Hai demirel,

     Please specify a header file,

                    from datetime import datetime

     First create a two datetime field in py file,

ex:

                    start_work = fields.Datetime(string="Start work")

                    end_work = fields.Datetime(string="End work")

                    work_hours=fields.Float(string="Total Working Hours",compute='sal_cal',store=True)

then create a compute function name as sal_cal

                    @api.depends('start_work','end_work')

                    def sal_cal(self):

                        t1= datetime.strptime(self.start_work, '%Y-%m-%d %H:%M:%S')

                        t2= datetime.strptime(self.end_work, '%Y-%m-%d %H:%M:%S')

                        s= datetime.strptime(str(t2.time()),'%H:%M:%S') - datetime.strptime(str(t1.time()),'%H:%M:%S')

In this above code is working perfectly to me.please check it now and let me know if any issue are occured

use this for ref.... surely it will heelp you..

from datetime import datetime
d1='2014-11-15'
d2='2013-11-15'
d1 = datetime.strptime(d1, "%Y-%m-%d")
d2 = datetime.strptime(d2, "%Y-%m-%d")
print abs((d2 - d1).days)/(12*30)
print datetime.now().date()

i want to find day with time difference...