What is a Computed Field?
In Odoo, a calculated field is one that determines its value by using the values of other fields. Computed fields, in contrast to ordinary fields, do not save data in the database unless specifically designated. They are frequently applied to quantities that vary dynamically, such as percentages, total prices, or derived statistics.
Why Use an Inverse Function?
Without an inverse function, calculated fields are read-only. Adding an inverse function allows you to change these fields. When a user changes a computed field, the inverse function updates the fields used in the computation to ensure data consistency.
This blog discusses the implementation, use, and significance of adding an inverse function for computed fields in Odoo 18. We’ll also go over an example to show how it can be used in real-life applications.
Defining a Computed Field
To define a calculated field in Odoo, include the compute parameter in the field definition.
For example:
from odoo import models, fields
class MyModel(models.Model):
_name = 'my.model'
name = fields.Char(string="Name")
amount = fields.Float(string="Amount")
tax = fields.Float(string="Tax")
total = fields.Float(string="Total", compute='_compute_total’)
@api.depends(‘amount’, ‘tax’)
def _compute_total(self):
for record in self:
record.total = record.amount + record.tax
Here, the '_compute_total' method is used to calculate the 'total' field. the function adds the 'amount' and ‘tax’. Whenever 'amount' or 'tax' changes, the '@api.depends' decorator makes sure that the 'total' is updated.
Limitation of Computed Fields
By default, computed fields are read-only, which means they cannot be modified directly in the user interface. Odoo automatically generates their values based on their fields.
While calculated fields are useful for automating computations, there may be times when you want users to manually modify these fields, while logic adjusts other fields accordingly.
Suppose a calculated field that defines the entire cost, for instance. You might want the unit pricing or quantities of the related goods to be automatically changed if a user makes a manual change to this total price. The inverse function is used in this situation.
Inverse Function Syntax
To add an inverse function to a calculated field, use the following general syntax:
from odoo import models, fields
class MyModel(models.Model):
_name = 'my.model'
name = fields.Char(string="Name")
amount = fields.Float(string="Amount")
tax = fields.Float(string="Tax")
total = fields.Float(string="Total", compute='_compute_total', inverse='_inverse_total')
def _compute_total(self):
for record in self:
record.total = record.amount + record.tax
def _inverse_total(self):
for record in self:
# Example logic: If total is set, recalculate amount and tax
if record.total:
record.tax = record.total - record.amount
In this example, the '_compute_total' method is used to generate the 'total' field, and when the user modifies 'total,' the '_inverse_total' function updates the tax of the linked lines.
Components of the Inverse Function
* compute='_compute_total': This argument defines the function that calculates the field's value.
* inverse='_inverse_total': This option specifies the function that is used to update the related fields when the computed field (total) is manually modified.
By changing linked fields according to the updated value of the computed field, the inverse function enables you to preserve consistency across fields.
How to Configure a Computed Field with an Inverse Function in Odoo 18
Use these steps to configure a field in Odoo with an inverse function:
- Define the computed field: Create a field with a compute parameter, set store=True if you want it saved in the database, and include the inverse attribute for manual updates.
- Define the Compute Method: Using information from other fields, this function determines the value of the calculated field.
- Define the Inverse Method: This function allows you to manually modify the calculated field, which updates linked fields as it changes.
Conclusion
Using inverse functions with computed fields in Odoo 18 enables developers to create extremely dynamic and flexible models that respond to user inputs while ensuring data integrity.
Combining calculated and inverse functions ensures that changes to one area are reflected in related fields, improving both usability and data integrity.
Inverse functions give your Odoo apps critical flexibility, allowing for smooth user experiences and effective data management whether you're handling time-sensitive data, dynamic pricing, or discounts.
You can successfully use inverse functions in your Odoo 18 customization by offering these guidelines and best practices.
