===== DJANGO-REVERSION =====

==== Low-level API ====

Please refer to [[http://django-reversion.readthedocs.org/en/latest/api.html|django-reversion low level API v 1.8]]

It is valid for lower versions too.


==== Switch from "django-pro-history" to "django-reversion" ====

The steps to follow are:

  - delete fields django-pro-history fields from the models, where they are present;
  - register the models from the previous step to django-reversion;
  - create initial revisions for the registered models;
  - use django-pro-history methods instead of django-reversion methods in "base" models API;
  - migrate registred models with South to remove django-pro-history fields from the db;

The final results to check are:

  - it is possible to obtain programmaticly the different versions of an objects;
  - it is possible to obtain programmaticly the different versions of an objects for a certain time interval;
  - the models do not have django-pro-history fields anymore and are registered to django-reversion;
  - django-reversion added to the base requirements;
  - history fields "eradicated" from db;
  - it is possible to install GF including django-reversion;
  - it is possible to upgrade GF with django-reversion through an automatic script.

=== Delete fields django-pro-history fields from the models, where they are present ===

"history" fields removed from the models:

  * gas/models/order.py
    * GASSupplierOrder
    * GASSupplierOrderProduct
    * GASMemberOrder
    * Delivery
    * Withdrawal
  * supplier/models.py
    * Supplier
    * SupplierAgent
    * Certification
    * ProductCategory
    * ProductMU
    * ProductPU
    * Product
    * SupplierStock
  * base/models.py
    * Person
    * Contact
    * Place
    * DefaultTransition
  * gas/models/base.py
    * GAS
    * GASConfig
    * GASActivist
    * GASMember
    * GASSupplierStock
    * GASSupplierSolidalPact

=== Register the models from the previous step to django-reversion ===

For each of the model in the previous step, add:

<code>
import reversion 
.
.
.
class MyModel():
    .
    .
    .
    
if not reversion.is_registered(MyModel):
    reversion.register(MyModel)
</code>

=== Create initial revisions for the registered models ===

Exec:

<code>
django-admin.py createinitialrevisions [app[.model]] [-v {0,1,2,3}]
</code>

=== Use django-pro-history methods instead of django-reversion methods in "base" models API ===


=== Migrate registred models with South to remove django-pro-history fields from the db ===


==== Django-reversion low level API ====

It is possible to use django-reversion to retrieve information from the saved objects versions.

To produce versions from an object updates, django-reversion has to be instructed accordingly.

The easiest way is to register the model to the reversion.middleware.RevisionMiddleware. 

> NOTE: django-reversion version 1.5.7 does not save the User for the incoming requests into the revision. 
> If you want to have this facility, please use [[https://github.com/befair/django-reversion/tree/release-1.5.7-middleware-with-user | beFair version]] based on version 1.5.7 .

From then, it is possible to retrieve versions and info from an object.

=== All object revisions ===

<code>
import reversion

from app.models import mymodel

obj = mymodel.objects.get(pk=1)

reversion.get_for_object(obj)
</code> 

=== Object revisions for a time interval ===

<code>
import reversion

from app.models import mymodel

obj = mymodel.objects.get(pk=1)

reversion.get_for_object(obj).filter(revision__date_created__gt=datetime.datetime(y, m, d), revision__date_created__lt=datetime.datetime(y1, m1, d1))
</code>