How to Create & Manage Custom Fields from Functions in Odoo 18

In modern ERP systems, static data is rarely enough. Businesses often need fields that respond intelligently to other data points—calculating credit scores based on payment history, determining delivery priorities based on location, or grading customer loyalty based on sales volume. Odoo 18 handles this elegantly through Computed Fields.

This tutorial explores how to create and manage custom fields using Python functions in Odoo 18. We will move beyond simple data entry and build a dynamic "Customer Loyalty Score" system that automatically updates based on a customer's purchase history. This approach ensures your data remains live, accurate, and actionable without manual intervention.

The Scenario: Customer Loyalty Scoring

We want to add a field called Loyalty Tier to the Contact form. Instead of manually selecting "Gold" or "Silver," the system should calculate this automatically based on the total confirmed sales orders linked to that customer.

• Platinum: Sales > $10,000
• Gold: Sales > $5,000
• Silver: Sales > $1,000
• Bronze: Sales <= $1,000

Step 1: Inherit the Model

First, we create a new Python file in our custom module's models directory. We need to inherit the res.partner model to add our new field.

from odoo import models, fields, api

class ResPartner(models.Model):
    _inherit = 'res.partner'

    loyalty_tier = fields.Selection([
        ('platinum', 'Platinum'),
        ('gold', 'Gold'),
        ('silver', 'Silver'),
        ('bronze', 'Bronze')
    ], string='Loyalty Tier', compute='_compute_loyalty_tier', store=True)

    @api.depends('sale_order_ids.amount_total', 'sale_order_ids.state')
    def _compute_loyalty_tier(self):
        for partner in self:
            # Calculate total confirmed sales
            total_sales = sum(
                order.amount_total 
                for order in partner.sale_order_ids 
                if order.state in ['sale', 'done']
            )

            # Assign Tier
            if total_sales >= 10000:
                partner.loyalty_tier = 'platinum'
            elif total_sales >= 5000:
                partner.loyalty_tier = 'gold'
            elif total_sales >= 1000:
                partner.loyalty_tier = 'silver'
            else:
                partner.loyalty_tier = 'bronze'

Step 2: Understanding @api.depends

The @api.depends decorator is critical for performance and correctness. It tells Odoo when to re-calculate the field.

In our code: @api.depends('sale_order_ids.amount_total', 'sale_order_ids.state') ensures the function runs whenever:

• A new Sales Order is linked to the partner.
• A Sales Order's total amount changes.
• A Sales Order's state changes (e.g., from 'Draft' to 'Sale').

Step 3: Add to the User Interface

Now that the backend logic is ready, we need to display the field on the Contact form. We'll add it right below the tags.

<odoo>
    <record id="view_partner_form_inherit_loyalty" model="ir.ui.view">
        <field name="name">res.partner.form.inherit.loyalty</field>
        <field name="model">res.partner</field>
        <field name="inherit_id" ref="base.view_partner_form"/>
        <field name="arch" type="xml">
            <xpath expr="//field[@name='category_id']" position="after">
                <field name="loyalty_tier" 
                       widget="badge" 
                       decoration-warning="loyalty_tier == 'gold'" 
                       decoration-info="loyalty_tier == 'platinum'"
                       decoration-muted="loyalty_tier == 'silver'"/>
            </xpath>
        </field>
    </record>
</odoo>

We use the widget="badge" and decoration-* attributes to give the field a visual pop, making the tiers instantly recognizable with colors.

Step 4: Update the Manifest

Don't forget to include the new view file in your module's manifest.

{
    'name': 'Customer Loyalty',
    'version': '18.0.1.0.0',
    'depends': ['base', 'sale_management'],
    'data': [
        'views/res_partner_views.xml',
    ],
    'installable': True,
}

Why Use Computed Fields?

Advanced Tips for Developers

• Inverse Functions: You can make computed fields editable by defining an inverse function that writes changes back to the source fields.
• Performance: Avoid complex calculations (like searching millions of records) inside strict loops. Use standard Python optimization and Odoo's read_group when aggregating large datasets.
• Search Functions: To search on a non-stored computed field, you must define a custom search method.

Frequently Asked Questions