handle reverse foreign key serialization

opal/models.py

@@ -174,7 +174,11 @@ def _get_field_title(cls, name):
     @classmethod
     def _get_field_default(cls, name):
         field = cls._get_field(name)
-        default = field.get_default()
+
+        if isinstance(field, models.ManyToOneRel):
+            default = []
+        else:
+            default = field.get_default()
 
         # for blank fields the result is a blank string, lets just remove that
         if default == '':

opal/tests/models.py

@@ -73,7 +73,9 @@ class HouseOwner(models.PatientSubrecord):
 
 class House(dmodels.Model):
     address = dmodels.CharField(max_length=200)
-    house_owner = dmodels.ForeignKey(HouseOwner, null=True, blank=True, on_delete=dmodels.CASCADE)
+    house_owner = dmodels.ForeignKey(
+        HouseOwner, null=True, blank=True, on_delete=dmodels.CASCADE
+    )
 
 
 class Dog(lookuplists.LookupList):

opal/tests/test_models.py

@@ -3,7 +3,7 @@
 """
 import os
 import datetime
-from mock import patch, MagicMock
+from mock import patch
 
 from django.conf import settings
 from django.utils import timezone
@@ -428,8 +428,8 @@ def test_get_title_over_many_to_many(self):
         self.assertEqual(hats, "Hats")
 
     def test_get_title_over_reverse_foreign_key(self):
-        hats = HouseOwner._get_field_title("house")
-        self.assertEqual(hats, "Houses")
+        houses = HouseOwner._get_field_title("house")
+        self.assertEqual(houses, "Houses")
 
     def test_verbose_name(self):
         only_words = FamousLastWords._get_field_title("words")
@@ -463,6 +463,10 @@ def test_get_defaults_from_free_text_and_foreign_key(self):
     def test_get_defaults_from_free_text_and_foreign_key_lambda(self):
         self.assertEqual("spaniel", HoundOwner._get_field_default("dog"))
 
+    def test_get_defaults_from_reverse_foreign_key(self):
+        houses = HouseOwner._get_field_default("house")
+        self.assertEqual([], houses)
+
     def test_get_defaults_from_ftfk_when_there_are_no_defaults(self):
         self.assertEqual(None, Colour._get_field_default("name"))
 
@@ -860,4 +864,4 @@ def test_str(self):
 class UserProfileTestCase(OpalTestCase):
     def test_create(self):
         user = User.objects.create()
-        self.assertTrue(bool(user.profile))
+        self.assertTrue(bool(user.profile))