added error handling if row exists in db for BookConnector

src/database/connectors/BookConnector.py

 from ..Connector import Connector
 from ..models.Book import Book
-
+from sqlalchemy.exc import IntegrityError
+import logging
 
 class BookConnector(Connector):
     def save_book(self, item):
@@ -10,5 +11,13 @@ class BookConnector(Connector):
         book.update(item)
         book.image_path = item['images'][0]['path']
 
-        session.add(book)
-        session.commit()
+        try:
+            session.add(book)
\ No newline at end of file
+            session.commit()
+        except IntegrityError:
+            logging.debug('Duplicate exist')
+            session.rollback()
+            session.query(Book).filter(Book.upc == book.upc).update({k:v for k, v in book.__dict__.items() if k in book.__table__.columns.keys()})
+            session.commit()
+
+