+ # default values for created and updated are only there to keep evolution
+ # from failing.
+
+ created = models.DateTimeField(auto_now_add=True, default=datetime.datetime.now())
+ updated = models.DateTimeField(auto_now=True, default=datetime.datetime.now())
+ enacted = models.DateTimeField(null=True, default=None)
+
+ class Meta:
+ abstract = True
+ app_label = "core"
+
+ def __init__(self, *args, **kwargs):
+ super(PlCoreBase, self).__init__(*args, **kwargs)
+ self.__initial = self._dict
+
+ @property
+ def diff(self):
+ d1 = self.__initial
+ d2 = self._dict
+ diffs = [(k, (v, d2[k])) for k, v in d1.items() if v != d2[k]]
+ return dict(diffs)
+
+ @property
+ def has_changed(self):
+ return bool(self.diff)
+
+ @property
+ def changed_fields(self):
+ return self.diff.keys()
+
+ def get_field_diff(self, field_name):
+ return self.diff.get(field_name, None)
+
+ def can_update(self, user):
+ if user.is_readonly:
+ return False
+ if user.is_admin:
+ return True
+ return False
+
+ def delete(self, *args, **kwds):
+ # so we have something to give the observer
+ pk = self.pk
+ model_dict = model_to_dict(self)
+ for (k,v) in model_dict.items():
+ # things like datetime are not JSON serializable
+ model_dict[k] = str(v)
+
+ super(PlCoreBase, self).delete(*args, **kwds)
+
+ # This is a no-op if observer_disabled is set
+ notify_observer(model=self, delete=True, pk=pk, model_dict=model_dict)
+
+ def save(self, *args, **kwargs):
+ super(PlCoreBase, self).save(*args, **kwargs)
+
+ # This is a no-op if observer_disabled is set
+ notify_observer()
+
+ self.__initial = self._dict
+
+ def save_by_user(self, user, *args, **kwds):
+ if self.can_update(user):
+ self.save(*args, **kwds)
+
+ def delete_by_user(self, user, *args, **kwds):
+ if self.can_update(user):
+ self.delete(*args, **kwds)
+
+ @property
+ def _dict(self):
+ return model_to_dict(self, fields=[field.name for field in
+ self._meta.fields])