I don't undestand how to use django-reversion

[alekam]

Hi all.

In my project some users can make changes in one model and I want to
use django-reversion to audit trail some fields (not all) in this
model. Some another fields in this model can be changed by signals and
this fields is not valuable for me - its need to improve admin area
and make my project run more faster. I try to use django-reversion and
see that it save model data after each its post_save signal. if
unmonitored fields is changed, I expect that model data revision is
not created.

Please look at example:

# ~model.py~ ##################################################
from django.db import models
import reversion

class Author(models.Model):
full_name = models.CharField(max_length=65)
articles = models.PositiveSmallIntegerField(blank=True, default=0)

def __unicode__(self):
return self.full_name

class Article(models.Model):
title = models.CharField(max_length=255)
body = models.TextField()
author = models.ForeignKey(Author)

if not reversion.is_registered(Author):
reversion.register(Author, fields=['pk', 'full_name'])

def save_article(sender, instance, created, **kwargs):
if created:
a = instance.author
a.articles += 1
a.save()

def delete_article(sender, instance, **kwargs):
a = instance.author
a.articles -= 1
a.save()

models.signals.post_save.connect(save_article, Article,
dispatch_uid="article.post_save")
models.signals.post_delete.connect(delete_article, Article,
dispatch_uid="article.post_delete")

###########################################################
#~tests.py~

__test__ = {"doctest": """
>>> from models import Author, Article
>>> import reversion
>>> from reversion.models import Version

Creating object - 1st rev.

>>> with reversion.revision:
... a = Author.objects.create(full_name='John Dou')
...
>>> Version.objects.get_for_object(a)
[<Version: John Dou>]

Change object - 2nd rev.

>>> with reversion.revision:
... a.title = 'John Smith'
... a.save()
>>> a = Author.objects.get(pk=a.id)
>>> versions = Version.objects.get_for_object(a)
>>> versions
[<Version: John Dou>, <Version: John Smith>]
>>> versions[0].field_dict
{'id': 1, 'full_name': u'John Dou'}
>>> versions[1].field_dict
{'id': 1, 'full_name': u'John Smith'}

Change unwatched field via signal - 2nd rev. still

>>> a.articles
0
>>> with reversion.revision:
... art = Article.objects.create(title="1st article", body="1st
article body", author=a)
...
>>> a.articles
1
>>> a = Author.objects.get(pk=a.id)
>>> versions = Version.objects.get_for_object(a)
>>> versions
[<Version: John Dou>, <Version: John Smith>]

"""}

###############################################################
# ~ tests.log~

======================================================================
FAIL: Doctest: unwatched_fields.tests.__test__.doctest
----------------------------------------------------------------------
Failed example:
versions
Expected:
[<Version: John Dou>, <Version: John Smith>]
Got:
[<Version: John Dou>, <Version: John Dou>]
----------------------------------------------------------------------
Failed example:
versions[0].field_dict
Expected:
{'id': 1, 'full_name': u'John Dou'}
Got:
{'articles': 0, 'id': 1, 'full_name': u'John Dou'}
----------------------------------------------------------------------
Failed example:
versions[1].field_dict
Expected:
{'id': 1, 'full_name': u'John Smith'}
Got:
{'articles': 0, 'id': 1, 'full_name': u'John Dou'}
----------------------------------------------------------------------
Failed example:
versions
Expected:
[<Version: John Dou>, <Version: John Smith>]
Got:
[<Version: John Dou>, <Version: John Dou>, <Version: John Dou>]

----------------------------------------------------------------------
Ran 1 test in 0.052s

FAILED (failures=1)

#########################################################

It was tested with with django 1.1.1 and trunk rev.11778, django-
reversion 1.2 and
trunk rev. 263 from http://django-reversion.googlecode.com/svn/trunk/src

I think I don't understand smth. (

[David Hall]

Hi,

The current behaviour is to save a new revision each time a model is saved, regardless of whether the model has actually changed or not.

Changing this behaviour would slow down the site slightly, and increase memory usage slightly. It would, however, potentially save disk space and database queries.

I'd like to hear other people's views on whether the current behaviour should be changed. My personal preference is for the current behaviour, as it's simpler and works better with people's expectations in the admin system.

Best wishes,

Dave.

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Etianen.com

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