Using default_get() — Why Do Readonly Field Values Disappear After Saving in Odoo?

When customizing forms in Odoo, it’s quite common to use default_get() to automatically fill certain fields when creating a new record. In most situations, this works exactly as expected.

But things can get confusing when that field is marked as readonly.

You might have seen this happen:

• You define a field as readonly
• You populate its value using default_get()
• The value appears correctly when the form opens
• You save the record
• And suddenly… the value disappears

At first glance, this feels like a bug. But in reality, it’s just how Odoo’s web client is designed to work.

What’s Actually Happening Behind the Scenes?

When you open a new form view, Odoo calls the default_get() method to populate default values. These values are shown in the user interface — even for readonly fields.

However, during the save operation, the web client only sends back values that are considered editable or modified by the user.

Since readonly fields:

• Cannot be edited
• Are not changed by user interaction

They are treated as unchanged values, and therefore:

👉 They are not included in the data sent to the server when the record is saved.

As a result, the ORM never receives those values — and they are not stored in the database.

That’s why the value disappears after saving.

Reproducing the Issue

Python Model

from odoo import models, fields, api

class StudentRegistration(models.Model):
    _name = "student.registration"

    name = fields.Char(string="Student Name")
    reference_code = fields.Char(string="Reference Code", readonly=True)

    @api.model
    def default_get(self, fields_list):
        res = super().default_get(fields_list)
        res['reference_code'] = "REF-001"
        return res

XML View

<field name="reference_code" readonly="1"/>

Now:

• Open the form
• You’ll see the Reference Code is filled
• Click Save
• The value disappears

This happens because the readonly field was never sent back to the server during record creation.

UI-Level Fix: Using force_save="1"

If you want the readonly value from the form to be saved, you can instruct the web client to include it during submission by adding:

<field name="reference_code" readonly="1" force_save="1"/>

With this:

• The value is included in the save request
• The ORM receives it
• The value is stored correctly
• It remains visible after saving

This approach is useful when the value is mainly related to UI behavior and is expected to be created from the form itself.

Recommended Backend Approach: Assign Value in create()

If the value is important for business logic — like an internal reference, identifier, or workflow dependency — it’s better to assign it at the ORM level instead of relying on the form view.

Here’s how you can do that:

@api.model
def create(self, vals):
    if not vals.get('reference_code'):
        vals['reference_code'] = "REF-001"
    return super().create(vals)

This ensures the value is stored:

• Even if the record is created via API
• During CSV import
• From automated cron jobs
• Through external integrations

In other words, it works regardless of how the record is created — not just from the form view.

When Should You Use What?

Use force_save when:

• The field is readonly in the UI
• The value is assigned through the form
• The value is display-oriented

Use create() override when:

• The value is business-critical
• It must always be stored
• The record may be created through automation or integrations

When a readonly field is populated using default_get(), it may disappear after saving because readonly fields are not included in the form submission sent to the server.

This is expected behavior in Odoo — not a bug.

To make sure the value persists:

• Use force_save="1" for form-level persistence
• Or assign the value in create() for backend reliability

Understanding this small detail can save a lot of debugging time when developing custom Odoo modules.