Add unique constraint to sources table - label column

lemur/migrations/versions/6006c79b6011_.py

@@ -0,0 +1,21 @@
+"""Add unique constraint to label column on sources table
+
+Revision ID: 6006c79b6011
+Revises: 984178255c83
+Create Date: 2018-10-19 15:23:06.750510
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '6006c79b6011'
+down_revision = '984178255c83'
+
+from alembic import op
+
+
+def upgrade():
+    op.create_unique_constraint("uq_label", 'sources', ['label'])
+
+
+def downgrade():
+    op.drop_constraint("uq_label", 'sources', type_='unique')

lemur/sources/models.py

@@ -17,7 +17,7 @@ from sqlalchemy_utils import ArrowType
 class Source(db.Model):
     __tablename__ = 'sources'
     id = Column(Integer, primary_key=True)
-    label = Column(String(32))
+    label = Column(String(32), unique=True)
     options = Column(JSONType)
     description = Column(Text())
     plugin_name = Column(String(32))