Add Item.get_all_variations and a test for it

src/tixlbase/models.py

@@ -1,3 +1,5 @@
+from itertools import product
+
 from django.db import models
 from django.conf import settings
 from django.contrib.auth.models import AbstractBaseUser, BaseUserManager, PermissionsMixin
@@ -462,6 +464,39 @@ class Item(models.Model):
         self.active = False
         return super().save()
 
+    def get_all_variations(self):
+        """
+        This method returns a list containing all variations of this
+        item, where n is the number of properties connected to this
+        item. The list contains either tupels of PropertyValue objects
+        or ItemVariation objects. The returned list is assumed not to
+        be in any order.
+        """
+        all_variations = self.variations.all().prefetch_related("values")
+        all_properties = self.properties.all().prefetch_related("values")
+        variations_cache = {}
+        for var in all_variations:
+            key = []
+            for v in var.values.all():
+                key.append((v.prop.pk, v.pk))
+            key = hash(tuple(sorted(key)))
+            variations_cache[key] = var
+
+        result = []
+        for comb in product(*[prop.values.all() for prop in all_properties]):
+            if len(comb) == 0:
+                continue
+            key = []
+            for v in comb:
+                key.append((v.prop.pk, v.pk))
+            key = hash(tuple(sorted(key)))
+            if key in variations_cache:
+                result.append(variations_cache[key])
+            else:
+                result.append(comb)
+
+        return result
+
     class Meta:
         verbose_name = _("Item")
         verbose_name_plural = _("Items")

src/tixlbase/tests.py

@@ -1,3 +1,92 @@
 from django.test import TestCase
+from django.utils.timezone import now
 
-# Create your tests here.
+from tixlbase.models import (
+    Event, Organizer, Item, ItemVariation,
+    Property, PropertyValue
+)
+
+
+class ItemVariationsTest(TestCase):
+    """
+    This test case tests various methods around the properties /
+    variations concept.
+    """
+
+    def setUp(self):
+        o = Organizer.objects.create(name='Dummy', slug='dummy')
+        e = Event.objects.create(
+            organizer=o, name='Dummy', slug='dummy',
+            date_from=now(),
+        )
+        p = Property.objects.create(event=e, name='Size')
+        PropertyValue.objects.create(prop=p, value='S')
+        PropertyValue.objects.create(prop=p, value='M')
+        PropertyValue.objects.create(prop=p, value='L')
+        p = Property.objects.create(event=e, name='Color')
+        PropertyValue.objects.create(prop=p, value='black')
+        PropertyValue.objects.create(prop=p, value='blue')
+
+    def test_get_all_variations(self):
+        e = Event.objects.get(name='Dummy', organizer__name='Dummy')
+        i = Item.objects.create(event=e, name='Dummy')
+
+        # No properties available
+        v = i.get_all_variations()
+        self.assertEqual(len(v), 0)
+
+        # One property, no variations
+        p = Property.objects.get(event=e, name='Size')
+        i.properties.add(p)
+        v = i.get_all_variations()
+        self.assertIs(type(v), list)
+        self.assertEqual(len(v), 3)
+        values = []
+        for var in v:
+            self.assertIs(type(var), tuple)
+            self.assertIs(type(var[0]), PropertyValue)
+            values.append(var[0].value)
+        self.assertEqual(sorted(values), sorted(['S', 'M', 'L']))
+
+        # One property, one variation
+        iv = ItemVariation.objects.create(item=i)
+        iv.values.add(PropertyValue.objects.get(prop=p, value='S'))
+        v = i.get_all_variations()
+        self.assertIs(type(v), list)
+        self.assertEqual(len(v), 3)
+        values = []
+        for var in v:
+            if type(var) == ItemVariation:
+                self.assertEqual(iv.pk, var.pk)
+                values.append(iv.values.all()[0].value)
+            elif type(var) == tuple:
+                self.assertIs(type(var[0]), PropertyValue)
+                values.append(var[0].value)
+        self.assertEqual(sorted(values), sorted(['S', 'M', 'L']))
+
+        # Two properties, one variation
+        p2 = Property.objects.get(event=e, name='Color')
+        i.properties.add(p2)
+        iv.values.add(PropertyValue.objects.get(prop=p2, value='black'))
+        v = i.get_all_variations()
+        self.assertIs(type(v), list)
+        self.assertEqual(len(v), 6)
+        values = []
+        num_variations = 0
+        for var in v:
+            if type(var) == ItemVariation:
+                self.assertEqual(iv.pk, var.pk)
+                values.append(sorted([ivv.value for ivv in iv.values.all()]))
+                self.assertEqual(sorted([ivv.value for ivv in iv.values.all()]), sorted(['S', 'black']))
+                num_variations += 1
+            elif type(var) == tuple:
+                values.append(sorted([pv.value for pv in var]))
+        self.assertEqual(sorted(values), sorted([
+            ['S', 'black'],
+            ['S', 'blue'],
+            ['M', 'black'],
+            ['M', 'blue'],
+            ['L', 'black'],
+            ['L', 'blue'],
+        ]))
+        self.assertEqual(num_variations, 1)