Button click inside a form

[NCP]

For a simple scenario, you can use a client script. For a complex scenario, you should use the frappe.call function.

Calling server script method in client script

frm.call please check the reference so you can understand of define the frm.call and frappe.call. Please check the set_missing_values method How to call in the sales_invoice.py Frappe Ajax Call reference documentation. Frappe Ajax Call I hope this helps. Thank You!