LocalizedUniqueSlugField refactored

README.rst

@@ -194,11 +194,10 @@ Besides ``LocalizedField``, there's also:
           .. code-block:: python
 
               from localized_fields import (LocalizedModel,
-                                            AtomicSlugRetryMixin,
                                             LocalizedField,
                                             LocalizedUniqueSlugField)
 
-              class MyModel(AtomicSlugRetryMixin, LocalizedModel):
+              class MyModel(LocalizedModel):
                    title = LocalizedField()
                    slug = LocalizedUniqueSlugField(populate_from='title')
 

localized_fields/fields/localized_uniqueslug_field.py

@@ -1,18 +1,19 @@
 from datetime import datetime
 
 from django.conf import settings
+from django import forms
 from django.utils.text import slugify
-from django.core.exceptions import ImproperlyConfigured
+from django.db import transaction
+from django.db.utils import IntegrityError
+
 
 from ..util import get_language_codes
-from ..mixins import AtomicSlugRetryMixin
 from ..localized_value import LocalizedValue
-from .localized_autoslug_field import LocalizedAutoSlugField
+from .localized_field import LocalizedField
 
 
-class LocalizedUniqueSlugField(LocalizedAutoSlugField):
-    """Automatically provides slugs for a localized
-    field upon saving."
+class LocalizedUniqueSlugField(LocalizedField):
+    """Automatically provides slugs for a localized field upon saving."
 
     An improved version of :see:LocalizedAutoSlugField,
     which adds:
@@ -21,8 +22,6 @@ 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):
@@ -30,14 +29,11 @@ class LocalizedUniqueSlugField(LocalizedAutoSlugField):
 
         kwargs['uniqueness'] = kwargs.pop('uniqueness', get_language_codes())
 
-        super(LocalizedUniqueSlugField, self).__init__(
-            *args,
-            **kwargs
-        )
-
         self.populate_from = kwargs.pop('populate_from')
         self.include_time = kwargs.pop('include_time', False)
 
+        super().__init__(*args, **kwargs)
+
     def deconstruct(self):
         """Deconstructs the field into something the database
         can store."""
@@ -49,36 +45,88 @@ class LocalizedUniqueSlugField(LocalizedAutoSlugField):
         kwargs['include_time'] = self.include_time
         return name, path, args, kwargs
 
-    def pre_save(self, instance, add: bool):
-        """Ran just before the model is saved, allows us to built
-        the slug.
+    def formfield(self, **kwargs):
+        """Gets the form field associated with this field.
+
+        Because this is a slug field which is automatically
+        populated, it should be hidden from the form.
+        """
+
+        defaults = {
+            'form_class': forms.CharField,
+            'required': False
+        }
+
+        defaults.update(kwargs)
+
+        form_field = super().formfield(**defaults)
+        form_field.widget = forms.HiddenInput()
+
+        return form_field
+
+    def contribute_to_class(self, cls, name, *args, **kwargs):
+        """Hook that allow us to operate with model class. We overwrite save()
+        method to run retry logic.
+
+        Arguments:
+            cls:
+                Model class.
+
+            name:
+                Name of field in model.
+        """
+        # apparently in inheritance cases, contribute_to_class is called more
+        # than once, so we have to be careful not to overwrite the original
+        # save method.
+        if not hasattr(cls, '_orig_save'):
+            cls._orig_save = cls.save
+            max_retries = getattr(
+                settings,
+                'LOCALIZED_FIELDS_MAX_RETRIES',
+                100
+            )
+
+            def _new_save(instance, *args_, **kwargs_):
+                retries = 0
+                while True:
+                    with transaction.atomic():
+                        try:
+                            slugs = self.populate_slugs(instance, retries)
+                            setattr(instance, name, slugs)
+                            instance._orig_save(*args_, **kwargs_)
+                            break
+                        except IntegrityError as e:
+                            if retries >= max_retries:
+                                raise e
+                            # check to be sure a slug fight caused
+                            # the IntegrityError
+                            s_e = str(e)
+                            if name in s_e and 'unique' in s_e:
+                                retries += 1
+                            else:
+                                raise e
+
+            cls.save = _new_save
+        super().contribute_to_class(cls, name, *args, **kwargs)
+
+    def populate_slugs(self, instance, retries=0):
+        """Built the slug from populate_from field.
 
         Arguments:
             instance:
                 The model that is being saved.
 
-            add:
-                Indicates whether this is a new entry
-                to the database or an update.
+            retries:
+                The value of the current attempt.
 
         Returns:
             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()
-
+        populates_slugs = getattr(instance, self.populate_from, {})
         for lang_code, _ in settings.LANGUAGES:
-            value = self._get_populate_from_value(
-                instance,
-                self.populate_from,
-                lang_code
-            )
+
+            value = populates_slugs.get(lang_code)
 
             if not value:
                 continue
@@ -98,13 +146,11 @@ class LocalizedUniqueSlugField(LocalizedAutoSlugField):
             if self.include_time:
                 slug += '-%d' % datetime.now().microsecond
 
-            if instance.retries > 0:
+            if retries > 0:
                 # do not add another - if we already added time
                 if not self.include_time:
                     slug += '-'
-                slug += '%d' % instance.retries
+                slug += '%d' % retries
 
             slugs.set(lang_code, slug)
-
-        setattr(instance, self.name, slugs)
         return slugs

localized_fields/mixins.py

@@ -1,38 +1,17 @@
-from django.db import transaction
-from django.conf import settings
-from django.db.utils import IntegrityError
-
+from django.core.checks import Warning
 
 class AtomicSlugRetryMixin:
-    """Makes :see:LocalizedUniqueSlugField work by retrying upon
-    violation of the UNIQUE constraint."""
+    """A Mixin keeped for backwards compatibility"""
 
-    def save(self, *args, **kwargs):
-        """Saves this model instance to the database."""
-
-        max_retries = getattr(
-            settings,
-            'LOCALIZED_FIELDS_MAX_RETRIES',
-            100
+    @classmethod
+    def check(cls, **kwargs):
+        errors = super().check(**kwargs)
+        errors.append(
+            Warning(
+                'localized_fields.AtomicSlugRetryMixin is deprecated',
+                hint='There is no need to use '
+                     'localized_fields.AtomicSlugRetryMixin',
+                obj=cls
+            )
         )
-
-        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()
+        return errors

tests/fake_model.py

@@ -14,7 +14,7 @@ def define_fake_model(name='TestModel', fields=None):
 
     if fields:
         attributes.update(fields)
-    model = type(name, (AtomicSlugRetryMixin,LocalizedModel,), attributes)
+    model = type(name, (LocalizedModel,), attributes)
 
     return model