1 """

     2 14. Using a custom primary key

     3 

     4 By default, Django adds an ``"id"`` field to each model. But you can override

     5 this behavior by explicitly adding ``primary_key=True`` to a field.

     6 """

     7 

     8 from django.db import models

     9 

    10 class Employee(models.Model):

    11     employee_code = models.CharField(maxlength=10, primary_key=True,

    12             db_column = 'code')

    13     first_name = models.CharField(maxlength=20)

    14     last_name = models.CharField(maxlength=20)

    15     class Meta:

    16         ordering = ('last_name', 'first_name')

    17 

    18     def __str__(self):

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

    20 

    21 class Business(models.Model):

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

    23     employees = models.ManyToManyField(Employee)

    24     class Meta:

    25         verbose_name_plural = 'businesses'

    26 

    27     def __str__(self):

    28         return self.name

    29 

    30 __test__ = {'API_TESTS':"""

    31 >>> dan = Employee(employee_code='ABC123', first_name='Dan', last_name='Jones')

    32 >>> dan.save()

    33 >>> Employee.objects.all()

    34 [<Employee: Dan Jones>]

    35 

    36 >>> fran = Employee(employee_code='XYZ456', first_name='Fran', last_name='Bones')

    37 >>> fran.save()

    38 >>> Employee.objects.all()

    39 [<Employee: Fran Bones>, <Employee: Dan Jones>]

    40 

    41 >>> Employee.objects.get(pk='ABC123')

    42 <Employee: Dan Jones>

    43 >>> Employee.objects.get(pk='XYZ456')

    44 <Employee: Fran Bones>

    45 >>> Employee.objects.get(pk='foo')

    46 Traceback (most recent call last):

    47     ...

    48 DoesNotExist: Employee matching query does not exist.

    49 

    50 # Use the name of the primary key, rather than pk.

    51 >>> Employee.objects.get(employee_code__exact='ABC123')

    52 <Employee: Dan Jones>

    53 

    54 # pk can be used as a substitute for the primary key.

    55 >>> Employee.objects.filter(pk__in=['ABC123','XYZ456'])

    56 [<Employee: Fran Bones>, <Employee: Dan Jones>]

    57 

    58 # Fran got married and changed her last name.

    59 >>> fran = Employee.objects.get(pk='XYZ456')

    60 >>> fran.last_name = 'Jones'

    61 >>> fran.save()

    62 >>> Employee.objects.filter(last_name__exact='Jones')

    63 [<Employee: Dan Jones>, <Employee: Fran Jones>]

    64 >>> Employee.objects.in_bulk(['ABC123', 'XYZ456'])

    65 {'XYZ456': <Employee: Fran Jones>, 'ABC123': <Employee: Dan Jones>}

    66 

    67 >>> b = Business(name='Sears')

    68 >>> b.save()

    69 >>> b.employees.add(dan, fran)

    70 >>> b.employees.all()

    71 [<Employee: Dan Jones>, <Employee: Fran Jones>]

    72 >>> fran.business_set.all()

    73 [<Business: Sears>]

    74 >>> Business.objects.in_bulk(['Sears'])

    75 {'Sears': <Business: Sears>}

    76 

    77 >>> Business.objects.filter(name__exact='Sears')

    78 [<Business: Sears>]

    79 >>> Business.objects.filter(pk='Sears')

    80 [<Business: Sears>]

    81 

    82 # Queries across tables, involving primary key

    83 >>> Employee.objects.filter(business__name__exact='Sears')

    84 [<Employee: Dan Jones>, <Employee: Fran Jones>]

    85 >>> Employee.objects.filter(business__pk='Sears')

    86 [<Employee: Dan Jones>, <Employee: Fran Jones>]

    87 

    88 >>> Business.objects.filter(employees__employee_code__exact='ABC123')

    89 [<Business: Sears>]

    90 >>> Business.objects.filter(employees__pk='ABC123')

    91 [<Business: Sears>]

    92 >>> Business.objects.filter(employees__first_name__startswith='Fran')

    93 [<Business: Sears>]

    94 

    95 """}