Implement import-export library

[se-bastiaan]

Describe the change

We could may be use https://django-import-export.readthedocs.io/en/latest/# for the importing (do we do that?) and exporting of information.

Motivation

We have a lot of duplicated csv exporting. And we have limited this to only what is necessary. With such a plugin exporting would become a breeze for all the data we have.

Current implementation

We have duplicated CSV exporting options everywhere.

Suggested implementation

Nice mixins.

Additional context

This issue should result in a new issue (possibly just change this one) that explains the benefits over just refactoring our current code. And if there are no benefits this issue is done and should be closed.

[JobDoesburg]

The only places where importing might be nice to have is:

• mentorships
• email groups (think of study-trip participants)
• possibly in the far future: payments
• courses
• pizza products

Exports might be nice at many places of course

[JobDoesburg]

I've used it in a couple of my own projects and it works really well

[JobDoesburg]

It appears to be more difficult than I thought upfront, because import-export-admins are only able to just import/export model fields. It is more complex if, for example, you want to include 'the email of the user of this event registration' or 'the number of registrations / cancellations for this event' in the export. It is not impossible, but it is quite complex as it requires you to redefine your models as resources.ModelResources. So it's not only an admin-side change

[se-bastiaan]

Let's close this, I don't really see us doing this if it is more complex than what we have already.

[JobDoesburg]

I don't really agree. I do think it is a nice thing to do, as defining ModelResources is not very hard to do and it does make your code really nicely readable.

[se-bastiaan]

This library is awesome, would really make it easier to do some things that we have built manually

[JobDoesburg]

I recently tried this out for a hobby project of mine and it works like a charm :) (at least, the exporting part. The importing part is a bit more tricky but luckily we don't use that)