Remove use of storage wrappers

Use a dynamic subclass instead that always deconstructs to a fake
subclass with a __eq__ method that always returns True. This should
trick makemigrations into never creating a new migrations for
changes to the storage class or the arguments.

Signed-off-by: Roberto Rosario <Roberto.Rosario@mayan-edms.com>

mayan/apps/documents/migrations/0051_auto_20181229_0745.py

@@ -1,9 +1,9 @@
 # -*- coding: utf-8 -*-
-# Generated by Django 1.11.16 on 2018-12-28 04:22
+# Generated by Django 1.11.16 on 2018-12-29 07:45
 from __future__ import unicode_literals
 
 from django.db import migrations, models
-import mayan.apps.documents.storages
+import mayan.apps.common.classes
 import mayan.apps.documents.utils
 
 
@@ -17,6 +17,6 @@ class Migration(migrations.Migration):
         migrations.AlterField(
             model_name='documentversion',
             name='file',
-            field=models.FileField(storage=mayan.apps.documents.storages.storage_documentversion_wrapper, upload_to=mayan.apps.documents.utils.document_uuid_function, verbose_name='File'),
+            field=models.FileField(storage=mayan.apps.common.classes.FakeStorageSubclass(), upload_to=mayan.apps.documents.utils.document_uuid_function, verbose_name='File'),
         ),
     ]

mayan/apps/documents/models/document_version_models.py

@@ -21,7 +21,7 @@ from ..literals import DOCUMENT_IMAGES_CACHE_NAME
 from ..managers import DocumentVersionManager
 from ..settings import setting_fix_orientation
 from ..signals import post_document_created, post_version_upload
-from ..storages import storage_documentversion_wrapper
+from ..storages import storage_documentversion
 from ..utils import document_hash_function, document_uuid_function
 
 from .document_models import Document
@@ -67,7 +67,7 @@ class DocumentVersion(models.Model):
 
     # File related fields
     file = models.FileField(
-        storage=storage_documentversion_wrapper, upload_to=document_uuid_function,
+        storage=storage_documentversion, upload_to=document_uuid_function,
         verbose_name=_('File')
     )
     mimetype = models.CharField(
@@ -137,7 +137,7 @@ class DocumentVersion(models.Model):
         be in the document storage. This is a diagnostic flag to help users
         detect if the storage has desynchronized (ie: Amazon's S3).
         """
-        return self.file.storage().exists(self.file.name)
+        return self.file.storage.exists(self.file.name)
 
     def fix_orientation(self):
         for page in self.pages.all():
@@ -329,7 +329,7 @@ class DocumentVersion(models.Model):
     @property
     def size(self):
         if self.exists():
-            return self.file.storage().size(self.file.name)
+            return self.file.storage.size(self.file.name)
         else:
             return None
 

mayan/apps/documents/storages.py

@@ -2,20 +2,18 @@ from __future__ import unicode_literals
 
 from django.utils.module_loading import import_string
 
+from mayan.apps.common.utils import get_storage_subclass
+
 from .settings import (
     setting_documentimagecache_storage,
     setting_documentimagecache_storage_arguments, setting_storage_backend,
     setting_storage_backend_arguments
 )
 
-storage_documentversion = import_string(
+storage_documentversion = get_storage_subclass(
     dotted_path=setting_storage_backend.value
 )(**setting_storage_backend_arguments.value)
 
 storage_documentimagecache = import_string(
     dotted_path=setting_documentimagecache_storage.value
 )(**setting_documentimagecache_storage_arguments.value)
-
-
-def storage_documentversion_wrapper():
-    return storage_documentversion