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92 lines
2.8 KiB
Python
92 lines
2.8 KiB
Python
"""
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14. Using a custom primary key
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By default, Django adds an ``"id"`` field to each model. But you can override
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this behavior by explicitly adding ``primary_key=True`` to a field.
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"""
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from django.db import models
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class Employee(models.Model):
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employee_code = models.CharField(maxlength=10, primary_key=True,
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db_column = 'code')
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first_name = models.CharField(maxlength=20)
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last_name = models.CharField(maxlength=20)
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class Meta:
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ordering = ('last_name', 'first_name')
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def __str__(self):
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return "%s %s" % (self.first_name, self.last_name)
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class Business(models.Model):
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name = models.CharField(maxlength=20, primary_key=True)
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employees = models.ManyToManyField(Employee)
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class Meta:
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verbose_name_plural = 'businesses'
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def __str__(self):
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return self.name
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__test__ = {'API_TESTS':"""
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>>> dan = Employee(employee_code='ABC123', first_name='Dan', last_name='Jones')
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>>> dan.save()
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>>> Employee.objects.all()
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[<Employee: Dan Jones>]
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>>> fran = Employee(employee_code='XYZ456', first_name='Fran', last_name='Bones')
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>>> fran.save()
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>>> Employee.objects.all()
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[<Employee: Fran Bones>, <Employee: Dan Jones>]
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>>> Employee.objects.get(pk='ABC123')
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<Employee: Dan Jones>
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>>> Employee.objects.get(pk='XYZ456')
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<Employee: Fran Bones>
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>>> Employee.objects.get(pk='foo')
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Traceback (most recent call last):
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...
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DoesNotExist: Employee matching query does not exist.
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# Use the name of the primary key, rather than pk.
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>>> Employee.objects.get(employee_code__exact='ABC123')
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<Employee: Dan Jones>
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# Fran got married and changed her last name.
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>>> fran = Employee.objects.get(pk='XYZ456')
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>>> fran.last_name = 'Jones'
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>>> fran.save()
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>>> Employee.objects.filter(last_name__exact='Jones')
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[<Employee: Dan Jones>, <Employee: Fran Jones>]
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>>> Employee.objects.in_bulk(['ABC123', 'XYZ456'])
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{'XYZ456': <Employee: Fran Jones>, 'ABC123': <Employee: Dan Jones>}
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>>> b = Business(name='Sears')
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>>> b.save()
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>>> b.employees.add(dan, fran)
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>>> b.employees.all()
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[<Employee: Dan Jones>, <Employee: Fran Jones>]
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>>> fran.business_set.all()
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[<Business: Sears>]
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>>> Business.objects.in_bulk(['Sears'])
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{'Sears': <Business: Sears>}
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>>> Business.objects.filter(name__exact='Sears')
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[<Business: Sears>]
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>>> Business.objects.filter(pk='Sears')
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[<Business: Sears>]
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# Queries across tables, involving primary key
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>>> Employee.objects.filter(business__name__exact='Sears')
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[<Employee: Dan Jones>, <Employee: Fran Jones>]
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>>> Employee.objects.filter(business__pk='Sears')
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[<Employee: Dan Jones>, <Employee: Fran Jones>]
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>>> Business.objects.filter(employees__employee_code__exact='ABC123')
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[<Business: Sears>]
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>>> Business.objects.filter(employees__pk='ABC123')
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[<Business: Sears>]
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>>> Business.objects.filter(employees__first_name__startswith='Fran')
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[<Business: Sears>]
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"""}
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