Tracking dirty fields on a Django model instance
Project description
Tracking dirty fields on a Django model instance.
$ pip install django-dirtyfields
or if you’re interested in developing it
$ virtualenv --no-site-packages ve/ $ source ve/bin/activate (ve)$ pip install -r requirements.pip (ve)$ python setup.py develop (ve)$ cd example_app && ./manage.py test testing_app
Makes a Mixing available that will give you the methods:
is_dirty()
get_dirty_fields()
Using the Mixin in the Model
from django.db import models from dirtyfields import DirtyFieldsMixin class TestModel(DirtyFieldsMixin, models.Model): """A simple test model to test dirty fields mixin with""" boolean = models.BooleanField(default=True) characters = models.CharField(blank=True, max_length=80)
Using it in the shell
(ve)$ ./manage.py shell >>> from testing_app.models import TestModel >>> tm = TestModel(boolean=True,characters="testing") >>> tm.save() >>> tm.is_dirty() False >>> tm.get_dirty_fields() {} >>> tm.boolean = False >>> tm.is_dirty() True >>> tm.get_dirty_fields() {'boolean': True} >>> tm.characters = "have changed" >>> tm.is_dirty() True >>> tm.get_dirty_fields() {'boolean': True, 'characters': 'testing'} >>> tm.save() >>> tm.is_dirty() False >>> tm.get_dirty_fields() {} >>>
Checking foreign key fields.
By default, dirty functions are not checking foreign keys. If you want to also take these relationships into account, use check_relationship parameter:
(ve)$ ./manage.py shell >>> from testing_app.models import TestModel >>> tm = TestModel(fkey=obj1) >>> tm.save() >>> tm.is_dirty() False >>> tm.get_dirty_fields() {} >>> tm.fkey = obj2 >>> tm.is_dirty() False >>> tm.is_dirty(check_relationship=True) True >>> tm.get_dirty_fields() {} >>> tm.get_dirty_fields(check_relationship=True) {'fkey': obj1}
Why would you want this?
When using signals, especially pre_save, it is useful to be able to see what fields have changed or not. A signal could change its behaviour depending on whether a specific field has changed, whereas otherwise, you only could work on the event that the model’s save() method had been called.
Credits
This code has largely be adapted from what was made available at Stack Overflow.
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