Django documentation

33. get_or_create()

This example is for Django's SVN release, which can be significantly different from previous releases. Get old examples here: 0.96, 0.95.

get_or_create() does what it says: it tries to look up an object with the given parameters. If an object isn’t found, it creates one with the given parameters.

Model source code

from django.db import models, IntegrityError

class Person(models.Model):
    first_name = models.CharField(max_length=100)
    last_name = models.CharField(max_length=100)
    birthday = models.DateField()

    def __unicode__(self):
        return u'%s %s' % (self.first_name, self.last_name)

Sample API usage

This sample code assumes the above model has been saved in a file mysite/models.py. 

>>> from mysite.models import Person

# Acting as a divine being, create an Person.
>>> from datetime import date
>>> p = Person(first_name='John', last_name='Lennon', birthday=date(1940, 10, 9))
>>> p.save()

# Only one Person is in the database at this point.
>>> Person.objects.count()
1

# get_or_create() a person with similar first names.
>>> p, created = Person.objects.get_or_create(first_name='John', last_name='Lennon', defaults={'birthday': date(1940, 10, 9)})

# get_or_create() didn't have to create an object.
>>> created
False

# There's still only one Person in the database.
>>> Person.objects.count()
1

# get_or_create() a Person with a different name.
>>> p, created = Person.objects.get_or_create(first_name='George', last_name='Harrison', defaults={'birthday': date(1943, 2, 25)})
>>> created
True
>>> Person.objects.count()
2

# If we execute the exact same statement, it won't create a Person.
>>> p, created = Person.objects.get_or_create(first_name='George', last_name='Harrison', defaults={'birthday': date(1943, 2, 25)})
>>> created
False
>>> Person.objects.count()
2

# If you don't specify a value or default value for all required fields, you
# will get an error.
>>> try:
...     p, created = Person.objects.get_or_create(first_name='Tom', last_name='Smith')
... except Exception, e:
...     if isinstance(e, IntegrityError):
...         print "Pass"
...     else:
...         print "Fail with %s" % type(e)
Pass

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