Accessing the current view class instance in Django middleware

Question

Question:

I'm trying to access an attribute of the 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 a way to get this accomplished?

Thanks!

---

My first attempt:

I initially figured that the process_view() method might be a good place to do this. Unfortunately, the view_func argument it receives contains a function -- the output of MyView.as_view() -- rather than the view instance itself. From the Django docs:

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

...view_func is the Python function that Django is about to use. (It’s the actual function object, not the name of the function as a string.)...

---

My second attempt:

A handle to the view instance is available in process_template_response() method, but it's pretty awkward, and, in any case, I'd like to be able to work with my_attribute at an earlier point in the middleware stack. But this does work:

def process_template_response(self, request, response):
    my_attribute = response.context_data['view'].my_attribute

Answer 1

There is no built-in way to do this, but here is a solution given to me by a kindly user on the django-users mailing list. I'm reposting his suggestion here in case anyone else is trying to do the same thing.

This is useful if:

1. you want to identify properties of the current view in your middleware and perform processing accordingly, and;
2. for various reasons you don't want to use mixins or decorators to accomplish similar results.

This inspects the view_func object passed to the process_view() middleware hook and determines and imports the the appropriate view class.

# middleware.py
from myutils import get_class

def process_view(self, request, view_func, view_args, view_kwargs):
        view = get_class(view_func.__module__, view_func.__name__)
        view.my_attribute

Then your get_class() definition:

# myutils.py
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