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83 lines
2.5 KiB
83 lines
2.5 KiB
""" |
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33. get_or_create() |
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``get_or_create()`` does what it says: it tries to look up an object with the |
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given parameters. If an object isn't found, it creates one with the given |
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parameters. |
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""" |
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from django.db import models, IntegrityError |
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class Person(models.Model): |
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first_name = models.CharField(max_length=100) |
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last_name = models.CharField(max_length=100) |
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birthday = models.DateField() |
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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 ManualPrimaryKeyTest(models.Model): |
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id = models.IntegerField(primary_key=True) |
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data = models.CharField(max_length=100) |
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__test__ = {'API_TESTS':""" |
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# Acting as a divine being, create an Person. |
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>>> from datetime import date |
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>>> p = Person(first_name='John', last_name='Lennon', birthday=date(1940, 10, 9)) |
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>>> p.save() |
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# Only one Person is in the database at this point. |
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>>> Person.objects.count() |
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1 |
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# get_or_create() a person with similar first names. |
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>>> p, created = Person.objects.get_or_create(first_name='John', last_name='Lennon', defaults={'birthday': date(1940, 10, 9)}) |
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# get_or_create() didn't have to create an object. |
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>>> created |
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False |
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# There's still only one Person in the database. |
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>>> Person.objects.count() |
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1 |
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# get_or_create() a Person with a different name. |
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>>> p, created = Person.objects.get_or_create(first_name='George', last_name='Harrison', defaults={'birthday': date(1943, 2, 25)}) |
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>>> created |
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True |
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>>> Person.objects.count() |
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2 |
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# If we execute the exact same statement, it won't create a Person. |
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>>> p, created = Person.objects.get_or_create(first_name='George', last_name='Harrison', defaults={'birthday': date(1943, 2, 25)}) |
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>>> created |
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False |
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>>> Person.objects.count() |
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2 |
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# If you don't specify a value or default value for all required fields, you |
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# will get an error. |
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>>> try: |
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... p, created = Person.objects.get_or_create(first_name='Tom', last_name='Smith') |
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... except Exception, e: |
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... if isinstance(e, IntegrityError): |
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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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# If you specify an existing primary key, but different other fields, then you |
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# will get an error and data will not be updated. |
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>>> m = ManualPrimaryKeyTest(id=1, data='Original') |
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>>> m.save() |
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>>> try: |
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... m, created = ManualPrimaryKeyTest.objects.get_or_create(id=1, data='Different') |
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... except Exception, e: |
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... if isinstance(e, IntegrityError): |
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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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>>> ManualPrimaryKeyTest.objects.get(id=1).data == 'Original' |
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True |
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"""}
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