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model/field instance creation. Based on a patch from Richard Davies. git-svn-id: http://code.djangoproject.com/svn/django/trunk@8884 bcc190cf-cafb-0310-a4f2-bffc1f526a37
148 lines
4.5 KiB
Python
148 lines
4.5 KiB
Python
# -*- coding: utf-8 -*-
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"""
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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.conf import settings
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from django.db import models, transaction, IntegrityError
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class Employee(models.Model):
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employee_code = models.IntegerField(primary_key=True, db_column = 'code')
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first_name = models.CharField(max_length=20)
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last_name = models.CharField(max_length=20)
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class Meta:
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ordering = ('last_name', 'first_name')
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def __unicode__(self):
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return u"%s %s" % (self.first_name, self.last_name)
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class Business(models.Model):
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name = models.CharField(max_length=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 __unicode__(self):
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return self.name
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__test__ = {'API_TESTS':"""
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>>> dan = Employee(employee_code=123, 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=456, 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=123)
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<Employee: Dan Jones>
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>>> Employee.objects.get(pk=456)
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<Employee: Fran Bones>
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>>> Employee.objects.get(pk=42)
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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=123)
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<Employee: Dan Jones>
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# pk can be used as a substitute for the primary key.
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>>> Employee.objects.filter(pk__in=[123, 456])
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[<Employee: Fran Bones>, <Employee: Dan Jones>]
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# The primary key can be accessed via the pk property on the model.
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>>> e = Employee.objects.get(pk=123)
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>>> e.pk
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123
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# Or we can use the real attribute name for the primary key:
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>>> e.employee_code
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123
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# Fran got married and changed her last name.
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>>> fran = Employee.objects.get(pk=456)
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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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>>> emps = Employee.objects.in_bulk([123, 456])
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>>> emps[123]
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<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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{u'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=123)
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[<Business: Sears>]
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>>> Business.objects.filter(employees__pk=123)
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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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# Primary key may be unicode string
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>>> bus = Business(name=u'jaźń')
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>>> bus.save()
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# The primary key must also obviously be unique, so trying to create a new
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# object with the same primary key will fail.
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>>> try:
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... sid = transaction.savepoint()
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... Employee.objects.create(employee_code=123, first_name='Fred', last_name='Jones')
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... transaction.savepoint_commit(sid)
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... except Exception, e:
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... if isinstance(e, IntegrityError):
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... transaction.savepoint_rollback(sid)
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... print "Pass"
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... else:
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... print "Fail with %s" % type(e)
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Pass
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"""}
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# SQLite lets objects be saved with an empty primary key, even though an
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# integer is expected. So we can't check for an error being raised in that case
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# for SQLite. Remove it from the suite for this next bit.
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if settings.DATABASE_ENGINE != 'sqlite3':
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__test__["API_TESTS"] += """
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# The primary key must be specified, so an error is raised if you try to create
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# an object without it.
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>>> try:
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... sid = transaction.savepoint()
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... Employee.objects.create(first_name='Tom', last_name='Smith')
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... print 'hello'
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... transaction.savepoint_commit(sid)
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... print 'hello2'
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... except Exception, e:
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... if isinstance(e, IntegrityError):
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... transaction.savepoint_rollback(sid)
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... print "Pass"
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... else:
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... print "Fail with %s" % type(e)
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Pass
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"""
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