I want to send context when call method in class osv.osv from models.Model (new api) like this :

In models.Model :

ctx = {'key' : 'value'}

self.picking_id.do_transfer(context=ctx)

In osv.osv :

@api.cr_uid_ids_context

def do_transfer(self, cr, uid, picking_ids, context=None):

print "context.get('key')================>>>>>>>>>>>>>>>>",context.get('key')

return True

And result from print is :

context.get('key')================>>>>>>>>>>>>>>>> None

Why the result is None ?