Odoo 18 Development Book-Extending Methods

In certain situations, it becomes important to introduce additional functionality to an existing Python method. This process is known as method extension. When adding new features or customizing existing model classes, it is often necessary to adjust or enhance the current business logic. As a result, we may need to update existing methods to support these new changes.

Let’s explore this concept through a practical example by extending a custom method. Imagine we have a model that manages all student records for a school.

from odoo import fields, models, api

class Student(models.Model):
    _name = "student.student"
    _description = "Student"

    name = fields.Char(string="Name", required=True)
    partner_id = fields.Many2one('res.partner', string="Partner")
    phone = fields.Char(string="Phone Number")
    email = fields.Char(string="Email", required=True)
    status = fields.Char(string="Status")

Place a button on the student form view to change the value of the student's status field.

<header>
    <button name="update_status" string="Update Status" class="oe_highlight" type="object"/>
</header>

Create the update_status() method in the Python file, where the write method is used to assign a new value to the status field of the student record.

def update_status(self):
   self.write({
       'status': "Status Updated"
   })

By inheriting the model, we can add a new date field named date_status_last_updated to record the last time the student's status was updated.

class StudentInherit(models.Model):
   _inherit = "student.student"

   date_status_last_updated = fields.Date(string="Status Updated Date")

By extending the update_status() method, we can also update the date_status_last_updated field. To accomplish this, you should define a method with the same name to extend the existing functionality. The super() function can then be used to call the original method from the parent class and execute its logic before adding the new operations.

In Odoo, it is common practice to override methods like create() and write() using super(). It is essential to ensure that when extending a method, all parameters from the original method are included in the extended version. Any additional arguments used in the parent method must also be passed to the overridden method.

The following example demonstrates the correct way to extend a method: it first performs all the actions from the parent method and then proceeds with the additional custom logic.

def update_status(self):
   res = super(Student, self).update_status()
   self.write({
       'date_status_last_updated': fields.Date.today()
   })
   return res

Overriding an existing method allows us to add new operations while preserving its existing behavior.