minor refactoring and fixed default value of VersionField

Author: saxix

concurrency/core.py

@@ -10,6 +10,10 @@ class RecordModifiedError(DatabaseError):
     pass
 
 
+class InconsistencyError(DatabaseError):
+    pass
+
+
 def apply_concurrency_check(model, fieldname, versionclass):
     """
     Apply concurrency management to existing Models.
@@ -42,20 +46,20 @@ def concurrency_check(model_instance, force_insert=False, force_update=False, us
 
 
 def _select_lock(model_instance, version_value=None):
+    version_field = model_instance.RevisionMetaInfo.field
+    value = getattr(model_instance, version_field.name)
+    is_versioned = value != version_field.get_default()
+
     if model_instance.pk is not None:
-        version_field = model_instance.RevisionMetaInfo.field
         kwargs = {'pk': model_instance.pk,
                   version_field.name: version_value or getattr(model_instance, version_field.name)}
         alias = router.db_for_write(model_instance)
         NOWAIT = connections[alias].features.has_select_for_update_nowait
         entry = model_instance.__class__.objects.select_for_update(nowait=NOWAIT).filter(**kwargs)
         if not entry:
-            value = getattr(model_instance, version_field.name)
-            if value != version_field.get_default():
-                raise RecordModifiedError(_('Version field is set (%s) but record has `pk`.' % value))
-            elif value == version_field.get_default():
-                return
             raise RecordModifiedError(_('Record has been modified'))
+    elif is_versioned:
+        raise InconsistencyError(_('Version field is set (%s) but record has `pk`.' % value))
 
 
 def _wrap_save(func):

concurrency/fields.py

@@ -24,7 +24,8 @@ def __init__(self, **kwargs):
         help_text = kwargs.get('help_text', _('record revision number'))
 
         super(VersionField, self).__init__(verbose_name, name, editable=True,
-                                           help_text=help_text, null=False, blank=False, default=1,
+                                           help_text=help_text, null=False, blank=False,
+                                           default=0,
                                            db_tablespace=db_tablespace, db_column=db_column)
 
     def get_default(self):
@@ -61,7 +62,7 @@ def get_internal_type(self):
         return "BigIntegerField"
 
     def pre_save(self, model_instance, add):
-        old_value = getattr(model_instance, self.attname)
+        old_value = getattr(model_instance, self.attname) or 0
         value = max(old_value + 1, (int(time.time() * 1000000) - OFFSET))
         setattr(model_instance, self.attname, value)
         return value
@@ -78,7 +79,7 @@ def get_internal_type(self):
         return "BigIntegerField"
 
     def pre_save(self, model_instance, add):
-        value = getattr(model_instance, self.attname) + 1
+        value = (getattr(model_instance, self.attname) or 0) + 1
         setattr(model_instance, self.attname, value)
         return value
 
@@ -127,6 +128,17 @@ def pre_save(self, model_instance, add):
 #             return None
 #         return time.strftime('%Y%m%d%H%M%S', value.timetuple())
 
+try:
+    from django_any import any_field
+    import random
+    from django.db.models.fields import Field, BigIntegerField
+    any_field.register(IntegerVersionField,
+                       lambda x, **kwargs: random.randint(1, BigIntegerField.MAX_BIGINT))
+    any_field.register(AutoIncVersionField,
+                       lambda x, **kwargs: random.randint(1, BigIntegerField.MAX_BIGINT))
+
+except ImportError as e:
+    pass
 
 try:
     from south.modelsinspector import add_introspection_rules

concurrency/tests/all.py

@@ -46,7 +46,7 @@ def _get_REVISION_NUMBER(obj):
 
     def _check_save(self, obj):
         obj.save()
-        assert obj.pk # sanity check
+        assert obj.pk is not None # sanity check
 
     def _get_form_data(self, **kwargs):
         data = {}
@@ -299,7 +299,7 @@ def _get_target(self):
 
     def _check_save(self, obj):
         obj.save()
-        assert obj.pk # sanity check
+        assert obj.pk is not None # sanity check
         self.assertTrue(obj.version)
 
     def _get_form_data(self, **kwargs):

concurrency/utils.py

@@ -48,7 +48,7 @@ def test_concurrency_conflict(self):
         v2 = get_revision_of_object(target_copy)
         assert v1 == v2, "got same row with different version (%s/%s)" % (v1, v2)
         target.save()
-        assert target.pk
+        assert target.pk is not None # sanity check
         self.assertRaises(RecordModifiedError, target_copy.save)
 
     def test_concurrency_safety(self):