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# -*- coding: utf-8 -*-
"""
14. Using a custom primary key
By default, Django adds an ``"id"`` field to each model. But you can override
this behavior by explicitly adding ``primary_key=True`` to a field.
"""
from django.db import models
class Employee(models.Model):
employee_code = models.CharField(max_length=10, primary_key=True,
db_column = 'code')
first_name = models.CharField(max_length=20)
last_name = models.CharField(max_length=20)
class Meta:
ordering = ('last_name', 'first_name')
def __unicode__(self):
return u"%s %s" % (self.first_name, self.last_name)
class Business(models.Model):
name = models.CharField(max_length=20, primary_key=True)
employees = models.ManyToManyField(Employee)
class Meta:
verbose_name_plural = 'businesses'
def __unicode__(self):
return self.name
__test__ = {'API_TESTS':"""
>>> dan = Employee(employee_code='ABC123', first_name='Dan', last_name='Jones')
>>> dan.save()
>>> Employee.objects.all()
[<Employee: Dan Jones>]
>>> fran = Employee(employee_code='XYZ456', first_name='Fran', last_name='Bones')
>>> fran.save()
>>> Employee.objects.all()
[<Employee: Fran Bones>, <Employee: Dan Jones>]
>>> Employee.objects.get(pk='ABC123')
<Employee: Dan Jones>
>>> Employee.objects.get(pk='XYZ456')
<Employee: Fran Bones>
>>> Employee.objects.get(pk='foo')
Traceback (most recent call last):
...
DoesNotExist: Employee matching query does not exist.
# Use the name of the primary key, rather than pk.
>>> Employee.objects.get(employee_code__exact='ABC123')
<Employee: Dan Jones>
# pk can be used as a substitute for the primary key.
>>> Employee.objects.filter(pk__in=['ABC123','XYZ456'])
[<Employee: Fran Bones>, <Employee: Dan Jones>]
# The primary key can be accessed via the pk property on the model.
>>> e = Employee.objects.get(pk='ABC123')
>>> e.pk
u'ABC123'
# Or we can use the real attribute name for the primary key:
>>> e.employee_code
u'ABC123'
# Fran got married and changed her last name.
>>> fran = Employee.objects.get(pk='XYZ456')
>>> fran.last_name = 'Jones'
>>> fran.save()
>>> Employee.objects.filter(last_name__exact='Jones')
[<Employee: Dan Jones>, <Employee: Fran Jones>]
>>> Employee.objects.in_bulk(['ABC123', 'XYZ456'])
{u'XYZ456': <Employee: Fran Jones>, u'ABC123': <Employee: Dan Jones>}
>>> b = Business(name='Sears')
>>> b.save()
>>> b.employees.add(dan, fran)
>>> b.employees.all()
[<Employee: Dan Jones>, <Employee: Fran Jones>]
>>> fran.business_set.all()
[<Business: Sears>]
>>> Business.objects.in_bulk(['Sears'])
{u'Sears': <Business: Sears>}
>>> Business.objects.filter(name__exact='Sears')
[<Business: Sears>]
>>> Business.objects.filter(pk='Sears')
[<Business: Sears>]
# Queries across tables, involving primary key
>>> Employee.objects.filter(business__name__exact='Sears')
[<Employee: Dan Jones>, <Employee: Fran Jones>]
>>> Employee.objects.filter(business__pk='Sears')
[<Employee: Dan Jones>, <Employee: Fran Jones>]
>>> Business.objects.filter(employees__employee_code__exact='ABC123')
[<Business: Sears>]
>>> Business.objects.filter(employees__pk='ABC123')
[<Business: Sears>]
>>> Business.objects.filter(employees__first_name__startswith='Fran')
[<Business: Sears>]
# Primary key may be unicode string
>>> emp = Employee(employee_code='jaźń')
>>> emp.save()
"""}
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