cannot update row value for integer column in postgresql table - postgresql

Question

This is the dummy function I wrote to update the counter.
def updateTable(tableName, visitorId, dtWithZone):
db_uri = app.config["SQLALCHEMY_DATABASE_URI"]
engine = create_engine(db_uri, connect_args={"options": "-c timezone={}".format(dtWithZone.timetz().tzinfo.zone)})
# create session
Session = sessionmaker()
Session.configure(bind=engine)
session = Session()
meta = MetaData(engine, reflect=True)
table = meta.tables[tableName]
print dir(table)
# update row to database
row = session.query(table).filter(
table.c.visitorId == visitorId).first()
print 'original:', row.count
row.count = row.count + 1
print "updated {}".format(row.count)
session.commit()
conn.close()
but when it reaches the line row.count = row.count + 1 it throws error:
AttributeError: can't set attribute
this is the table
\d visitorinfo;
Table "public.visitorinfo"
Column | Type | Modifiers
--------------+--------------------------+-----------
platform | character varying(15) |
browser | character varying(10) |
visitorId | character varying(10) | not null
language | character varying(10) |
version | character varying(20) |
cl_lat | double precision |
cl_lng | double precision |
count | integer |
ip | character varying(20) |
visitor_time | timestamp with time zone |
Indexes:
"visitorinfo_pkey" PRIMARY KEY, btree ("visitorId")
what am I doing wrong ?why is it saying cannot set attribute?
part of updated code:
# update row to database
row = session.query(table).filter(
table.c.visitorId == visitorId).first()
print 'original:', row.count
val = row.count
row.count = val + 1
print "updated {}".format(row.count)

Answer 1

use an update query:
UPDATE public.visitorinfo SET counter = counter + 1 WHERE visitorId = 'VisitorID'
Make sure that last 'VisitorID' is filled from your application