various improvements

sections/model.py

@@ -1,6 +1,6 @@
 from sqlalchemy import Column, Integer, String, Boolean, DateTime, Text, ForeignKey
 from sqlalchemy.orm import relationship
-
+from sqlalchemy.exc import IntegrityError, InvalidRequestError
 from datetime import datetime
 from src.database import Base,db_session
 from marshmallow import Schema, fields, post_load
@@ -82,7 +82,11 @@ class Section(Base):
         if s is None:
             s=Section(fname)
             db_session.add(s)
-            db_session.commit()
+            try:
+                db_session.commit()
+            except (IntegrityError, InvalidRequestError),e:
+                db_session.rollback()
+                clogger.error(e)
         s.foreign_name=fname
         db_session.add(s)
         db_session.commit()