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			91 lines
		
	
	
		
			2.5 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
			
		
		
	
	
			91 lines
		
	
	
		
			2.5 KiB
		
	
	
	
		
			Python
		
	
	
	
	
	
| """
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| 14. Using a custom primary key
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| 
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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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| 
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| from django.db import models
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| 
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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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|     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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| 
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|     def __repr__(self):
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|         return "%s %s" % (self.first_name, self.last_name)
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| 
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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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| 
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|     def __repr__(self):
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|         return self.name
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| 
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| 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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| [Dan Jones]
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| 
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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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| [Fran Bones, Dan Jones]
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| 
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| >>> Employee.objects.get(pk='ABC123')
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| Dan Jones
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| >>> Employee.objects.get(pk='XYZ456')
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| 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 does not exist for {'pk': 'foo'}
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| 
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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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| Dan Jones
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| 
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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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| [Dan Jones, Fran Jones]
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| >>> Employee.objects.in_bulk(['ABC123', 'XYZ456'])
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| {'XYZ456': Fran Jones, 'ABC123': Dan Jones}
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| 
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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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| [Dan Jones, Fran Jones]
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| >>> fran.business_set.all()
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| [Sears]
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| >>> Business.objects.in_bulk(['Sears'])
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| {'Sears': Sears}
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| 
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| >>> Business.objects.filter(name__exact='Sears')
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| [Sears]
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| >>> Business.objects.filter(pk='Sears')
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| [Sears]
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| 
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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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| [Dan Jones, Fran Jones]
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| >>> Employee.objects.filter(business__pk='Sears')
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| [Dan Jones, Fran Jones]
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| 
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| >>> Business.objects.filter(employees__employee_code__exact='ABC123')
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| [Sears]
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| >>> Business.objects.filter(employees__pk='ABC123')
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| [Sears]
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| >>> Business.objects.filter(employees__first_name__startswith='Fran')
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| [Sears]
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| 
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| """
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