add new field on invoice

tra_backend_Product/__manifest__.py

@@ -10,11 +10,12 @@
     'author': 'Masterkey',
     'description': "",
     'website': 'https://www.odoo.com/page/crm',
-    'depends': ['product','base','sale_renting'
+    'depends': ['product','base','sale_renting','account'
     ],
     'data': [
         'views/product_views.xml',
-	'views/partner_view.xml',
+	    'views/partner_view.xml',
+        'views/account_move_view.xml'
     ],
     'demo': [
        

tra_backend_Product/models/__init__.py

@@ -4,3 +4,4 @@
 
 from . import product
 from . import partner
+from . import account_move

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
+

tra_backend_Product/views/account_move_view.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<odoo>
+    <data>
+
+   <!-- view common to both template and product -->
+
+        <record id="view_invoice_tree_inherit" model="ir.ui.view">
+            <field name="name">account.invoice.tree</field>
+            <field name="model">account.move</field>
+            <field name="inherit_id" ref="account.view_invoice_tree"/>
+            <field name="arch" type="xml">
+            	<xpath expr="//field[@name='invoice_date_due']" position="after">
+                    <field name="overdue_by"/>
+                </xpath>  
+        </record>
+       
+
+</data>
+</odoo>