Re: Right place to decrypt/decode data from DB before passing it to UI without affect data in DB itself.

Hi,

Le 8 févr. 2016 à 19:00, learn django <siddhesh.divekar@gmail.com> a écrit :

Hi,

I store some data like email text, headers and from email address in encoded format in the database.

I want to have a  page where I can display all this information in readonly format.

What is the ideal place & way to decode this information and pass it to django UI.

I was thinking of reading all the information in my views.py.

But then I don't want to affect my DB. aka information in DB should remain encoded.

eg.

class FooViewSet(viewsets.ModelViewSet):

    queryset = Message.objects.all()

Message object has headers, body and from fields which are encoded before storing in db.

If I perform any operation on queryset those changes will be reflected in DB so I cannot do that.

If I do something like below then I get exception for using list as queryset becomes a list object instead of queryset object.

class FooViewSet(viewsets.ModelViewSet):

    queryset = list(Message.objects.all())

    for obj in queryset:

        body = base64.b64decode(obj.body)

        obj.body = body

This wil not work for different reasons.

First one is about Python scope. Doing this will get you a fixed list of Message unless you restart the server.

Second is you're using a generic view that expects QuerySet as you've noticed. Overriding get_queryset would get somewhat bette result but it still wouldn't work as QuerySet are expected for pagination and filtering.

The best place to perform that are to_representation and to_internal_value for that field.

You should have a look at the custom fields (http://www.django-rest-framework.org/api-guide/fields/#custom-fields) for guidance about how to handle that.

Regards,

Xavier,

Linovia.