Revisions

We use django-reversion for creating revisions and versions.

How django-reversion works

django-reversion uses revisions and versions.

Revisions are blocks of code where some changes happen. One or more objects could potentially change in the same block.

Versions are changes to an object in a given revision. Versions always have a foreign key to the related revision.

Revisions can have the following metadata:

• user: who made the changes
• comment: optional text

Metadata has to be set manually for obvious reasons.

Usually you implement django-reversion in various ways:

• via the admin integration so that every time a user uses the admin, changes are saved automatically
• via an explicit context manager with the possibility to set metadata programmatically

How django-reversion is used

As we wanted to create revisions/versions automatically and not lose any changes, we implemented django-reversion at a lower level.

In our system we have 2 types of changes:

• CDMS refresh changes: where we refresh a local object (update or create) from CDMS. This happens automatically by creating a version of the object with the comment CDMS refresh.
• local changes: where we make a change to the objects of our system. This happens every time the .save() method is called and it’s automatic.

Note

As we can’t access the user automatically, we are currently not setting the related metadata on the revision. We need to look into this, it might just be a matter of using the context manager in API views.