Add a new auto-slug field that is concurrency resistent

localized_fields/db_backend/base.py

@@ -5,6 +5,8 @@ from django.core.exceptions import ImproperlyConfigured
 from django.db.backends.postgresql.base import \
     DatabaseWrapper as Psycopg2DatabaseWrapper
 
+from ..fields import LocalizedField
+
 
 def _get_backend_base():
     """Gets the base class for the custom database back-end.
@@ -153,7 +155,22 @@ class SchemaEditor(_get_schema_editor_base()):
             *args, **kwargs
         )
 
-        self._update_hstore_constraints(model, old_field, new_field)
+        is_old_field_localized = isinstance(old_field, LocalizedField)
+        is_new_field_localized = isinstance(new_field, LocalizedField)
+
+        if is_old_field_localized or is_new_field_localized:
+            self._update_hstore_constraints(model, old_field, new_field)
+
+    def create_model(self, model):
+        """Ran when a new model is created."""
+
+        super().create_model(model)
+
+        for field in model._meta.local_fields:
+            if not isinstance(field, LocalizedField):
+                continue
+
+            self._update_hstore_constraints(model, field, field)
 
 
 class DatabaseWrapper(_get_backend_base()):

localized_fields/fields/localized_magicslug_field.py

@@ -59,6 +59,9 @@ class LocalizedMagicSlugField(LocalizedAutoSlugField):
                 continue
 
             slug = slugify(value, allow_unicode=True)
+            if instance.retries > 0:
+                slug += '-%d' % instance.retries
+
             slugs.set(lang_code, slug)
 
         setattr(instance, self.name, slugs)

localized_fields/models.py

@@ -1,4 +1,6 @@
 from django.db import models
+from django.db.utils import IntegrityError
+from django.db import transaction
 
 from .fields import LocalizedField
 from .localized_value import LocalizedValue
@@ -32,3 +34,30 @@ class LocalizedModel(models.Model):
                     value = LocalizedValue()
 
             setattr(self, field.name, value)
+
+    def save(self, *args, **kwargs):
+        """Saves this model instance to the database."""
+
+        if not hasattr(self, 'retries'):
+            self.retries = 0
+
+        error = None
+        with transaction.atomic():
+            try:
+                return super(LocalizedModel, self).save(*args, **kwargs)
+            except IntegrityError as ex:
+                # this is as retarded as it looks, there's no
+                # way we can put the retry logic inside the slug
+                # field class... we can also not only catch exceptions
+                # that apply to slug fields... so yea.. this is as
+                # retarded as it gets... i am sorry :(
+                if 'slug' not in str(ex):
+                    raise ex
+
+                error = ex
+
+        if self.retries >= 100:
+            raise error
+
+        self.retries += 1
+        return self.save()