add new field on invoice

tra_backend_Product/models/account_move.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+
+from odoo import api, fields, models, _
+from odoo.exceptions import RedirectWarning, UserError, ValidationError, AccessError
+from datetime import date
+
+
+class AccountMove(models.Model):
+    _inherit = "account.move"
+
+
+    # ==== Business fields ====
+    overdue_by = fields.Float(string='Overdue By', index=True, compute='calculate_overdue_date')
+
+
+    def calculate_overdue_date(self):
+        current_date = date.today()
+        overdue_date = self.invoice_due_date - current_date
+        self.overdue_by = overdue_date.days
+