How to apply Patch for updating party_name in GL entry?

Frappe Framework App Development
1

Hi,
I have a created custom field party_name in gl_entry and also written code in patch to update party_name in GL Entry from customer(party in gl_entry) .But its not working …
Can anyone helpme ??? How to write a sample code for updating value to field .

2

Try this
cur_frm.add_fetch('*Source field name*', '*Source*','*Target*');

3

Thank u @rk_root i will check.

4

@rk_root
Try this
cur_frm.add_fetch(‘Source field name’, ‘Source’,‘Target’);

It is also not working.