Hiii good people,

is it possible to calculate the value of a float field in the one2many field?

if can please tell me, my current code : 

parking_log_ids=fields.One2many('parking_log','parking_log_id',string='Log Parkir')

total_bill_id=fields.Integer(string='Total Tarif', compute='_compute_biaya_total')

@api.multi
    def _compute_biaya_total(self):
        self.total_bill_id = len(self.parking_log_ids) 


total_rate=fields.Float(string='Total Biaya Parkir')
@api.multi
    def action_close(self):
        bill_ = self.rate_id
        end_time_days = abs(fields.Datetime.from_string(fields.Datetime.now()) - fields.Datetime.from_string(self.start_time)).days
        end_time_seconds = abs(fields.Datetime.from_string(fields.Datetime.now()) - fields.Datetime.from_string(self.start_time)).seconds
        end_time_hours = end_time_days * 24.00 + end_time_seconds // 3600.00
        amount = bill_ + (end_time_hours - 0.5) * bill_ 
        

self.write({'total_rate':amount})


My code currently only counts many fields instead of values ​​that are in the field. 
what I want is to calculate the value in o2m(parking_log_ids) that is field 'total_rate' to 'total_bill_id'

I will appreciate all the answers, thank you very much