TypeError'>: unsupported operand type(s) for *: 'NoneType' and 'float' [on hold]

today = dt.date.today()
          first = today.replace(day=1)
          lastMonth = first - dt.timedelta(days=1)
          previous_month = int(lastMonth.strftime("%m"))


          # Calculating sundays
          day = dt.date(today.year, previous_month, 1)
          single_day = dt.timedelta(days=1)
          sundays = 0
          while day.month == previous_month:
              if day.weekday() == 6:
                  sundays += 1
              day += single_day


          # calculating days from previous month
          year = today.year
          day = previous_month
          total_days = monthrange(year, day)
          total_days_1 = int(total_days[1])
          current_days = total_days_1 - sundays
          total_month_hours = current_days * 8

          # calculate worked _hours for previous month:
          s = (
              """select sum(worked_hours) from hr_attendance where employee_id=%s and name >= date_trunc('month', current_date - interval '1' month)and name < date_trunc('month', current_date)""" % (
                  obj.employee_id.id))
          cr.execute(s)
          l = cr.fetchone()
          total_worked_hours = l[0]
          print total_worked_hours
          # select wages for employee given:
          if total_worked_hours != None and total_worked_hours >0.00 :
           s1 = (
              """select salary from  hr_contract where employee_id=%s""" % (
                  obj.employee_id.id))
           cr.execute(s1)
           l1 = cr.fetchone()
           per_hour_salary = l1[0]

           if total_month_hours > total_worked_hours:
              overtime = (total_month_hours) - (total_worked_hours)
              incentive = overtime * (per_hour_salary * 1.5)
              total_wage = (total_worked_hours )* (per_hour_salary)
              total_sal = (total_wage) + (incentive)
              print obj.employee_id.id
              print total_sal
              cr.execute(""" update hr_contract set wage=%s where employee_id=%s""" % (
                  total_sal, obj.employee_id.id))
           else:

              if total_worked_hours != None and total_worked_hours > 0.00:
                 perhourwage = ((total_worked_hours) * (per_hour_salary))
                 total_sal = perhourwage
                 res[obj.id] = total_sal
                 cr.execute(""" update hr_contract set wage=%s where employee_id=%s""" % (
                   total_sal, obj.employee_id.id))

I don't know where the error is. I have set the condition to not null even though the error comes.

I can't able to find where the error comes. I have also given the non null value it shows the same error.

How can I solve this?

Help me with a solution.

Thanks.