In my custom module i have two many2one fields ,the data in second many2one field should load dynamically depending upon the value selected in first many2one field ...So for this i called onchange method from first many2one field ,in this function i am setting the domain for second many2one field but i am not getting data with filtered records ????

sample.py

'commodity_name':fields.many2one('commodities.list','Commodity Name'),
'units':fields.many2one('units.list','Units')

def loadDataInSecondBox(self,cr,uid,ids,commodity_name)
    cond_val="Here in this variable i am getting particular id/value based on selected commodity name from database through some logic."
    domain = {'units': [('basic_unit_id', '=', cond_val)]}
    return {'domain': domain} 

   #res={'quantity':1000000000}
   #domain = {'units': [('basic_unit_id', '=', cond_val)]}
   #return {'value':res,'domain':domain,'warning':{'title':('Alert'),'message':('hello world,welcome')}}

sample_view.xml

<field name="commodity_name" on_change="loadDataInSecondBox(commodity_name)"/>
<field name="units" />

units.list in py file

class BasicUnitCreation(osv.osv):
    _name = "units.list"
    _description = "Basic Units Creation"
    _columns = {
        'name': fields.char('Unit Name', size=64, required=True),
        'basic_unit_id':fields.integer('Basic Unit Id',size=3,required=True),
        'conversion_value':fields.integer('Conversion Value',size=5,required=True),        
    }
BasicUnitCreation()