Can anybody help me to write a salary rule which happens very often (i.e bonus).

But here we will give amount and from date , to date (with the help of one2many field in conract) that should be deducted from employee salary if the payroll is running in between the from dat and to date or else "0".

Created one2many field for amount ,start date ,end date and trying to pull the amount information in salary rule as above but can't.