Is it okay to set instance variables in a Django class based view?

django, django-class-based-views, python

Solution

According to the source of `django.views.generic.base.View.as_view`:

- on django startup, as_view() returns a function `view`, which is not called

- on request, `view()` is called, it instantiates the class and calls `dispatch()`

- the class instance is thread safe

According to the source of `django.views.generic.base.View.__init__`, the request object is out of scope at this point so you can't parse it in your own constructor overload.

However, you could parse the request and set class view instance attributes in an overload of `django.views.generic.base.View.dispatch`, this is safe according to the source:

class YourView(SomeView):
    def dispatch(self, request, *args, **kwargs):
        # parse the request here ie.
        self.foo = request.GET.get('foo', False)

        # call the view
        return super(YourView, self).dispatch(request, *args, **kwargs)

Problem

I trying out Django's class based views (CBVs). ``` class BlahView(TemplateView): template_name = 'blah/blah.html' def get_context_data(self, **kwargs): #code... def get(self, request, **kwargs): #more code... ``` Now, I know that I can get the request params from self.request. Now say I want to parse these request params and store them within the class. Can I store those in `self.xxx`? Now, obviously based on how classes work, this seems straightforward. But I can't make out the flow of control, looking at the definition of `View` (superclass of `TemplateView`). The source mentions `as_view()` to be the 'entry-point' I thought of setting my instance variables at the beginning of `get_context_data()` but that doesn't seem right to do initialization there. Can I define an `__init__()` for my CBV? If so, will there be threading issues or something where multiple page-accesses possibly work with a global instance of my parsed data? I know this sounds a bit messy, but I'm just a bit confused with the code flow in CBVs.

Original source