Skip to main content

Extended Django Model class with composite-primary-key support

Project description


Provide an extended Django Model class named 'CPkModel' that supports composite primary keys. Also provide an extended Query class 'CPkQuery' that supports multi-column lookups.

This package supports treating legacy db tables with a composite primary key, without adding a surrogate key.

This is my other approach to ticket373.


1. Easy to use

For a table with a composite primary key, change the base class from Model to CPkModel, and set 'unique_together' in Meta. In addition, set 'primary_key=True' to each primary keys.

(model definition sample)

from django.db import models
from cpkmodel import CPkModel

# Normal Model
#   primary_key is auto 'id'
class Company(models.Model):
    name = models.CharField(max_length=100)
    established_date = models.DateField()
    company_code = models.CharField(max_length=100)

    class Meta:
        db_table = 'Company'

# Child Model (CpkModel)
#   composite primary key: company_id, country_code
class CompanyBranch(CPkModel):
    company = models.ForeignKey(
        primary_key=True,       # for CompositePK
    country_code = models.CharField(
        primary_key=True,       # for CompositePK
    name = models.CharField(max_length=100)
    established_date = models.DateField()

    class Meta:
        db_table = 'CompanyBranch'
        unique_together = (('company', 'country_code'),)  # for CompositePK

That's all. No additional definitions or virtual fields are required.

2. Admin avairable

CPkModel can be used in Django Admin. The values of composite primary key are displayed in a comma separated style. Change(Update), Delete are fine. Add(Create) has a problem that CreateView do unique check to each key Field. So you can't add enough child records. But, this is only CreateView's problem. Your program can create child records by QuerySet or Model method.

3. Multi-column lookup avairable

To support composite primary keys, CPkQuery supports multi-column lookups.

obj = CompanyBranch.objects.get(pk=(1,'JP'))
qs = CompanyBranch.objects.filter(pk='1,JP')
qs = CompanyBranch.objects.filter(**{'company,country_code':(1,'JP')})
qs = CompanyBranch.objects.filter(**{'company_id,country_code':'1,JP'})

LHS with comma is not just primary, also other columns are OK.

qs = CompanyBranch.objects.filter(**{'country_code,name':'JP,Google'})

Lookup Multi-Column with 'in' is also avairable. PostgreSQL is fine, But SQLite3 is not supported.

qs = CompanyBranch.objects.filter(pk__in=[(1,'JP'),(1,'US'),(2,'JP'),])
qs = CompanyBranch.objects.filter(**{'country_code,name__in':[('JP','HONDA'),('CN','SONY'),]})

4. bulk_update avairable (v1.0.2)

bulk_update methond avairable for PostgreSQL. But SQLite3 is not supported.

   Album.objects.bulk_update(albums, ['num_stars',])


pip install django-compositepk-model


Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

django-compositepk-model-1.0.2.tar.gz (7.0 kB view hashes)

Uploaded Source

Built Distribution

django_compositepk_model-1.0.2-py3-none-any.whl (9.0 kB view hashes)

Uploaded Python 3

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page