fix BUG-25 by using ORM not db calls direct, could not see why they worked in DEV but not PROD with NO logs - only assume sqlachemy2 doesnt like the engine execute code I used instead

BUGs

@@ -1,6 +1,6 @@
 ### fix to get this working with bs 5...
 
-#### BUGS (next-25)
+#### BUGS (next-26)
 BUG-21: parent series now showing all books (thomas covenant series)
 
 ### DB/back-end

main.py

@@ -774,13 +774,9 @@ def stats():
 def rem_books_from_loan(id):
     for field in request.form:
         rem_id=int(re.findall( '\d+', field )[0])
-        try:
-            with db.engine.connect() as conn:
-                conn.exec_driver_sql( "delete from book_loan_link where book_id = {} and loan_id = {}".format( rem_id, id ))
+        bll = Book_Loan_Link.query.filter(Book_Loan_Link.loan_id==id, Book_Loan_Link.book_id == rem_id ).one()
+        db.session.delete(bll)
         db.session.commit()
-        except SQLAlchemyError as e:
-            st.SetAlert("danger")
-            st.SetMessage("Failed to remove books from loan! -- {}".format( e.orig ))
         return jsonify(success=True)
 
 @app.route("/add_books_to_loan/<id>", methods=["POST"])
@@ -788,13 +784,9 @@ def rem_books_from_loan(id):
 def add_books_to_loan(id):
     for field in request.form:
         add_id=int(re.findall( '\d+', field )[0])
-        try:
-            with db.engine.connect() as conn:
-                conn.exec_driver_sql( "insert into book_loan_link (book_id, loan_id) values ( {}, {} )".format( add_id, id ))
+        bll = Book_Loan_Link( loan_id=id, book_id=add_id )
+        db.session.add(bll)
         db.session.commit()
-        except SQLAlchemyError as e:
-            st.SetAlert("danger")
-            st.SetMessage("Failed to add books to loan! -- {}".format( e.orig ))
     return jsonify(success=True)
 
 @app.route("/rem_parent_books_from_series/<pid>", methods=["POST"])