Fix admin on group/user permissions

[BrendaH]

Addresses issue #126

Add a setting to make the used widget for selecting user/group for permissions customizeable and take into account the right to actually change user/group-permissions on forums.

No tests yet

NOTE: There are no tests yet for this code because I have not been able to get a test environment running on my windows machine and writing tests without being able to run them seemed like a bad idea. So if anybody is able to do this: please feel free.
I did of course run this code locally and thereby tested it and will probably try (again..) in the future to get a test environment running.

Meanwhile: feel free to test and comment or suggest improvements.

My use case

I'm already using the new setting locally like this:

settings.py:

MACHINA_FORUM_PERMISSIONS_USER_SELECT_WIDGET_FUNC = 'pe.widgets.machina_select_user_widget'
MACHINA_FORUM_PERMISSIONS_GROUP_SELECT_WIDGET_FUNC = 'pe.widgets.machina_select_group_widget'

pe.widgets.py:

def machina_select_user_widget(field, admin_site, **kwargs):
	"""
	Differs from the function below in that we want to display the whole name
	and not just the username which is the default string representation.
	"""
	# For a normal select:
	qset = field.related_model.objects.filter(is_active=True).order_by('first_name', 'last_name')
	choices = [(None, _('----'))]
	for obj in qset:
		choices.append((obj.id, obj.get_full_name()))
	return Select(choices=choices)

def machina_select_group_widget(field, admin_site, **kwargs):
	"""
	Differs from the function above this one in that it does not need to do
	difficult things to the string representation of the object.
	"""
	# For a normal select:
	qset = field.related_model.objects.all()
	choices = [(None, _('----'))]
	for obj in qset:
		choices.append((obj.id, str(obj)))
	return Select(choices=choices)

For me this creates a pulldown (select) for both users and groups without the need to have change permissions on groups/users. And I can even display the full names of the users instead of the default user name that a Select would normally show.

I have about 230 users in my project of which 170 are active, this gives me no noticeable overhead.

[BrendaH]

I was finally able to put up a test environment* and write tests for this improvement.

If there's an objection against these changes, please let me know. Else I'd like to see this PR merged. :-)

[*] Trouble on my windows machine was that colorama was required but not installed because the Pipfile.lock does not list it (Linux doesn't need it) and any errors about it were eaten by pluggy. (pytest-dev/pluggy#174)

[ellmetha]

Thanks for taking the time to submit this PR.

While I agree that the issue described in #126 should be addressed (the fact that user/group permissions related to forum_permission should be taken into account in the forum permissions page), I do not agree with the general approach of this PR. IMHO django-machina already provides a convenient way to lazy load classes or functions (through the use of the get_class helper). I don't see the need to create a new helper such as _get_setting_callable when you can make use of get_class to dynamically import the form classes used in the permission view. Of course these forms are now in the machina.forum.admin module but you could create a new machina.forum.forms module, put the considered forms in there and then import them in the admin module using get_class. By doing so we wouldn't have to add two new settings and you could still easily change the widgets of the permissions forms by making use of the machina's dynamic class-loading system.

What do you think?

[BrendaH]

Might be a good idea. Would've liked to know this earlier though, since at this moment I have lots of other work to do and will not be able for a while to work on this while earlier on I put quite some time in getting the tests (and test environment) for these changes going. Time better spent in redoing the whole thing the Machina-way, had I known. :-(

So yeah, I understand not merging this PR, but for now I can not work on it.
Anybody else is free to have a go at it. :-)

[ellmetha]

Closing. 660b34a introduces a change that allows to rely on the class loading mechanism to easily override forum permission forms (including fields and widgets).