django-postgres-composite-types 0.4.2

Django Postgres composite types
===============================

An implementation of Postgres' [composite types](http://www.postgresql.org/docs/current/static/rowtypes.html)
for [Django](https://docs.djangoproject.com/en/1.9/).

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:

```python
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:

```python
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:

```python
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:

```python
class Point(CompositeType):
"""A point on the cartesian plane."""

# pylint:disable=invalid-name
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:

```python
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](https://github.com/danni/django-postgres-composite-types/issues/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](https://github.com/danni/django-postgres-composite-types/issues/9),
[bug #10](https://github.com/danni/django-postgres-composite-types/issues/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 py35-dj2.0

Authors
-------

* Danielle Madeley <danielle@madeley.id.au>
* Tim Heap <hello@timheap.me>

License
-------

(c) 2016, Danielle Madeley <danielle@madeley.id.au>

All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.

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this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.

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may be used to endorse or promote products derived from this software
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