Django Postgres composite types
An implementation of Postgres' composite types for Django.
Usage
Install with:
pip install django-postgres-composite-types
Then add 'postgres_composite_types' to your INSTALLED_APPS:
INSTALLED_APPS = [
# ... Other apps
'postgres_composite_types',
]
Define a type and add it to a model:
from django.db import models
from postgres_composite_types import CompositeType
class Address(CompositeType):
"""An address."""
address_1 = models.CharField(max_length=255)
address_2 = models.CharField(max_length=255)
suburb = models.CharField(max_length=50)
state = models.CharField(max_length=50)
postcode = models.CharField(max_length=10)
country = models.CharField(max_length=50)
class Meta:
db_type = 'x_address' # Required
class Person(models.Model):
"""A person."""
address = Address.Field()An operation needs to be prepended to your migration:
import address
from django.db import migrations
class Migration(migrations.Migration):
operations = [
# Registers the type
address.Address.Operation(),
migrations.AddField(
model_name='person',
name='address',
field=address.Address.Field(blank=True, null=True),
),
]Examples
Array fields:
class Card(CompositeType):
"""A playing card."""
suit = models.CharField(max_length=1)
rank = models.CharField(max_length=2)
class Meta:
db_type = 'card'
class Hand(models.Model):
"""A hand of cards."""
cards = ArrayField(base_field=Card.Field())Nested types:
class Point(CompositeType):
"""A point on the cartesian plane."""
x = models.IntegerField()
y = models.IntegerField()
class Meta:
db_type = 'x_point' # Postgres already has a point type
class Box(CompositeType):
"""An axis-aligned box on the cartesian plane."""
class Meta:
db_type = 'x_box' # Postgres already has a box type
top_left = Point.Field()
bottom_right = Point.Field()Gotchas and Caveats
The migration operation currently loads the current state of the type, not
the state when the migration was written. A generic CreateType operation
which takes the fields of the type would be possible, but it would still
require manual handling still as Django's makemigrations is not currently
extensible.
Changes to types are possible using RawSQL, for example:
operations = [
migrations.RunSQL([
"ALTER TYPE x_address DROP ATTRIBUTE country",
"ALTER TYPE x_address ADD ATTRIBUTE country integer",
], [
"ALTER TYPE x_address DROP ATTRIBUTE country",
"ALTER TYPE x_address ADD ATTRIBUTE country varchar(50)",
]),
]However, be aware that if your earlier operations were run using current DB code, you will already have the right types (bug #8).
It is recommended to that you namespace your custom types to avoid conflict with future PostgreSQL types.
Lookups and indexes are not implemented yet (bug #9, bug #10).
Running Tests
Clone the repository, go to it's base directory and run the following commands.
pip install tox
tox
Or if you want a specific environment
tox -e py311-dj41
Authors
- Danielle Madeley danielle@madeley.id.au
- Tim Heap hello@timheap.me
License
This project is licensed under the BSD license. See the LICENSE file for the full text of the license.
