Source code for

from __future__ import absolute_import, unicode_literals

import random
from datetime import date
from decimal import Decimal

from django.core.exceptions import ValidationError
from django.db import models
from django.db.models import ObjectDoesNotExist, Q
from django.utils.encoding import python_2_unicode_compatible
from django.utils.translation import ugettext_lazy as _

import plata
from plata.fields import CurrencyField, JSONField
from import Order, TaxClass

[docs]@python_2_unicode_compatible class DiscountBase(models.Model): """Base class for discounts and applied discounts""" AMOUNT_VOUCHER_EXCL_TAX = 10 AMOUNT_VOUCHER_INCL_TAX = 20 PERCENTAGE_VOUCHER = 30 MEANS_OF_PAYMENT = 40 TYPE_CHOICES = ( ( AMOUNT_VOUCHER_EXCL_TAX, _("amount voucher excl. tax (reduces total tax on order)"), ), ( AMOUNT_VOUCHER_INCL_TAX, _("amount voucher incl. tax (reduces total tax on order)"), ), (PERCENTAGE_VOUCHER, _("percentage voucher (reduces total tax on order)")), (MEANS_OF_PAYMENT, _("means of payment (does not change total tax on order)")), ) #: You can add and remove options at will, except for 'all': This option #: must always be available, and it cannot have any form fields CONFIG_OPTIONS = [ ("all", {"title": _("All products")}), ( "exclude_sale", { "title": _("Exclude sale prices"), "orderitem_query": lambda **values: Q(is_sale=False), }, ), ] name = models.CharField(_("name"), max_length=100) type = models.PositiveIntegerField(_("type"), choices=TYPE_CHOICES) value = models.DecimalField(_("value"), max_digits=18, decimal_places=10) currency = CurrencyField( blank=True, null=True, help_text=_("Only required for amount discounts.") ) tax_class = models.ForeignKey( TaxClass, on_delete=models.CASCADE, verbose_name=_("tax class"), blank=True, null=True, help_text=_("Only required for amount discounts incl. tax."), ) config = JSONField( _("configuration"), blank=True, help_text=_("If you edit this field directly, changes below will be ignored."), default=dict, ) class Meta: abstract = True def __str__(self): return def save(self, *args, **kwargs): self.full_clean() super(DiscountBase, self).save(*args, **kwargs) save.alters_data = True def clean(self): if self.type == self.PERCENTAGE_VOUCHER: if self.currency or self.tax_class: raise ValidationError( _("Percentage discounts cannot have currency and tax class set.") ) elif self.type == self.AMOUNT_VOUCHER_EXCL_TAX: if not self.currency: raise ValidationError(_("Amount discounts excl. tax need a currency.")) if self.tax_class: raise ValidationError( _("Amount discounts excl. tax cannot have tax class set.") ) elif self.type == self.AMOUNT_VOUCHER_INCL_TAX: if not (self.currency and self.tax_class): raise ValidationError( _("Amount discounts incl. tax need a currency and a tax class.") ) elif self.type == self.MEANS_OF_PAYMENT: if not self.currency: raise ValidationError(_("Means of payment need a currency.")) if self.tax_class: raise ValidationError(_("Means of payment cannot have tax class set.")) else: raise ValidationError(_("Unknown discount type.")) def _eligible_products(self, order, items): """ Return a list of products which are eligible for discounting using the discount configuration. """ product_model = plata.product_model() products = product_model._default_manager.filter( id__in=[item.product_id for item in items] ) orderitems = order.items.model._default_manager.filter( id__in=[ for item in items] ) for key, parameters in self.config.items(): parameters = dict((str(k), v) for k, v in parameters.items()) cfg = dict(self.CONFIG_OPTIONS)[key] if "product_query" in cfg: products = products.filter(cfg["product_query"](**parameters)) if "orderitem_query" in cfg: orderitems = orderitems.filter(cfg["orderitem_query"](**parameters)) return products.filter(id__in=orderitems.values("product_id")) def apply(self, order, items, **kwargs): if not items: return if self.type == self.AMOUNT_VOUCHER_EXCL_TAX: self._apply_amount_discount(order, items, tax_included=False) elif self.type == self.AMOUNT_VOUCHER_INCL_TAX: self._apply_amount_discount(order, items, tax_included=True) elif self.type == self.PERCENTAGE_VOUCHER: self._apply_percentage_discount(order, items) elif self.type == self.MEANS_OF_PAYMENT: self._apply_means_of_payment(order, items) else: raise NotImplementedError("Unknown discount type %s" % self.type) def _apply_amount_discount(self, order, items, tax_included): """ Apply amount discount evenly to all eligible order items Aggregates remaining discount (if discount is bigger than order total) """ eligible_products = self._eligible_products(order, items).values_list( "id", flat=True ) eligible_items = [ item for item in items if item.product_id in eligible_products ] if tax_included: discount = self.value / (1 + self.tax_class.rate / 100) else: discount = self.value items_subtotal = sum( [item.discounted_subtotal_excl_tax for item in eligible_items], Decimal("0.00"), ) # Don't allow bigger discounts than the items subtotal if discount > items_subtotal: self.remaining = (discount - items_subtotal).quantize(Decimal("0E-10")) discount = items_subtotal for item in eligible_items: item._line_item_discount += ( item.discounted_subtotal_excl_tax / items_subtotal * discount ) def _apply_means_of_payment(self, order, items): items_tax = sum((item._line_item_tax for item in items), Decimal("0.00")) for item in items: items_tax discount = self.value # items_subtotal = order.subtotal if \ # order.price_includes_tax else order.subtotal + items_tax # CHECK: items_subtotal is unused! # Don't allow bigger discounts than the items subtotal remaining = discount for item in items: if order.price_includes_tax: items_subtotal_inkl_taxes = item.subtotal # items_subtotal_excl_taxes = item._unit_price * item.quantity else: items_subtotal_inkl_taxes = item.subtotal + item._line_item_tax # items_subtotal_excl_taxes = item.subtotal # CHECK: items_subtotal_excl_taxes is unused! if remaining >= items_subtotal_inkl_taxes - item._line_item_discount: if item._line_item_discount < items_subtotal_inkl_taxes: new_discount = items_subtotal_inkl_taxes - item._line_item_discount item._line_item_discount += new_discount remaining -= new_discount else: item._line_item_discount += remaining remaining = 0 self.remaining = remaining def _apply_percentage_discount(self, order, items): """ Apply percentage discount evenly to all eligible order items """ eligible_products = self._eligible_products(order, items).values_list( "id", flat=True ) factor = self.value / 100 for item in items: if item.product_id not in eligible_products: continue item._line_item_discount += item.discounted_subtotal_excl_tax * factor
# Nearly all letters and digits, excluding those which can be easily confounded RANDOM_CODE_CHARACTERS = "23456789abcdefghijkmnopqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ" def generate_random_code(): return "".join(random.sample(RANDOM_CODE_CHARACTERS, 10))
[docs]class Discount(DiscountBase): code = models.CharField( _("code"), max_length=30, unique=True, default=generate_random_code ) is_active = models.BooleanField(_("is active"), default=True) valid_from = models.DateField(_("valid from"), valid_until = models.DateField(_("valid until"), blank=True, null=True) allowed_uses = models.IntegerField( _("number of allowed uses"), blank=True, null=True, help_text=_( "Leave empty if there is no limit on the number of uses" " of this discount." ), ) used = models.IntegerField(_("number of times already used"), default=0) class Meta: verbose_name = _("discount") verbose_name_plural = _("discounts")
[docs] def validate(self, order): """ Validate whether this discount can be applied on the given order """ messages = [] if not self.is_active: messages.append(_("Discount is inactive.")) today = if today < self.valid_from: messages.append(_("Discount is not active yet.")) if self.valid_until and today > self.valid_until: messages.append(_("Discount is expired.")) if self.allowed_uses and self.used >= self.allowed_uses: messages.append( _("Allowed uses for this discount has already been reached.") ) if self.currency != order.currency and self.type in ( self.AMOUNT_VOUCHER_EXCL_TAX, self.AMOUNT_VOUCHER_INCL_TAX, self.MEANS_OF_PAYMENT, ): messages.append(_("Discount and order currencies do not match.")) if messages: raise ValidationError(messages) return True
[docs] def add_to(self, order, recalculate=True): """ Add discount to passed order Removes the previous discount if a discount with this code has already been added to the order before. """ self.validate(order) try: order.applied_discounts.get(code=self.code).delete() except ObjectDoesNotExist: pass instance = order.applied_discounts.create( code=self.code, type=self.type,, value=self.value, currency=self.currency, tax_class=self.tax_class, config=self.config, ) if recalculate: order.recalculate_total() return instance
[docs]class AppliedDiscountManager(models.Manager): """ Default manager for the ``AppliedDiscount`` model """
[docs] def remaining(self, order=None): """ Calculate remaining discount excl. tax Can either be used as related manager:: order.applied_discounts.remaining() or directly:: AppliedDiscount.objects.remaining(order) """ queryset = self.all() if order: queryset = queryset.filter(order=order) return sum((d.remaining for d in queryset), Decimal("0.00"))
[docs]class AppliedDiscount(DiscountBase): """ Stores an applied discount, so that deletion of discounts does not affect orders. """ order = models.ForeignKey( Order, on_delete=models.CASCADE, related_name="applied_discounts", verbose_name=_("order"), ) # We could make this a ForeignKey to Discount.code, but we do not # want deletions to cascade to this table and we still need the code # for the PDF generation or whatever anyway. code = models.CharField(_("code"), max_length=30) remaining = models.DecimalField( _("remaining"), max_digits=18, decimal_places=10, default=0, help_text=_( "Discount amount excl. tax remaining after discount has been applied." ), ) class Meta: ordering = ["type", "name"] verbose_name = _("applied discount") verbose_name_plural = _("applied discounts") objects = AppliedDiscountManager()