From fce57b2e1ce16529ab1d07353ee14b6ab761aa56 Mon Sep 17 00:00:00 2001
From: Arnaud Fabre <arnaud.fabre@camobscura.fr>
Date: Wed, 1 Jul 2015 12:26:12 +0200
Subject: [PATCH] utils

---
 core/utils.py | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 core/utils.py

diff --git a/core/utils.py b/core/utils.py
new file mode 100644
index 0000000..6275dd3
--- /dev/null
+++ b/core/utils.py
@@ -0,0 +1,50 @@
+# coding: utf-8
+
+# This file is part of memopol.
+#
+# memopol is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of
+# the License, or any later version.
+#
+# memopol is distributed in the hope that it will
+# be useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU General Affero Public
+# License along with django-representatives.
+# If not, see <http://www.gnu.org/licenses/>.
+#
+# Copyright (C) 2015 Arnaud Fabre <af@laquadrature.net>
+from __future__ import absolute_import
+
+from django.core.exceptions import ObjectDoesNotExist
+
+def create_child_instance_from_parent(child_cls, parent_instance):
+    parent_cls = parent_instance.__class__
+    field = child_cls._meta.get_ancestor_link(parent_cls).column
+
+    # We could specify a parent_identifier which is a unique field in
+    # the parent class that link child to parent
+    if hasattr(child_cls, 'parent_identifier'):
+        try:
+            child_instance = child_cls.objects.get(
+                **{child_cls.child_parent_identifier:
+                   getattr(parent_instance, child_cls.parent_identifier)}
+            )
+            setattr(child_instance, field, parent_instance.pk)
+        except ObjectDoesNotExist:
+            child_instance = child_cls(**{
+                field: parent_instance.pk,
+                child_cls.child_parent_identifier:
+                getattr(parent_instance, child_cls.parent_identifier)
+            })
+    else:
+        child_instance = child_cls(**{
+            field: parent_instance.pk
+        })
+        
+    child_instance.__dict__.update(parent_instance.__dict__)
+    child_instance.save()
+    return child_instance
-- 
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