Accessing attributes of the current view in Django middleware?

[alk...@gmail.com]

I'm trying to access an attribute of the current view instance in the middleware layer.

For example, given a class-based view like this:

# views.py
class MyView(View):
    my_attribute = 'something'

I'd love to be able to get a handle on my_attribute in the middleware by doing something like this:

# middleware.py
def process_view(self, request, view_func, view_args, view_kwargs):
    my_attribute = request.view.my_attribute

Of course, this does not work because Django doesn't expose the view instance through the request object.

Is there any way to get this accomplished?

Many thanks!

[Mario Gudelj]

Since the request is simply a dictionary, can you not append that attribute to it?

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[thinkin...@gmail.com]

Hey,

Try along these lines:

    def process_view(self, request, view_func, view_args, view_kwargs):

        view = get_class(view_func.__module__, view_func.__name__)

        view.my_attribute

While `get_class()`:

from django.utils import importlib

def get_class(module_name, cls_name):

    try:

        module = importlib.import_module(module_name)

    except ImportError:

        raise ImportError('Invalid class path: {}'.format(module_name))

    try:

        cls = getattr(module, cls_name)

    except AttributeError:

        raise ImportError('Invalid class name: {}'.format(cls_name))

    else:

        return cls

Robert

[alk]

Thanks a lot for the replies.

On Saturday, December 28, 2013 4:46:18 AM UTC-5, somecallitblues wrote:

Since the request is simply a dictionary, can you not append that attribute to it?

The view hasn't been called yet at that point in the middleware stack, so I don't think it would have had an opportunity to modify the request dictionary:

https://docs.djangoproject.com/en/1.6/topics/http/middleware/#hooks-and-application-order

But I think your suggestion would probably work great to grab the attribute in the `process_response()` or `process_template_response()` middleware hooks.

On Saturday, December 28, 2013 8:19:22 AM UTC-5, thinkin...@gmail.com wrote:

Hey,

Try along these lines:

    def process_view(self, request, view_func, view_args, view_kwargs):

        view = get_class(view_func.__module__, view_func.__name__)

        view.my_attribute

Heh, yeah, this seems to be the only way.  I was kind of headed in this direction but I'm fairly new to Django/python, and to programming in general.  Is this safe/efficient?  I guess this just involves importing the view class once per request -- doesn't seem like a big deal but would love some feedback.

Thanks again!

[thinkin...@gmail.com]

On Saturday, December 28, 2013 6:44:16 PM UTC, alk wrote:

On Saturday, December 28, 2013 8:19:22 AM UTC-5, thinkin...@gmail.com wrote:

Hey,

Try along these lines:

    def process_view(self, request, view_func, view_args, view_kwargs):

        view = get_class(view_func.__module__, view_func.__name__)

        view.my_attribute

Heh, yeah, this seems to be the only way.  I was kind of headed in this direction but I'm fairly new to Django/python, and to programming in general.  Is this safe/efficient?  I guess this just involves importing the view class once per request -- doesn't seem like a big deal but would love some feedback.

Thanks again!

Is it safe: well, as far as I can tell there is no reason it should not be. In terms of efficiency, it's always a little bit an overhead to every request, no matter you need it or not. Have a look at this code:

https://github.com/thinkingpotato/django-permissionsx/blob/v0.0.6/permissionsx/middleware.py

There's some caching done etc. And it's been tested in production. I had to retreat from that solution for a few reasons (one of them was making the permissions available for other apps or frameworks), but I've spent several hours looking for a better approach with not much success.

Good luck,

R.

[alk]

This is great, and I love the views_cache idea.  Thanks a lot Robert -- much appreciated!