*Add source code in your module as per below example.

def _compute_invoice_count(self)
for rec in self:
rec.invoice_count = len(rec.invoice_ids)

invoice_count = field.Integer("Invoice Count", compute="_compute_invoice_count")
invoice_ids = field.One2Many("account.move", "sale_id")

def method_name(self):
return {
"name": "Invoice",
"type": "ir.actions.act_window",
"view_mode": "tree,form",
"res_model": "account.move",
"domain": [("sale_id", "=", self.id)],
}