Improve serialization migration for the models: Document, DocumentVersion, DocumentMetadata and DocumentTypeOCRSettings

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/documents/managers.py

@@ -20,7 +20,7 @@ class DocumentManager(models.Manager):
             stale_stub_document.delete(trash=False)
 
     def get_by_natural_key(self, uuid):
-        return self.get(uuid=uuid)
+        return self.model.passthrough.get(uuid=uuid)
 
     def get_queryset(self):
         return TrashCanQuerySet(
@@ -32,6 +32,19 @@ class DocumentManager(models.Manager):
             document.invalidate_cache()
 
 
+class DocumentVersionManager(models.Manager):
+    def get_by_natural_key(self, checksum, document_natural_key):
+        Document = apps.get_model(
+            app_label='documents', model_name='Document'
+        )
+        try:
+            document = Document.objects.get_by_natural_key(document_natural_key)
+        except Document.DoesNotExist:
+            raise self.model.DoesNotExist
+
+        return document.versions.get(checksum=checksum)
+
+
 class DocumentTypeManager(models.Manager):
     def check_delete_periods(self):
         logger.info('Executing')

mayan/apps/documents/models.py

@@ -33,8 +33,9 @@ from .events import (
 )
 from .literals import DEFAULT_DELETE_PERIOD, DEFAULT_DELETE_TIME_UNIT
 from .managers import (
-    DocumentManager, DocumentTypeManager, DuplicatedDocumentManager,
-    PassthroughManager, RecentDocumentManager, TrashCanManager
+    DocumentManager, DocumentVersionManager, DocumentTypeManager,
+    DuplicatedDocumentManager, PassthroughManager, RecentDocumentManager,
+    TrashCanManager
 )
 from .permissions import permission_document_view
 from .settings import (
@@ -415,6 +416,8 @@ class DocumentVersion(models.Model):
         verbose_name = _('Document version')
         verbose_name_plural = _('Document version')
 
+    objects = DocumentVersionManager()
+
     def __str__(self):
         return self.get_rendered_string()
 
@@ -505,6 +508,10 @@ class DocumentVersion(models.Model):
             context=Context({'instance': self})
         )
 
+    def natural_key(self):
+        return (self.checksum,) + self.document.natural_key()
+    natural_key.dependencies = ['documents.Document']
+
     def invalidate_cache(self):
         storage_documentimagecache.delete(self.cache_filename)
         for page in self.pages.all():