Fix backup restore

This merge request fixes the backup restore system.

Note that it might not be backward compatible.

Fixes #492

beat/web/databases/models.py

@@ -301,6 +301,7 @@ class DatabaseProtocol(models.Model):
 
     def natural_key(self):
         return self.database.natural_key() + (self.name,)
+    natural_key.dependencies = ['databases.database']
 
     def fullname(self):
         if self.name != '':
@@ -394,6 +395,8 @@ class DatabaseSet(models.Model):
 
     def natural_key(self):
         return self.protocol.natural_key() + (self.name,) + self.template.natural_key()
+    natural_key.dependencies = ['databases.databaseprotocol',
+                                'databases.databasesettemplate']
 
     def fullname(self):
         if self.name != '':
@@ -437,15 +440,10 @@ class DatabaseSetTemplateOutput(models.Model):
 
 
 class DatabaseSetOutputManager(models.Manager):
-
-    def get_by_natural_key(self, database_name, database_version, protocol_name, name,
-                           template_name, output_name):
+    def get_by_natural_key(self, set_natural_key, output_name):
+        set_ = DatabaseSet.objects.get_by_natural_key(*set_natural_key)
         return self.get(
-            set__protocol__database__name=database_name,
-            set__protocol__database__version=database_version,
-            set__protocol__name=protocol_name,
-            set__name=name,
-            set__template__name=template_name,
+            set=set_,
             template__name=output_name,
         )
 
@@ -477,3 +475,5 @@ class DatabaseSetOutput(models.Model):
 
     def natural_key(self):
         return (self.set.natural_key(), self.template.name)
+    natural_key.dependencies = ['databases.databasesettemplateoutput',
+                                'databases.databaseset']