Improve Operation numbering in accounting

accounting/migrations/0012_auto_20160720_1847.py

@@ -0,0 +1,28 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('accounting', '0011_auto_20160718_1805'),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name='operation',
+            options={'ordering': ['-number']},
+        ),
+        migrations.AddField(
+            model_name='operation',
+            name='number',
+            field=models.IntegerField(default=1, verbose_name='number'),
+            preserve_default=False,
+        ),
+        migrations.AlterUniqueTogether(
+            name='operation',
+            unique_together=set([('number', 'journal')]),
+        ),
+    ]