Odoo 18 Development Book: Computed fields

In real-world business logic, certain field values must be derived automatically based on other fields in the same or related records. Computed fields in Odoo 18 provide a powerful solution for such cases. These fields are not manually inputted; instead, their values are dynamically calculated through functions defined in the model.

A computed field is declared in a similar way to regular fields, with one additional argument: the compute attribute, which points to the function that will calculate the field’s value.

from odoo import models, fields, api

class YourModel(models.Model):
    _name = 'your.model'

    total = fields.Float(string="Total", compute="_compute_total")

    @api.depends('some_field')
    def _compute_total(self):
        for rec in self:
            rec.total = rec.some_field * 2  # Example computation

The function _compute_total performs the actual calculation. Computed fields, by default, are not stored, not writable, and not searchable, unless you explicitly configure them to be.

Dependencies

To ensure the compute method runs only when necessary, you must declare field dependencies using the @api.depends() decorator. This tells Odoo which fields to monitor for changes that should trigger recomputation.

Example:

from odoo import models, fields, api

class YourModel(models.Model):
    _name = 'your.model'

    amount = fields.Float(string='Amount')
    total = fields.Float(string='Total', compute="_compute_total")

    @api.depends('amount')
    def _compute_total(self):
        for rec in self:
            rec.total = 2.0 * rec.amount

When the amount field changes, _compute_total() is automatically triggered to update the total field.

Storing Computed Fields

By default, computed fields are not stored in the database; they are calculated on the fly. If you want the value to be saved in the database, use the store=True attribute.

from odoo import models, fields, api

class YourModel(models.Model):
    _name = 'your.model'

    amount = fields.Float(string='Amount')
    total = fields.Float(string='Total', compute="_compute_total", store=True)

    @api.depends('amount')
    def _compute_total(self):
        for rec in self:
            rec.total = 2.0 * rec.amount

This makes the computed field behave like a regular stored field—allowing you to search on it, filter it, or export it without runtime recalculation. Odoo’s ORM ensures that stored values are updated automatically when any of the dependencies change.

Inverse Function

Since computed fields are read-only by default, users cannot modify them manually. However, there may be situations where you want to allow the user to set a value for a computed field, and then update related fields accordingly. This is done using an inverse method.

from odoo import models, fields, api

class YourModel(models.Model):
    _name = 'your.model'

    amount = fields.Float(string="Amount")
    total = fields.Float(string='Total', compute="_compute_total", inverse="_inverse_total")

    @api.depends("amount")
    def _compute_total(self):
        for record in self:
            record.total = 2.0 * record.amount

    def _inverse_total(self):
        for record in self:
            record.amount = record.total / 2.0

• The compute method calculates the value based on amount.
• The inverse method allows users to enter a value in total, and then automatically updates the amount.

The inverse function is triggered when the record is saved, while the compute function is triggered when any of its dependencies change.