django-reversion-compare is an extension to django-reversion that provides a history compare view to compare two versions of a model which is under reversion.

Comparing model versions is not a easy task. Maybe there are different view how this should looks like. This project will gives you a generic way to see whats has been changed.

Many parts are customizable by overwrite methods or subclassing, see above.

	coveralls.io/r/jedie/django-reversion-compare
	travis-ci.org/jedie/django-reversion-compare
	requires.io/github/jedie/django-reversion-compare/requirements/

Just use:

pip install django-reversion-compare

Optionally you can install google-diff-match-patch, otherwise difflib would be used. The easiest way is to use the unofficial package diff-match-patch, e.g.:

pip install diff-match-patch

Add reversion_compare to INSTALLED_APPS in your settings.py, e.g.:

INSTALLED_APPS = (
    'django...',
    ...
    'reversion', # https://github.com/etianen/django-reversion
    'reversion_compare', # https://github.com/jedie/django-reversion-compare
    ...
)

# Add reversion models to admin interface:
ADD_REVERSION_ADMIN=True

Inherit from CompareVersionAdmin instead of VersionAdmin to get the comparison feature.

admin.py e.g.:

from django.contrib import admin
from reversion_compare.admin import CompareVersionAdmin

from my_app.models import ExampleModel

class ExampleModelAdmin(CompareVersionAdmin):
    pass

admin.site.register(ExampleModel, ExampleModelAdmin)

If you're using an existing third party app, then you can add patch django-reversion-compare into its admin class by using the reversion_compare.helpers.patch_admin() method. For example, to add version control to the built-in User model:

from reversion_compare.helpers import patch_admin

patch_admin(User)

e.g.: Add django-cms Page model:

from cms.models.pagemodel import Page
from reversion_compare.helpers import patch_admin


# Patch django-cms Page Model to add reversion-compare functionality:
patch_admin(Page)

It's possible to change the look for every field or for a entire field type. You must only define a methods to your admin class with this name scheme:

• "compare_%s" % field_name
• "compare_%s" % field.get_internal_type()

If there is no method with this name scheme, the fallback_compare() method will be used.

An example for specifying a compare method for a model field by name:

class YourAdmin(CompareVersionAdmin):
    def compare_foo_bar(self, obj_compare):
        """ compare the foo_bar model field """
        return "%r <-> %r" % (obj_compare.value1, obj_compare.value2)

and example using patch_admin with custom version admin class:

patch_admin(User, AdminClass=YourAdmin)

Beyond the Admin views, you can also create a Class Based View for displaying and comparing version differences. This is a single class-based-view that either displays the list of versions to select for an object or displays both the versions and their differences (if the versions to be compared have been selected). This class can be used just like a normal DetailView:

Inherit from it in your class and add a model (or queryset), for example:

from reversion_compare.views import HistoryCompareDetailView

class SimpleModelHistoryCompareView(HistoryCompareDetailView):
    model = SimpleModel

Then, assign that CBV to a url, for example:

url(r'^test_view/(?P<pk>\d+)$', views.SimpleModelHistoryCompareView.as_view() ),

Last step, you need to create a template to display both the version select form and the changes part (if the form is submitted). An example template is the following:

<style type="text/css">
/* minimal style for the diffs */
del, ins {
    color: #000;
    text-decoration: none;
}
del { background-color: #ffe6e6; }
ins { background-color: #e6ffe6; }
sup.follow { color: #5555ff; }
</style>

{% include "reversion-compare/action_list_partial.html"  %}
{% if request.GET.version_id1 %}
    {% include "reversion-compare/compare_partial.html"  %}
    {% include "reversion-compare/compare_links_partial.html"  %}
{% endif %}

Beyond the styling, you should include:

• reversion-compare/action_list_partial.html partial template to display the version select form
• reversion-compare/compare_partial.html partial template to display the actual version
• reversion-compare/compare_links_partial.html to include previous/next comparison links

compare_partial.html and compare_links_partial.html will show the compare-related information so it's better to display them only when the select-versions-tocompare-form has been submitted. If you want more control on the appearence of your templates you can check the above partials to understand how the availabble context variables are used and override them completely.

Here some screenshots of django-reversion-compare:

How to select the versions to compare:

from v0.1.0: DateTimeField compare (last update), TextField compare (content) with small changes and a ForeignKey compare (child model instance was added):

from v0.1.0: Same as above, but the are more lines changed in TextField and the ForeignKey relation was removed:

Example screenshot from v0.3.0: a many-to-many field compare (friends, hobbies):

• In the first line, the m2m object has been changed.
• line 2: A m2m object was deleted
• line 3: A m2m object was removed from this entry (but not deleted)
• line 4: This m2m object has not changed

(Unittests need django-tools)

via setup.py:

$ cd path/to/django-reversion-compare
django-reversion-compare$ ./setup.py test

via runtests.py:

$ cd path/to/django-reversion-compare
django-reversion-compare$ ./runtests.py

Helpfull for writing and debugging unittests is to run a local test server with the same data. e.g.:

~$ cd path/to/django-reversion-compare/
/django-reversion-compare$ ./run_testserver.py

migration will be run and a superuser will be created. Username: test Password: 12345678

These are the unittests variants. See also: /.travis.yml Maybe other versions are compatible, too.

• v0.6.1 - 16.02.2016:
  • pull #61: Fix error when ManyToMany relations didn't exist contributed by Diederik van der Boor
• v0.6.0 - 03.02.2016:
  • Added Dutch translation contributed by Sae X
  • Add support for Django 1.9
  • Nicer boolean compare: #57
  • Fix #58 compare followed reverse foreign relation fields that are on a non-abstract parent class contributed by LegoStormtroopr
• v0.5.6 - 23.09.2015:
  • NEW: Class-Based-View to create non-admin views and greek translation contributed by Serafeim Papastefanos.
• v0.5.5 - 24.07.2015:
  • UnboundLocalError ('version') when creating deleted list in get_many_to_something() #41
• v0.5.4 - 22.07.2015:
  • One to one field custom related name fix #42 (contributed by frwickst and aemdy)
• v0.5.3 - 13.07.2015:
  • Update admin.py to avoid RemovedInDjango19Warning (contributed by luzfcb)
• v0.5.2 - 14.04.2015:
  • contributed by Samuel Spencer:
    • Added Django 1.8 support: pull #35
    • list of changes for reverse fields incorrectly includes a "deletion" for the item that was added in: issues #34
• v0.5.1 - 28.02.2015:
  • activate previous/next links and add unitests for them
• v0.5.0 - 27.02.2015:
  • refactory unittests, test with Django v1.7 and Python 2.7 & 3.4
• v0.4.0 - 02.02.2015:
  • Updates for django 1.7 support
  • Add settings.ADD_REVERSION_ADMIN
• v0.3.5 - 03.01.2013:
  • Remove date from version string. issues 9
• v0.3.4 - 20.06.2012:
  • Use VersionAdmin.revision_manager rather than default_revision_manager, contributed by Mark Lavin - see: pull request 7
  • Use logging for all debug prints, contributed by Bojan Mihelac - see: pull request 8
• v0.3.3 - 11.06.2012:
  • Bugfix "ValueError: zero length field name in format" with Python 2.6 issues 5
• v0.3.2 - 04.06.2012:
  • Bugfix for Python 2.6 in unified_diff(), see: AttributeError: 'module' object has no attribute '_format_range_unified'
• v0.3.1 - 01.06.2012:
  • Bugfix: force unicode in html diff
  • Bugfix in unittests
• v0.3.0 - 16.05.2012:
  • Enhanced handling of m2m changes with follow and non-follow relations.
• v0.2.2 - 15.05.2012:
  • Compare many-to-many in the right way.
• v0.2.1 - 10.05.2012:
  • Bugfix for models which has no m2m field: https://github.com/jedie/django-reversion-compare/commit/c8e042945a6e78e5540b6ae27666f9b0cfc94880
• v0.2.0 - 09.05.2012:
  • many-to-many compare works, too.
• v0.1.0 - 08.05.2012:
  • First release
• v0.0.1 - 08.05.2012:
  • collect all compare stuff from old "diff" branch
  • see also: etianen/django-reversion#147

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