Add sales channels (#1103)

- [x] Data model
- [x] Enforce constraint
- [x] Filter order list
- [x] Set channel on created order
- [x] Products API
- [x] Order API
- [x] Tests
- [x] Filter reports
- [x] Resellers
- [ ] deploy plugins
  - [ ] posbackend
  - [ ] resellers
  - [ ] reports
- [x] Ticketlayouts
- [x] Support in pretixPOS

src/tests/api/test_items.py

@@ -212,6 +212,7 @@ TEST_ITEM_RES = {
     "name": {"en": "Budget Ticket"},
     "internal_name": None,
     "default_price": "23.00",
+    "sales_channels": ["web"],
     "category": None,
     "active": True,
     "description": None,
@@ -352,6 +353,7 @@ def test_item_create(token_client, organizer, event, item, category, taxrule):
                 "en": "Ticket"
             },
             "active": True,
+            "sales_channels": ["web", "pretixpos"],
             "description": None,
             "default_price": "23.00",
             "free_price": False,
@@ -373,6 +375,7 @@ def test_item_create(token_client, organizer, event, item, category, taxrule):
         format='json'
     )
     assert resp.status_code == 201
+    assert Item.objects.get(pk=resp.data['id']).sales_channels == ["web", "pretixpos"]
 
 
 @pytest.mark.django_db