A Django App for preserving revisions of modified Model Objects
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chronicler
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README.md

Chronicler

A Django App for preserving revisions of modified Model Objects

Advantages

There are already a number of revisioning applications for Django out there, but all of them have various limitations. The goal of chronicler was to handle tracking changes to many-to-many relations on a model in a more manageable manner.

The primary way that chronicler works is by inspecting the information coming into a view, grabbing a stale object, letting the view process, and then comparing the stale object to the newly created one. This is made easiest by the decorator supplied by the package. Please see the Usage section for more information on how it works.

Installation

To install via pip:

pip install chronicler

Or to grab the latest from source:

pip install -e git+git://github.com/analytehealth/chronicler.git#egg=chronicler

To install manually, clone the repository and run:

python setup.py install

After the package is installed, you'll want to add 'chronicler' to your INSTALLED_APPS in your Django project's settings. From there, you'll want to run syncdb or if you're using South you'll want to run migrations.

Usage

The primary method of usage for this tool is to leverage the decorator on views where the Model you wish to track will change. If you had a view that accepts POSTs to a form to change your model, you could use it like so:

from chronicler.decorators import audits

@audits(YourModel, ['relation_set', 'another_set'], 'pk', 'incoming_pk', 'POST')
def your_update_view(request):
    # modifications

The first arg to the decorator is the model that we're tracking changes on. The second argument is the list of relations we need to traverse in tracking any incoming changes. The third argument is the field we should use to look up the existing object by, and the fourth is the key we should inspect in the incoming GET/POST data for the value we use to look up our object. Finally, the last argument dictates if we should look in GET or POST for our data. Optionally, you can pass "force=True" to the decorator to create an audit trail everytime this view is properly processed. This disables the check chronicler makes to ensure there are actually differences between old and new.

After the view is processed properly, you should end up with a new AuditItem object in your database:

from chronicler.models import AuditItem
audit_item = AuditItem.objects.filter(content_object=your_object).latest()

AuditItems have a @property of audit_data. That returns a JSON representation of the data at the time the snapshot was taken. Inside there you'll find your historical data and can use it as you wish.