I have a Django application that reads data from a web API and puts it in a database.
Is there a way to create a new object from a mode but prevent the duplicate exception if the object already exists?
In other words, is there a way to save an object, but to just do nothing if it already exists?
IntegrityError cause current transaction to abort and is not sufficient.
Jan 24, 2015 at 11:13
transaction.atomic (make sure you catch outside the atomic block, i.e. try: with acomic: create; except IntegrityError. It's also tricky to make sure you don't catch other integrity errors than the one you intend to
IntegrityError, my testing shows that it cuts the execution time nearly in half when the record exists compared to get_or_create().
In Django 1.7, you can also do:
It can be achieved using Model.objects.get_or_create()
Example
obj, created = Person.objects.get_or_create(
first_name='John',
last_name='Lennon',
defaults={'birthday': date(1940, 10, 9)},
)
Any keyword arguments(here first_name and last_name) passed to get_or_create() — except an optional one called defaults — will be used to query in database(find the object) in database.
It returns a tuple, if an object is found, get_or_create() returns a tuple of that object and False.
Note: Same thing can also be achieved using try except statements
Example:
try:
obj = Person.objects.get(first_name='John', last_name='Lennon')
except Person.DoesNotExist:
obj = Person(first_name='John', last_name='Lennon', birthday=date(1940, 10, 9))
obj.save()
Looks like in newer versions of Django the save() function does an UPDATE or INSERT by default. See here.
