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Django PostgreSQL netfields implementation

Project description

This project is an attempt at making proper PostgreSQL net related fields for Django. In Django pre 1.4 the built in IPAddressField does not support IPv6 and uses an inefficient HOST() cast in all lookups. As of 1.4 you can use GenericIPAddressField for IPv6, but the casting problem remains.

In addition to the basic IPAddressField replacement, InetAddressField, a CidrAddressField a MACAddressField, and a MACAddress8Field have been added. This library also provides a manager that allows for advanced IP based lookups directly in the ORM.

In Python, the values of the IP address fields are represented as types from the ipaddress module. In Python 2.x, a backport is used. The MAC address fields are represented as EUI types from the netaddr module.

Dependencies

This module requires Django >= 1.11, psycopg2, and netaddr.

Installation

$ pip install django-netfields

Getting started

Make sure netfields is in your PYTHONPATH and in INSTALLED_APPS.

InetAddressField will store values in PostgreSQL as type INET. In Python, the value will be represented as an ipaddress.ip_interface object representing an IP address and netmask/prefix length pair unless the store_prefix_length argument is set to False, in which case the value will be represented as an ipaddress.ip_address object.

from netfields import InetAddressField, NetManager

class Example(models.Model):
    inet = InetAddressField()
    # ...

    objects = NetManager()

CidrAddressField will store values in PostgreSQL as type CIDR. In Python, the value will be represented as an ipaddress.ip_network object.

from netfields import CidrAddressField, NetManager

class Example(models.Model):
    inet = CidrAddressField()
    # ...

    objects = NetManager()

MACAddressField will store values in PostgreSQL as type MACADDR. In Python, the value will be represented as a netaddr.EUI object. Note that the default text representation of EUI objects is not the same as that of the netaddr module. It is represented in a format that is more commonly used in network utilities and by network administrators (00:11:22:aa:bb:cc).

from netfields import MACAddressField, NetManager

class Example(models.Model):
    inet = MACAddressField()
    # ...

MACAddress8Field will store values in PostgreSQL as type MACADDR8. In Python, the value will be represented as a netaddr.EUI object. As with MACAddressField, the representation is the common one (00:11:22:aa:bb:cc:dd:ee).

from netfields import MACAddress8Field, NetManager

class Example(models.Model):
    inet = MACAddress8Field()
    # ...

For InetAddressField and CidrAddressField, NetManager is required for the extra lookups to be available. Lookups for INET and CIDR database types will be handled differently than when running vanilla Django. All lookups are case-insensitive and text based lookups are avoided whenever possible. In addition to Django’s default lookup types the following have been added:

__net_contained

is contained within the given network

__net_contained_or_equal

is contained within or equal to the given network

__net_contains

contains the given address

__net_contains_or_equals

contains or is equal to the given address/network

__net_overlaps

contains or contained by the given address

__family

matches the given address family

__host

matches the host part of an address regardless of prefix length

__prefixlen

matches the prefix length part of an address

These correspond with the operators and functions from http://www.postgresql.org/docs/9.4/interactive/functions-net.html

CidrAddressField includes two extra lookups (these will be depreciated in the future by __prefixlen):

__max_prefixlen

Maximum value (inclusive) for CIDR prefix, does not distinguish between IPv4 and IPv6

__min_prefixlen

Minimum value (inclusive) for CIDR prefix, does not distinguish between IPv4 and IPv6

Database Functions

Postgres network address functions are exposed via the netfields.functions module. They can be used to extract additional information from these fields or to construct complex queries.

from django.db.models import F

from netfields import CidrAddressField, NetManager
from netfields.functions import Family, Masklen

class Example(models.Model):
    inet = CidrAddressField()
    # ...

ipv4_with_num_ips = (
    Example.objects.annotate(
        family=Family(F('inet')),
        num_ips=2 ** (32 - Masklen(F('inet')))  # requires Django >2.0 to resolve
    )
    .filter(family=4)
)

CidrAddressField and InetAddressField Functions

Postgres Function

Django Function

Return Type

Description

abbrev(T)

Abbrev

TextField

abbreviated display format as text

broadcast(T)

Broadcast

InetAddressField

broadcast address for network

family(T)

Family

IntegerField

extract family of address; 4 for IPv4, 6 for IPv6

host(T)

Host

TextField

extract IP address as text

hostmask(T)

Hostmask

InetAddressField

construct host mask for network

masklen(T)

Masklen

IntegerField

extract netmask length

netmask(T)

Netmask

InetAddressField

construct netmask for network

network(T)

Network

CidrAddressField

extract network part of address

set_masklen(T, int)

SetMasklen

T

set netmask length for inet value

text(T)

AsText

TextField

extract IP address and netmask length as text

inet_same_family(T, T)

IsSameFamily

BooleanField

are the addresses from the same family?

inet_merge(T, T)

Merge

CidrAddressField

the smallest network which includes both of the given networks

MACAddressField Functions

Postgres Function

Django Function

Return Type

Description

trunc(T)

Trunc

T

set last 3 bytes to zero

MACAddress8Field Functions

Postgres Function

Django Function

Return Type

Description

trunc(T)

Trunc

T

set last 5 bytes to zero

macaddr8_set7bit(T)

Macaddr8Set7bit

T

set 7th bit to one. Used to generate link-local IPv6 addresses

Indexes

As of Django 2.2, indexes can be created for InetAddressField and CidrAddressField extra lookups directly on the model.

from django.contrib.postgres.indexes import GistIndex
from netfields import CidrAddressField, NetManager

class Example(models.Model):
    inet = CidrAddressField()
    # ...

    class Meta:
        indexes = (
            GistIndex(
                fields=('inet',), opclasses=('inet_ops',),
                name='app_example_inet_idx'
            ),
        )

For earlier versions of Django, a custom migration can be used to install an index.

from django.db import migrations

class Migration(migrations.Migration):
    # ...

    operations = [
        # ...
        migrations.RunSQL(
            "CREATE INDEX app_example_inet_idx ON app_example USING GIST (inet inet_ops);"
        ),
        # ...
    ]

Similar projects

https://bitbucket.org/onelson/django-ipyfield tries to solve some of the same issues as this library. However, instead of supporting just postgres via the proper fields types the ipyfield currently uses a VARCHAR(39) as a fake unsigned 64 bit number in its implementation.

History

Main repo was originally kept https://github.com/adamcik/django-postgresql-netfields Late April 2013 the project was moved to https://github.com/jimfunk/django-postgresql-netfields to pass the torch on to someone who actually uses this code actively :-)

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