Hello you can call onchange in xmlrpc by following way:

you can call onchage method like other method i.e. create, wrire

for example:

onchage_val = object_of_xmlrpc.execute( 'model.name',

'method_name', and parameters

)

ex:

SO_onchage = object_of_xmlrpc.execute(

'sale.order',

'onchange_partner_id',1, 30

)

where 1 is user_id,

30 is partner_id

Result = {'value': {'fiscal_position': False, 'user_id': 1, 'partner_shipping_id': 30, 'payment_term': 3, 'partner_invoice_id': 30, 'pricelist_id': 1}}

and for v8 it is call automatically when you pass you data in that particular onchange field.

hope so this will help you.