Challenge 2: Convert It to a Class-Based View — Possible Solution
====================================================================

# catalog/views.py

from django.http import HttpResponse
from django.views import View

class SubscribeView(View):
    def get(self, request):
        form_html = """
            <form method="post">
                <input type="email" name="email" placeholder="you@example.com">
                <button type="submit">Subscribe</button>
            </form>
        """
        return HttpResponse(form_html)

    def post(self, request):
        email = request.POST.get("email", "")
        if not email:
            return HttpResponse("Please provide an email address.", status=400)
        return HttpResponse(f"Thanks — {email} is now subscribed!")

# catalog/urls.py
from django.urls import path
from . import views

urlpatterns = [
    path("subscribe/", views.SubscribeView.as_view(), name="subscribe"),
]

WHY THIS WORKS
--------------
- The single subscribe(request) function split cleanly into two methods,
  get() and post(), because View's dispatch mechanism reads
  request.method internally and calls whichever method matches — there's
  no need to write the `if request.method == "POST"` check by hand
  anymore; the base class does that branching for you.
- Both methods take `self` in addition to `request` — a detail easy to
  forget coming from FBVs, since these are genuinely instance methods on
  the view class, not standalone functions.
- The urls.py change is the one piece that's easy to miss: `path()`
  expects a callable, and a class itself isn't directly callable in the
  way View expects — `.as_view()` returns the actual callable function
  that path() needs, which is why forgetting `.as_view()` (passing
  `views.SubscribeView` instead of `views.SubscribeView.as_view()`) is a
  very common first mistake when adopting CBVs.