Hi,

You are essentially implementing cascading selection fields in product.template for Region → Area → Neighborhood. Since this is a custom extension to the standard Product model, the recommended approach is to create a small custom module, rather than modifying the core product module directly. Modifying the core module is risky because updates could break your customizations.

Follow the steps

Create a new custom module

    Example: product_location_extension

    Place your Python models, fields, and relationships here.

    Example structure:

    product_location_extension/

    ├── __init__.py

    ├── __manifest__.py

    ├── models/

    │   ├── __init__.py

    │   └── product_template_extension.py

    └── views/

        └── product_template_views.xml

Python Models

    In models/product_template_extension.py, inherit product.template:

from odoo import models, fields

class ProductTemplate(models.Model):

    _inherit = 'product.template'

    region_id = fields.Many2one('res.region', string='Region')

    area_id = fields.Many2one('res.area', string='Area', domain="[('region_id','=',region_id)]")

    neighborhood_id = fields.Many2one('res.neighborhood', string='Neighborhood', domain="[('area_id','=',area_id)]")

XML Views

    Extend the product.template form view:

<record id="view_product_template_form_inherit_location" model="ir.ui.view">

    <field name="name">product.template.form.location</field>

    <field name="model">product.template</field>

    <field name="inherit_id" ref="product.product_template_only_form_view"/>

    <field name="arch" type="xml">

        <xpath expr="//sheet/notebook/page[@string='General Information']" position="inside">

            <group>

                <field name="region_id"/>

                <field name="area_id"/>

                <field name="neighborhood_id"/>

            </group>

        </xpath>

    </field>

</record>

* Always use a separate custom module to extend product.template.

* Use Many2one fields with domains for cascading dropdowns.

* Keep models, views, and Python logic together in the module for maintainability.

Hope it helps