Merge pull request #34 from yunojuno/issue-33

Fix issue #33 - null VersionField breaks ORM

CREDITS

@@ -20,6 +20,7 @@ The project has received contributions from (in alphabetical order):
 * Raphaël Barrois <raphael.barrois+semver@polytechnique.org> (https://github.com/rbarrois)
 * Michael Hrivnak <mhrivnak@hrivnak.org> (https://github.com/mhrivnak)
 * Rick Eyre <rick.eyre@outlook.com> (https://github.com/rickeyre)
+* Hugo Rodger-Brown <hugo@yunojuno.com> (https://github.com/yunojuno)
 
 
 Contributor license agreement

semantic_version/django_fields.py

@@ -18,7 +18,7 @@ class BaseSemVerField(models.CharField):
         super(BaseSemVerField, self).__init__(*args, **kwargs)
 
     def get_prep_value(self, obj):
-        return str(obj)
+        return None if obj is None else str(obj)
 
     def get_db_prep_value(self, value, connection, prepared=False):
         if not prepared:

tests/test_django.py

@@ -30,6 +30,13 @@ if django_loaded and django.VERSION < (1, 7):  # pragma: no cover
     except ImportError:
         pass
 
+# the refresh_from_db method only came in with 1.8, so in order to make this
+# work will all supported versions we have our own function.
+def save_and_refresh(obj):
+    """Saves an object, and refreshes from the database."""
+    obj.save()
+    obj = obj.__class__.objects.get(id=obj.id)
+
 
 @unittest.skipIf(not django_loaded, "Django not installed")
 class DjangoFieldTestCase(unittest.TestCase):
@@ -48,6 +55,38 @@ class DjangoFieldTestCase(unittest.TestCase):
 
         obj.full_clean()
 
+    def test_version_save(self):
+        """Test saving object with a VersionField."""
+        # first test with a null value
+        obj = models.PartialVersionModel()
+        self.assertIsNone(obj.id)
+        self.assertIsNone(obj.optional)
+        save_and_refresh(obj)
+        self.assertIsNotNone(obj.id)
+        self.assertIsNone(obj.optional_spec)
+
+        # now set to something that is not null
+        spec = semantic_version.Spec('==0,!=0.2')
+        obj.optional_spec = spec
+        save_and_refresh(obj)
+        self.assertEqual(obj.optional_spec, spec)
+
+    def test_spec_save(self):
+        """Test saving object with a SpecField."""
+        # first test with a null value
+        obj = models.PartialVersionModel()
+        self.assertIsNone(obj.id)
+        self.assertIsNone(obj.optional_spec)
+        save_and_refresh(obj)
+        self.assertIsNotNone(obj.id)
+        self.assertIsNone(obj.optional_spec)
+
+        # now set to something that is not null
+        spec = semantic_version.Spec('==0,!=0.2')
+        obj.optional_spec = spec
+        save_and_refresh(obj)
+        self.assertEqual(obj.optional_spec, spec)
+
     def test_partial_spec(self):
         obj = models.VersionModel(version='0.1.1', spec='==0,!=0.2')
         self.assertEqual(semantic_version.Version('0.1.1'), obj.version)