Allow variations to override item meta data (#2965)

src/pretix/base/models/__init__.py

@@ -34,8 +34,8 @@ from .giftcards import GiftCard, GiftCardAcceptance, GiftCardTransaction
 from .invoices import Invoice, InvoiceLine, invoice_filename
 from .items import (
     Item, ItemAddOn, ItemBundle, ItemCategory, ItemMetaProperty, ItemMetaValue,
-    ItemVariation, Question, QuestionOption, Quota, SubEventItem,
-    SubEventItemVariation, itempicture_upload_to,
+    ItemVariation, ItemVariationMetaValue, Question, QuestionOption, Quota,
+    SubEventItem, SubEventItemVariation, itempicture_upload_to,
 )
 from .log import LogEntry
 from .memberships import Membership, MembershipType

src/pretix/base/models/event.py

@@ -728,7 +728,7 @@ class Event(EventMixin, LoggedModel):
         from ..signals import event_copy_data
         from . import (
             Discount, Item, ItemAddOn, ItemBundle, ItemCategory, ItemMetaValue,
-            Question, Quota,
+            ItemVariationMetaValue, Question, Quota,
         )
 
         #  Note: avoid self.set_active_plugins(), it causes trouble e.g. for the badges plugin.
@@ -804,12 +804,18 @@ class Event(EventMixin, LoggedModel):
                 v.item = i
                 v.save(force_insert=True)
 
-        for imv in ItemMetaValue.objects.filter(item__event=other).prefetch_related('item', 'property'):
+        for imv in ItemMetaValue.objects.filter(item__event=other):
             imv.pk = None
-            imv.property = item_meta_properties_map[imv.property.pk]
+            imv.property = item_meta_properties_map[imv.property_id]
             imv.item = item_map[imv.item.pk]
             imv.save(force_insert=True)
 
+        for imv in ItemVariationMetaValue.objects.filter(variation__item__event=other):
+            imv.pk = None
+            imv.property = item_meta_properties_map[imv.property_id]
+            imv.variation = variation_map[imv.variation_id]
+            imv.save(force_insert=True)
+
         for ia in ItemAddOn.objects.filter(base_item__event=other).prefetch_related('base_item', 'addon_category'):
             ia.pk = None
             ia.base_item = item_map[ia.base_item.pk]

src/pretix/base/models/items.py

@@ -1008,6 +1008,16 @@ class ItemVariation(models.Model):
             return False
         return True
 
+    @property
+    def meta_data(self):
+        data = self.item.meta_data
+        if hasattr(self, 'meta_values_cached'):
+            data.update({v.property.name: v.value for v in self.meta_values_cached})
+        else:
+            data.update({v.property.name: v.value for v in self.meta_values.select_related('property').all()})
+
+        return OrderedDict((k, v) for k, v in sorted(data.items(), key=lambda k: k[0]))
+
 
 class ItemAddOn(models.Model):
     """
@@ -1787,8 +1797,21 @@ class ItemMetaValue(LoggedModel):
     class Meta:
         unique_together = ('item', 'property')
 
-    def delete(self, *args, **kwargs):
-        super().delete(*args, **kwargs)
 
-    def save(self, *args, **kwargs):
-        super().save(*args, **kwargs)
+class ItemVariationMetaValue(LoggedModel):
+    """
+    A meta-data value assigned to an item variation, overriding the value on the item.
+
+    :param variation: The variation this metadata is valid for
+    :type variation: ItemVariation
+    :param property: The property this value belongs to
+    :type property: ItemMetaProperty
+    :param value: The actual value
+    :type value: str
+    """
+    variation = models.ForeignKey('ItemVariation', on_delete=models.CASCADE, related_name='meta_values')
+    property = models.ForeignKey('ItemMetaProperty', on_delete=models.CASCADE, related_name='variation_values')
+    value = models.TextField()
+
+    class Meta:
+        unique_together = ('variation', 'property')