Add natural keys to the document type model

apps/documents/models.py

@@ -32,7 +32,8 @@ from converter.literals import (DEFAULT_ZOOM_LEVEL, DEFAULT_ROTATION,
 from .conf.settings import (CHECKSUM_FUNCTION, UUID_FUNCTION,
     STORAGE_BACKEND, DISPLAY_SIZE, CACHE_PATH,
     ZOOM_MAX_LEVEL, ZOOM_MIN_LEVEL)
-from .managers import DocumentPageTransformationManager, RecentDocumentManager
+from .managers import (DocumentPageTransformationManager, RecentDocumentManager,
+    DocumentTypeManager)
 from .utils import document_save_to_temp_dir
 from .literals import (RELEASE_LEVEL_FINAL, RELEASE_LEVEL_CHOICES,
     VERSION_UPDATE_MAJOR, VERSION_UPDATE_MINOR, VERSION_UPDATE_MICRO)
@@ -60,9 +61,14 @@ class DocumentType(models.Model):
     """
     name = models.CharField(max_length=32, verbose_name=_(u'name'), unique=True)
 
+    objects = DocumentTypeManager()
+
     def __unicode__(self):
         return self.name
 
+   def natural_key(self):
+        return (self.name,)
+
     class Meta:
         verbose_name = _(u'document type')
         verbose_name_plural = _(u'documents types')