Making a django model field readonly

Question

I am creating a django DB model and I want one the fields to be readonly. When creating a new object I want to set it, but later if someone tries to update the object, it should raise an error. How do I achieve that?

I tried the following but I was still able to update the objects.

from django.db import models as django_db_models


class BalanceHoldAmounts(django_db_models.Model):
    read_only_field = django_db_models.DecimalField(editable=False)

Thank you

you can find multiple solution here https://stackoverflow.com/questions/324477/in-a-django-form-how-do-i-make-a-field-readonly-or-disabled-so-that-it-cannot — Tanveer Ahmad, Feb 06 '23 at 12:50
I am not using django to create forms. I use it only as a DB ORM for my backend. — Epic, Feb 06 '23 at 13:17

R D · Answer 1 · 2023-02-06T16:08:01.880

0

You can override it in the "save" method of the model and raise a Validation Error if someone tries to update that field.

def save(self, *args, **kwargs):
    if self.pk:
        previous_value = BalanceHoldAmounts.objects.get(pk=self.pk)
        if previous_value.read_only_field != self.read_only_field:
            raise ValidationError("The read_only_field can not be changed")    
    super().save(*args, **kwargs)

edited Feb 06 '23 at 16:08

answered Feb 06 '23 at 15:15

R D

1
3

Warning! This won't save if the object doesn't have an id! That only makes it readonly once the object is created! – Maël Pedretti Feb 06 '23 at 15:48
1

Indentation was mistaken in earlier code. I have corrected it. Other are fine – R D Feb 06 '23 at 16:17

Making a django model field readonly

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