
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if not quotas:
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raise CartError(error_messages['unavailable'])
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if not voucher or (not voucher.allow_ignore_quota and not voucher.block_quota):
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for quota in quotas:
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quota_diff[quota] += i['count']
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else:
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quotas = []
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price = self._get_price(item, variation, voucher, i.get('price'))
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op = self.AddOperation(
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count=i['count'], item=item, variation=variation, price=price, voucher=voucher, quotas=quotas
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)
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self._check_item_constraints(op)
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operations.append(op)
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self._quota_diff += quota_diff
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self._voucher_use_diff += voucher_use_diff
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self._operations += operations
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def remove_items(self, items: List[dict]):
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# TODO: We could calculate quotadiffs and voucherdiffs here, which would lead to more
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# flexible usages (e.g. a RemoveOperation and an AddOperation in the same transaction
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# could cancel each other out quota-wise). However, we are not taking this performance
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# penalty for now as there is currently no outside interface that would allow building
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# such a transaction.
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for i in items:
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cw = Q(cart_id=self.cart_id) & Q(item_id=i['item']) & Q(event=self.event)
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if i['variation']:
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cw &= Q(variation_id=i['variation'])
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else:
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cw &= Q(variation__isnull=True)
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# Prefer to delete positions that have the same price as the one the user clicked on, after thet
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# prefer the most expensive ones.
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cnt = i['count']
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if i['price']:
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correctprice = CartPosition.objects.filter(cw).filter(price=Decimal(i['price'].replace(",", ".")))[:cnt]
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for cp in correctprice:
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self._operations.append(self.RemoveOperation(position=cp))
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cnt -= len(correctprice)
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if cnt > 0:
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for cp in CartPosition.objects.filter(cw).order_by("-price")[:cnt]:
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self._operations.append(self.RemoveOperation(position=cp))
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def _get_quota_availability(self):
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quotas_ok = {}
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for quota, count in self._quota_diff.items():
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avail = quota.availability(self.now_dt)
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if avail[1] is not None and avail[1] < count:
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quotas_ok[quota] = min(count, avail[1])
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else:
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quotas_ok[quota] = count
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return quotas_ok
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def _get_voucher_availability(self):
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vouchers_ok = {}
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for voucher, count in self._voucher_use_diff.items():
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voucher.refresh_from_db()
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if voucher.valid_until is not None and voucher.valid_until < self.now_dt:
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raise CartError(error_messages['voucher_expired'])
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redeemed_in_carts = CartPosition.objects.filter(
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Q(voucher=voucher) & Q(event=self.event) &
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Q(expires__gte=self.now_dt)
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).exclude(pk__in=[
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op.position.voucher_id for op in self._operations if isinstance(op, self.ExtendOperation)
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])
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v_avail = voucher.max_usages - voucher.redeemed - redeemed_in_carts.count()
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vouchers_ok[voucher] = v_avail
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return vouchers_ok
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def _perform_operations(self):
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vouchers_ok = self._get_voucher_availability()
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quotas_ok = self._get_quota_availability()
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err = None
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new_cart_positions = []
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self._operations.sort(key=lambda a: self.order[type(a)])
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for op in self._operations:
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if isinstance(op, self.RemoveOperation):
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op.position.delete()
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elif isinstance(op, self.AddOperation) or isinstance(op, self.ExtendOperation):
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# Create a CartPosition for as much items as we can
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requested_count = quota_available_count = voucher_available_count = op.count
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if op.quotas:
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quota_available_count = min(requested_count, min(quotas_ok[q] for q in op.quotas))
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if op.voucher:
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voucher_available_count = min(voucher_available_count, vouchers_ok[op.voucher])
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if quota_available_count < 1:
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err = err or error_messages['unavailable']
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elif quota_available_count < requested_count:
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err = err or error_messages['in_part']
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if voucher_available_count < 1:
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err = err or error_messages['voucher_redeemed']
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elif voucher_available_count < requested_count:
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err = err or error_messages['voucher_redeemed_partial'] % voucher_available_count
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available_count = min(quota_available_count, voucher_available_count)
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for q in op.quotas:
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quotas_ok[q] -= available_count
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if op.voucher:
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vouchers_ok[op.voucher] -= available_count
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if isinstance(op, self.AddOperation):
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for k in range(available_count):
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new_cart_positions.append(CartPosition(
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event=self.event, item=op.item, variation=op.variation,
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price=op.price, expires=self._expiry,
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cart_id=self.cart_id, voucher=op.voucher
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))
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elif isinstance(op, self.ExtendOperation):
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if available_count == 1:
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op.position.expires = self._expiry
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op.position.price = op.price
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op.position.save()
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elif available_count == 0:
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op.position.delete()
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else:
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raise AssertionError("ExtendOperation cannot affect more than one item")
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CartPosition.objects.bulk_create(new_cart_positions)
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return err
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def commit(self):
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self._check_presale_dates()
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self._check_max_cart_size()
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self._calculate_expiry()
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with self.event.lock() as now_dt:
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with transaction.atomic():
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self.now_dt = now_dt
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self._extend_expiry_of_valid_existing_positions()
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self.extend_expired_positions()
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err = self._perform_operations()
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if err:
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raise CartError(err)
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@app.task(base=ProfiledTask, bind=True, max_retries=5, default_retry_delay=1, throws=(CartError,))
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def add_items_to_cart(self, event: int, items: List[dict], cart_id: str=None) -> None:
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"""
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Adds a list of items to a user's cart.
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:param event: The event ID in question
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:param items: A list of tuple of the form (item id, variation id or None, number, custom_price, voucher)
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:param session: Session ID of a guest
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:param coupon: A coupon that should also be reeemed
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:raises CartError: On any error that occured
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"""
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event = Event.objects.get(id=event)
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try:
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try:
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cm = CartManager(event=event, cart_id=cart_id)
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cm.add_new_items(items)
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cm.commit()
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except LockTimeoutException:
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self.retry()
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except (MaxRetriesExceededError, LockTimeoutException):
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raise CartError(error_messages['busy'])
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@app.task(base=ProfiledTask, bind=True, max_retries=5, default_retry_delay=1, throws=(CartError,))
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def remove_items_from_cart(self, event: int, items: List[dict], cart_id: str=None) -> None:
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"""
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Removes a list of items from a user's cart.
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:param event: The event ID in question
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:param items: A list of tuple of the form (item id, variation id or None, number)
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:param session: Session ID of a guest
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"""
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event = Event.objects.get(id=event)
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try:
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try:
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cm = CartManager(event=event, cart_id=cart_id)
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cm.remove_items(items)
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cm.commit()
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except LockTimeoutException:
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self.retry()
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except (MaxRetriesExceededError, LockTimeoutException):
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raise CartError(error_messages['busy'])
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