FormPreview should pass request to parse_params

[Bob Thomas]

It would be very useful to have request data in parse_params. The example given is to capture something like a user_id, but the main thing I would want to do here is to verify that the current user has permission to access the URL given. Of course, adding a parameter breaks backwards compatibility, so this is a similar request to #7222.

[Bob Thomas]

Add request parameter to parse_params

[Bob Thomas]

Forgot to mention, FormWizard's version of parse_params includes the request parameter.

[Jacob]

This unfortunately introduces a subtle backwards-incompatibility: if parse_params is defined in the old way (parse_params(*args, **kw)), then args[0] will become request with this patch, thereby breaking user code. So we need to make sure this is really a vital change before we make that change.

[Bob Thomas]

I'm aware of the incompatibility (I mentioned it in the description), and it is unfortunate. We could define a new function like parse_request_params that passes request as the first argument (and calls parse_params without it), but I think that's a bit ugly.

This will only affect users that:

1. Are overriding parse_params
   
2. Are using unnamed args
   

Personally, I only use named arguments in URLconfs, but I can't speak for the rest of the community.

[Ramiro Morales]

Patch that tries to provide backwards compatibility. No tests and no docs yet, they can be added if idea isn't deeemed wrong

[Bob Thomas]

This works for me. Should we also add a DeprecationWarning for users who define parse_params the old way? Something like:

            import warnings
            warnings.warn(
                message = "Defining parse_params without the request parameter is deprecated. Define it as parse_params(self, request, *args, **kwargs) instead.",
                category = DeprecationWarning,
                stacklevel = 2
            )

[Aymeric Augustin]

Change UI/UX from NULL to False.

[Aymeric Augustin]

Change Easy pickings from NULL to False.

[Greg Chapple]

formtools has been extracted into its own repository (​​​​https://github.com/django/django-formtools/). Because of this, the issue tracking for this package has been moved to GitHub issues. I'm going to close this ticket, but I've created a GitHub issue to replace it where the conversation can continue: ​​​​https://github.com/django/django-formtools/issues/22. Thanks!