Ad a reference to the model

- used if 3rd party needs to record an ID for reconciliation purposes

migrations/versions/0040_add_reference.py

@@ -0,0 +1,24 @@
+"""empty message
+
+Revision ID: 0040_add_reference
+Revises: 0039_more_notification_states
+Create Date: 2016-03-11 09:15:57.900192
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '0040_add_reference'
+down_revision = '0039_more_notification_states'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    op.add_column('notifications', sa.Column('reference', sa.String(), nullable=True))
+    op.create_index(op.f('ix_notifications_reference'), 'notifications', ['reference'], unique=False)
+
+
+def downgrade():
+    op.drop_index(op.f('ix_notifications_reference'), table_name='notifications')
+    op.drop_column('notifications', 'reference')