Want to customize Stock Ledger Entry

[revant_one]

How can I add validator to Purchase Order(or other system doctypes)?

@nnylyj ok, then you can use hooks to call validate method call your custom python function on validate event. add this in hooks.py under doc_events write your python function, you have access to all field value using self.field_name. To invalidate you can write frappe.throw(“message”)

add doc_events hook for Purchase Receipt and Purchase Invoice.

in the function, get_doc the related stock ledger entries and set values.