update_or_create(defaults=None, **kwargs)
A convenience method for updating an object with the given kwargs, creating a new one if necessary. The defaults is a dictionary of (field, value) pairs used to update the object.
Returns a tuple of (object, created), where object is the created or updated object and created is a boolean specifying whether a new object was created.
The update_or_create method tries to fetch an object from database based on the given kwargs. If a match is found, it updates the fields passed in the defaults dictionary.
This is meant as a shortcut to boilerplatish code. For example:
1 2 3 4 5 6 7 8 9 | try: obj = Person.objects.get(first_name='John', last_name='Lennon') for key, value in updated_values.iteritems(): setattr(obj, key, value) obj.save()except Person.DoesNotExist: updated_values.update({'first_name': 'John', 'last_name': 'Lennon'}) obj = Person(**updated_values) obj.save() |
This pattern gets quite unwieldy as the number of fields in a model goes up. The above example can be rewritten using update_or_create() like so:
1 2 | obj, created = Person.objects.update_or_create( first_name='John', last_name='Lennon', defaults=updated_values) |
For detailed description how names passed in kwargs are resolved see get_or_create().
As described above in get_or_create(), this method is prone to a race-condition which can result in multiple rows being inserted simultaneously if uniqueness is not enforced at the database level.
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