Expand on "auxiliary" data like current request or user

[MoritzS]

I think we didn't explicitly mention how extra, non-ORM data should be handled.

On the construction step it says in the docs:

It should be easy to modify the set of fields on a per-request basis.

In "Existing Data" it also says:

This includes but is not limited to field defaults, initial data and model instances.

I still think we should explicitly document especially how the current request (and user) can be incorporated into the adapter since in my experience (reading #django) that is one the first things where new users get frustrated.

[mjtamlyn]

Agreed. In my opinion we should try to be explicit about context as well, rather than encouraging passing request - this makes testing more complex.