Save tax codes on the basket and order for reference (#4136)

* Add tax codes to basket and order

* Rename to tax_code

src/oscar/apps/basket/abstract_models.py

             "quantity": quantity,
             "price_excl_tax": stock_info.price.excl_tax,
             "price_currency": stock_info.price.currency,
+            "tax_code": stock_info.price.tax_code,
         }
         if stock_info.price.is_tax_known:
             defaults["price_incl_tax"] = stock_info.price.incl_tax
     price_incl_tax = models.DecimalField(
         _("Price incl. Tax"), decimal_places=2, max_digits=12, null=True
     )
+    tax_code = models.CharField(
+        _("VAT rate code"), max_length=64, blank=True, null=True
+    )
 
     # Track date of first addition
     date_created = models.DateTimeField(

src/oscar/apps/basket/migrations/0012_line_code.py

+# Generated by Django 3.2.19 on 2023-07-10 08:31
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('basket', '0011_json_basket_option'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='line',
+            name='tax_code',
+            field=models.CharField(blank=True, max_length=64, null=True, verbose_name='VAT rate code'),
+        ),
+    ]

src/oscar/apps/order/abstract_models.py

     shipping_excl_tax = models.DecimalField(
         _("Shipping charge (excl. tax)"), decimal_places=2, max_digits=12, default=0
     )
+    shipping_tax_code = models.CharField(
+        _("Shipping VAT rate code"), max_length=64, blank=True, null=True
+    )
 
     # Not all lines are actually shipped (such as downloads), hence shipping
     # address is not mandatory.
         null=True,
     )
 
+    tax_code = models.CharField(
+        _("VAT rate code"), max_length=64, blank=True, null=True
+    )
+
     # Partners often want to assign some status to each line to help with their
     # own business processes.
     status = models.CharField(_("Status"), max_length=255, blank=True)
     shipping_excl_tax = models.DecimalField(
         _("Shipping (excl. tax)"), decimal_places=2, max_digits=12, default=0
     )
+    tax_code = models.CharField(
+        _("VAT rate code"), max_length=64, blank=True, null=True
+    )
 
     class Meta:
         abstract = True
     incl_tax = models.DecimalField(
         _("Surcharge (inc. tax)"), decimal_places=2, max_digits=12, default=0
     )
-
     excl_tax = models.DecimalField(
         _("Surcharge (excl. tax)"), decimal_places=2, max_digits=12, default=0
     )
+    tax_code = models.CharField(
+        _("VAT rate code"), max_length=64, blank=True, null=True
+    )
 
     @property
     def tax(self):

src/oscar/apps/order/migrations/0014_tax_code.py

+# Generated by Django 3.2.19 on 2023-07-10 08:44
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('order', '0013_json_option_value'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='line',
+            name='tax_code',
+            field=models.CharField(blank=True, max_length=64, null=True, verbose_name='VAT rate code'),
+        ),
+        migrations.AddField(
+            model_name='lineprice',
+            name='tax_code',
+            field=models.CharField(blank=True, max_length=64, null=True, verbose_name='VAT rate code'),
+        ),
+        migrations.AddField(
+            model_name='order',
+            name='shipping_tax_code',
+            field=models.CharField(blank=True, max_length=64, null=True, verbose_name='Shipping VAT rate code'),
+        ),
+        migrations.AddField(
+            model_name='surcharge',
+            name='tax_code',
+            field=models.CharField(blank=True, max_length=64, null=True, verbose_name='VAT rate code'),
+        ),
+    ]

src/oscar/apps/order/utils.py

             "total_excl_tax": total.excl_tax,
             "shipping_incl_tax": shipping_charge.incl_tax,
             "shipping_excl_tax": shipping_charge.excl_tax,
+            "shipping_tax_code": shipping_charge.tax_code,
             "shipping_method": shipping_method.name,
             "shipping_code": shipping_method.code,
         }
                     code=charge.surcharge.code,
                     excl_tax=charge.price.excl_tax,
                     incl_tax=charge.price.incl_tax,
+                    tax_code=charge.price.tax_code,
                 )
+
         return order
 
     def create_line_models(self, order, basket_line, extra_line_fields=None):
             raise exceptions.UnableToPlaceOrder(
                 "Basket line #%d has no stockrecord" % basket_line.id
             )
+
         partner = stockrecord.partner
         line_data = {
             "order": order,
             # Reporting details
             "unit_price_incl_tax": basket_line.unit_price_incl_tax,
             "unit_price_excl_tax": basket_line.unit_price_excl_tax,
+            "tax_code": basket_line.tax_code,
         }
         extra_line_fields = extra_line_fields or {}
         if hasattr(settings, "OSCAR_INITIAL_LINE_STATUS"):
                 quantity=quantity,
                 price_incl_tax=price_incl_tax,
                 price_excl_tax=price_excl_tax,
+                tax_code=basket_line.tax_code,
             )
 
     # pylint: disable=unused-argument

src/oscar/apps/partner/prices.py

     #: Price tax
     tax = None
 
+    # Code used to store the vat rate reference
+    tax_code = None
+
     #: Retail price
     retail = None
 
 
     exists = True
 
-    def __init__(self, currency, excl_tax, tax=None):
+    def __init__(self, currency, excl_tax, tax=None, tax_code=None):
         super().__init__()
         self.currency = currency
         self.excl_tax = excl_tax
         self.tax = tax
+        self.tax_code = tax_code
 
     @property
     def incl_tax(self):

src/oscar/core/prices.py

         currency (str): 3 character currency code
     """
 
-    def __init__(self, currency, excl_tax, incl_tax=None, tax=None):
+    def __init__(self, currency, excl_tax, incl_tax=None, tax=None, tax_code=None):
         self.currency = currency
         self.excl_tax = excl_tax
+        self.tax_code = tax_code
         if incl_tax is not None:
             self.incl_tax = incl_tax
             self.is_tax_known = True
             currency=self.currency,
             incl_tax=self.incl_tax + other.incl_tax,
             excl_tax=self.excl_tax + other.excl_tax,
+            tax_code=self.tax_code,
         )
 
     def __radd__(self, other):