How to make primary contact as default of the account while creating SR

Summary

Map the account and primary contact in service request object

Content

Hi Team,

While creating service request from SR UI, based on the account the primary contact should be populated. As of now the standard functionality is based on the primary contact, the account was mapped automatically. But as per our requirement it should be from Account to Primary contact.

I have tried below script to achieve. But that is not working for me. 

def accountid = AccountPartyId
def ContactName
if(AccountPartyId != null)
{
def voBP = newView('SalesAccountVO');
def vcBP = voBP.createViewCriteria();
def vcrBP = vcBP.createRow();
def vciBP = vcrBP.ensureCriteriaItem('PartyId');