[Django] Database transactions

Today I found that Django database transactions feature may be very useful in some applications:

change/add many records in one place of code
skip changes on exception
add all records or nothing - atomic behavior

Example:

# this code produces 100 requests to database
from .models import MyModel


def my_view(request):
    for i in range(100):
        m = MyModel(number=i)
        m.save()

# this code produces only 1 request to database
from django.db import transaction

from .models import MyModel

@transaction.commit_on_success
def my_view(request):
    for i in range(100):
        m = MyModel(number=i)
        m.save()

# this will add only one record to database
from .models import MyModel

def my_view(request):
    for i in range(100):
        m = MyModel(number=i)
        m.save()
        raise Exception('Some error')

# this will add no records to database
from django.db import transaction

from .models import MyModel

@transaction.commit_on_success
def my_view(request):
    for i in range(100):
        m = MyModel(number=i)
        m.save()
        raise Exception('Some error')

See more examples in the documentation.

My fail: It appears that MySQL MyISAM does not support transcations (or, maybe this feature should be enable somehow, anyway, seems like InnoDB is a better choice).

If You use MySQL, enable InnoDB:

DATABASES = {
    'default': {
    'ENGINE': 'django.db.backends.mysql',
        ...
        'OPTIONS': {
            'init_command': 'SET storage_engine=INNODB',
        },
    }
}

Links:

https://docs.djangoproject.com/en/1.5/topics/db/transactions/

Licensed under CC BY-SA 3.0