I'm a beginner in python.

Please i am trying to define in my new module for manage Human resource posting, a field fonction named "date_to" which have to display the end date of the employee posting. I use two step to do this: fonction and field definition

Here is the fonction code

#Automatic determination of field date_to

def compute_date_to(self, date_from, date_to): # I define date_from and date_to field.datetime in the object hr.posting
    """Returns a end date for hr.posting ."""

    DATETIME_FORMAT = "%Y-%m-%d %H:%M:%S"
    from_dt = datetime.datetime.strptime(date_from, DATETIME_FORMAT)
    to_dat = datetime.datetime.strptime(date_to, DATETIME_FORMAT)      
    to_dat = from_dat + timedelta(days=1826)   # Here I'm fixing the timedelta days(1826 days = 5years for me) between date_from and date_to
    return to_dat

Here is the field code

'date_to': fields.function(compute_date_to, string='Date Departure', type='datetime', readonly=True, store=True), The module is installed correctly but when i try to save one posting i have this error

Client Traceback (most recent call last): File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/addons/web/http.py", line 204, in dispatch response["result"] = method(self, *self.params) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/addons/web/controllers/main.py", line 1130, in call_kw return self._call_kw(req, model, method, args, kwargs) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/addons/web/controllers/main.py", line 1122, in _call_kw return getattr(req.session.model(model), method)(args, **kwargs) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/addons/web/session.py", line 42, in proxy result = self.proxy.execute_kw(self.session._db, self.session._uid, self.session._password, self.model, method, args, kw) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/addons/web/session.py", line 30, in proxy_method result = self.session.send(self.service_name, method, *args) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/addons/web/session.py", line 103, in send raise xmlrpclib.Fault(openerp.tools.ustr(e), formatted_info)

Server Traceback (most recent call last): File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/addons/web/session.py", line 89, in send return openerp.netsvc.dispatch_rpc(service_name, method, args) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/netsvc.py", line 292, in dispatch_rpc result = ExportService.getService(service_name).dispatch(method, params) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/service/web_services.py", line 626, in dispatch res = fn(db, uid, params) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/osv/osv.py", line 188, in execute_kw return self.execute(db, uid, obj, method, *args, *kw or {}) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/osv/osv.py", line 131, in wrapper return f(self, dbname, args, *kwargs) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/osv/osv.py", line 197, in execute res = self.execute_cr(cr, uid, obj, method, args, *kw) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/osv/osv.py", line 185, in execute_cr return getattr(object, method)(cr, uid, args, *kw) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/addons/mail/mail_thread.py", line 242, in create thread_id = super(mail_thread, self).create(cr, uid, values, context=context) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/osv/orm.py", line 4478, in create self.pool.get(object)._store_set_values(cr, user, ids, fields2, context) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/osv/orm.py", line 4627, in _store_set_values result = self._columns[f].get(cr, self, ids, f, SUPERUSER_ID, context=context) File "/home/benos/Public/latest/openerp-7.0-20130723-231040/openerp/osv/fields.py", line 1133, in get result = self._fnct(obj, cr, uid, ids, name, self._arg, context) TypeError: compute_date_to() takes exactly 3 arguments (7 given)

i know i choose the wrong way help me.