"""

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(maxlength=10, primary_key=True,

            db_column = 'code')

    first_name = models.CharField(maxlength=20)

    last_name = models.CharField(maxlength=20)

    class Meta:

        ordering = ('last_name', 'first_name')

    def __str__(self):

        return "%s %s" % (self.first_name, self.last_name)

class Business(models.Model):

    name = models.CharField(maxlength=20, primary_key=True)

    employees = models.ManyToManyField(Employee)

    class Meta:

        verbose_name_plural = 'businesses'

    def __str__(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>]

# 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'])

{'XYZ456': <Employee: Fran Jones>, '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'])

{'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>]

"""}