Registry / database / django-add-default-value

django-add-default-value

library0.10.0pypypi✓ verified 86d ago

django-add-default-value is a Django Migration Operation that facilitates transferring a field's default value directly to the database schema. This addresses Django's default behavior of handling `default` values at the application level and dropping the database `DEFAULT` constraint after initial row population. The library is currently active, with version 0.10.0 released in February 2022, and helps ensure database-level default constraints persist for improved data integrity and compatibility with non-Django database access.

database web-framework

pip install django-add-default-value

github ↗package ↗

INSTALL

IMPORT

SIG · DJANGO-ADD-DEFAULT

django-add-default-value

databasepythonv0.10.0

Install

3.4s avg

Import

668ms

Disk

65MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v0.10.0 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.920 runs

installs and imports cleanly · install 0.0s · import 0.704s · 66.3MB

glibc

py 3.10–3.920 runs

installs and imports cleanly · install 3.4s · import 0.632s · 67MB

65MB installed

● package 65MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

AddDefaultValue

✓ from django_add_default_value import AddDefaultValue

To use `django-add-default-value`, manually add the `AddDefaultValue` operation to an autogenerated migration file immediately after an `AddField` operation. This ensures that the specified default value for the field is transferred to the database schema, maintaining the default constraint at the database level.

import os import django from django.conf import settings from django.db import migrations, models from django_add_default_value import AddDefaultValue # Minimal Django setup for demonstration if not settings.configured: settings.configure( INSTALLED_APPS=['my_app'], DATABASES={'default': {'ENGINE': 'django.db.backends.sqlite3', 'NAME': ':memory:'}} ) django.setup() # Example of a migration file using AddDefaultValue class Migration(migrations.Migration): dependencies = [ # ... other app dependencies ] operations = [ migrations.AddField( model_name='my_model', name='my_field', field=models.CharField(default='my_default_value', max_length=255), ), AddDefaultValue( model_name='my_model', name='my_field', value='my_default_value' ) ]

Debug

Known issues

gotchaDjango's default migration behavior does not typically set persistent database-level DEFAULT constraints for model fields. It applies a one-off default to existing rows and then drops the database constraint, relying on the application to enforce defaults for new records. This can lead to inconsistencies or issues with non-Django database interactions.

fix

Use `django-add-default-value.AddDefaultValue` in your migrations for critical fields to ensure the database schema itself enforces the default, or leverage Django's `db_default` option (available in Django 4.2+).

affects: All Django versions (without explicit `db_default` or similar)

breakingWhen adding a new non-nullable field to an existing model without explicitly providing a `default` in `models.py`, `makemigrations` will prompt you to provide a 'one-off' default. This default is temporary and only used to populate existing rows, not to establish a persistent database-level default.

fix

To establish a persistent database default, either add `default='some_value'` to your model field and then use `AddDefaultValue` in the migration, or, for simple static defaults, define `db_default` directly on the field (Django 4.2+).

affects: All Django versions

gotchaUsing callable functions as `default` values in Django models (e.g., `default=uuid.uuid4`). Django executes the callable once during migration to populate existing rows and then drops the database default, relying on Python to call the function for new object creation. This means the database schema itself won't have a dynamic default constraint.

fix

For callable defaults, `django-add-default-value` might not be the direct solution for dynamic database defaults (as SQL defaults are often static). Consider if a database-level default is truly required, or if application-level enforcement is sufficient. If a static default based on the callable's *initial* value is acceptable for the database, `AddDefaultValue` can be used with that static value.

affects: All Django versions

Errors

Common errors & fixes

It is impossible to add a non-nullable field '...' to ... without specifying a default.

Attempting to add a new non-nullable field to a model that already contains data, without providing a default value in `models.py` or through the migration prompt. Django needs a value to populate existing rows.

fix

Edit your generated migration file to include `AddDefaultValue(model_name='...', name='...', value='...')` after `migrations.AddField`. Alternatively, add `default='some_value'` to the field definition in `models.py` before `makemigrations` and then include `AddDefaultValue`.

django.db.utils.IntegrityError: NOT NULL constraint failed: my_app_my_model.my_field

A new non-nullable field was added without a persistent database-level default. When new records are inserted (e.g., directly into the database, or by a non-Django process), and no value is provided for 'my_field', the database's NOT NULL constraint is violated.

fix

Ensure `AddDefaultValue` is used in the migration that adds the non-nullable field. This establishes a `DEFAULT` constraint at the database level, preventing `NOT NULL` violations when no value is explicitly provided. Run `python manage.py migrate` to apply the migration.

ModuleNotFoundError: No module named 'django_add_default_value'

The `django-add-default-value` package is not installed in the active Python environment, or there's a typo in the import statement.

fix

Run `pip install django-add-default-value` to install the library. Verify the import statement is `from django_add_default_value import AddDefaultValue`.

Upgrade

Version history

0.10.0latest on PyPI · released Feb 2, 2022

Audit

Dependencies

DjangorequiredCore framework dependency for migration operations.

MySQLoptionalExplicitly supported database backend.

PostgreSQLoptionalExplicitly supported database backend.

MSSQLoptionalExplicitly supported database backend (currently not tested by library maintainers).

CockroachDBoptionalExplicitly supported database backend.

Agent activity

13 hits · last 30 days

node

Resources

githubhttps://github.com/3YOURMIND/django-add-default-value ↗

packagehttps://pypi.org/project/django-add-default-value/ ↗