Migration file to add unique constraint on user_to_service.

migrations/versions/0024_uix_user_to_service.py

@@ -0,0 +1,26 @@
+"""empty message
+
+Revision ID: 0024_uix_user_to_service
+Revises: 0023_drop_token
+Create Date: 2016-02-25 11:15:06.088508
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '0024_uix_user_to_service'
+down_revision = '0023_drop_token'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    ### commands auto generated by Alembic - please adjust! ###
+    op.create_unique_constraint('uix_user_to_service', 'user_to_service', ['user_id', 'service_id'])
+    ### end Alembic commands ###
+
+
+def downgrade():
+    ### commands auto generated by Alembic - please adjust! ###
+    op.drop_constraint('uix_user_to_service', 'user_to_service', type_='unique')
+    ### end Alembic commands ###