Moved retry mechanism to mixin

Author: Photonios

localized_fields/__init__.py

@@ -2,8 +2,9 @@
 from .forms import LocalizedFieldForm, LocalizedFieldWidget
 from .fields import (LocalizedField, LocalizedBleachField,
                      LocalizedAutoSlugField, LocalizedUniqueSlugField)
-from .localized_value import LocalizedValue
+from .mixins import AtomicSlugRetryMixin
 from .models import LocalizedModel
+from .localized_value import LocalizedValue
 
 __all__ = [
     'get_language_codes',
@@ -14,5 +15,6 @@
     'LocalizedBleachField',
     'LocalizedFieldWidget',
     'LocalizedFieldForm',
-    'LocalizedModel'
+    'LocalizedModel',
+    'AtomicSlugRetryMixin'
 ]

localized_fields/db_backend/base.py

@@ -34,14 +34,14 @@ def _get_backend_base():
             '\'%s\' is not a valid database back-end.'
             ' The module does not define a DatabaseWrapper class.'
             ' Check the value of LOCALIZED_FIELDS_DB_BACKEND_BASE.'
-        ))
+        ) % base_class_name)
 
     if isinstance(base_class, Psycopg2DatabaseWrapper):
         raise ImproperlyConfigured((
             '\'%s\' is not a valid database back-end.'
             ' It does inherit from the PostgreSQL back-end.'
             ' Check the value of LOCALIZED_FIELDS_DB_BACKEND_BASE.'
-        ))
+        ) % base_class_name)
 
     return base_class
 

localized_fields/fields/localized_uniqueslug_field.py

@@ -1,9 +1,11 @@
 from django.conf import settings
 from django.utils.text import slugify
+from django.core.exceptions import ImproperlyConfigured
 
+from ..util import get_language_codes
+from ..mixins import AtomicSlugRetryMixin
 from ..localized_value import LocalizedValue
 from .localized_autoslug_field import LocalizedAutoSlugField
-from ..util import get_language_codes
 
 
 class LocalizedUniqueSlugField(LocalizedAutoSlugField):
@@ -17,6 +19,8 @@ class LocalizedUniqueSlugField(LocalizedAutoSlugField):
         - Improved performance
 
     When in doubt, use this over :see:LocalizedAutoSlugField.
+    Inherit from :see:AtomicSlugRetryMixin in your model to
+    make this field work properly.
     """
 
     def __init__(self, *args, **kwargs):
@@ -46,6 +50,12 @@ def pre_save(self, instance, add: bool):
             The localized slug that was generated.
         """
 
+        if not isinstance(instance, AtomicSlugRetryMixin):
+            raise ImproperlyConfigured((
+                'Model \'%s\' does not inherit from AtomicSlugRetryMixin. '
+                'Without this, the LocalizedUniqueSlugField will not work.'
+            ) % type(instance).__name__)
+
         slugs = LocalizedValue()
 
         for lang_code, _ in settings.LANGUAGES:

localized_fields/mixins.py

@@ -0,0 +1,38 @@
+from django.db import transaction
+from django.conf import settings
+from django.db.utils import IntegrityError
+
+
+class AtomicSlugRetryMixin:
+    """Makes :see:LocalizedUniqueSlugField work by retrying upon
+    violation of the UNIQUE constraint."""
+
+    def save(self, *args, **kwargs):
+        """Saves this model instance to the database."""
+
+        max_retries = getattr(
+            settings,
+            'LOCALIZED_FIELDS_MAX_RETRIES',
+            100
+        )
+
+        if not hasattr(self, 'retries'):
+            self.retries = 0
+
+        with transaction.atomic():
+            try:
+                return super().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
+
+                if self.retries >= max_retries:
+                    raise ex
+
+        self.retries += 1
+        return self.save()

localized_fields/models.py

@@ -34,33 +34,3 @@ def __init__(self, *args, **kwargs):
                     value = LocalizedValue()
 
             setattr(self, field.name, value)
-
-    def save(self, *args, **kwargs):
-        """Saves this model instance to the database."""
-
-        max_retries = getattr(
-            settings,
-            'LOCALIZED_FIELDS_MAX_RETRIES',
-            100
-        )
-
-        if not hasattr(self, 'retries'):
-            self.retries = 0
-
-        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
-
-                if self.retries >= max_retries:
-                    raise ex
-
-        self.retries += 1
-        return self.save()

tests/fake_model.py

@@ -2,7 +2,7 @@
 from django.db.migrations.executor import MigrationExecutor
 from django.contrib.postgres.operations import HStoreExtension
 
-from localized_fields import LocalizedModel
+from localized_fields import LocalizedModel, AtomicSlugRetryMixin
 
 
 def define_fake_model(name='TestModel', fields=None):
@@ -14,7 +14,7 @@ def define_fake_model(name='TestModel', fields=None):
 
     if fields:
         attributes.update(fields)
-    model = type(name, (LocalizedModel,), attributes)
+    model = type(name, (AtomicSlugRetryMixin,LocalizedModel,), attributes)
 
     return model