Fixed #19878 -- Deprecated TemplateView passing URL kwargs into context.

django/views/generic/base.py

@@ -1,4 +1,5 @@
 import logging
+import warnings
 from functools import update_wrapper
 
 from django.core.exceptions import ImproperlyConfigured
@@ -9,6 +10,8 @@ from django.http import (
 from django.template.response import TemplateResponse
 from django.urls import reverse
 from django.utils.decorators import classonlymethod
+from django.utils.deprecation import RemovedInDjango40Warning
+from django.utils.functional import SimpleLazyObject
 
 logger = logging.getLogger('django.request')
 
@@ -152,14 +155,33 @@ class TemplateResponseMixin:
 
 
 class TemplateView(TemplateResponseMixin, ContextMixin, View):
-    """
+    """Render a template."""
-    Render a template. Pass keyword arguments from the URLconf to the context.
-    """
     def get(self, request, *args, **kwargs):
-        context = self.get_context_data(**kwargs)
+        # RemovedInDjango40Warning: when the deprecation ends, replace with:
+        #   context = self.get_context_data()
+        context_kwargs = _wrap_url_kwargs_with_deprecation_warning(kwargs)
+        context = self.get_context_data(**context_kwargs)
         return self.render_to_response(context)
 
 
+# RemovedInDjango40Warning
+def _wrap_url_kwargs_with_deprecation_warning(url_kwargs):
+    context_kwargs = {}
+    for key, value in url_kwargs.items():
+        # Bind into function closure.
+        @SimpleLazyObject
+        def access_value(key=key, value=value):
+            warnings.warn(
+                'TemplateView passing URL kwargs to the context is '
+                'deprecated. Reference %s in your template through '
+                'view.kwargs instead.' % key,
+                RemovedInDjango40Warning, stacklevel=2,
+            )
+            return value
+        context_kwargs[key] = access_value
+    return context_kwargs
+
+
 class RedirectView(View):
     """Provide a redirect on any GET request."""
     permanent = False

docs/internals/deprecation.txt

@@ -66,6 +66,9 @@ details on these changes.
 
 * The ``list`` message for ``ModelMultipleChoiceField`` will be removed.
 
+* ``django.views.generic.TemplateView`` will no longer pass URL kwargs directly
+  to the ``context``.
+
 See the :ref:`Django 3.1 release notes <deprecated-features-3.1>` for more
 details on these changes.
 

docs/ref/class-based-views/base.txt

@@ -117,8 +117,7 @@ MRO is an acronym for Method Resolution Order.
 
 .. class:: django.views.generic.base.TemplateView
 
-    Renders a given template, with the context containing parameters captured
+    Renders a given template.
-    in the URL.
 
     **Ancestors (MRO)**
 
@@ -162,12 +161,17 @@ MRO is an acronym for Method Resolution Order.
 
     **Context**
 
-    * Populated (through :class:`~django.views.generic.base.ContextMixin`) with
+    * Populated (through :class:`~django.views.generic.base.ContextMixin`).
-      the keyword arguments captured from the URL pattern that served the view.
     * You can also add context using the
       :attr:`~django.views.generic.base.ContextMixin.extra_context` keyword
       argument for :meth:`~django.views.generic.base.View.as_view`.
 
+    .. deprecated:: 3.1
+
+        Starting in Django 4.0, the keyword arguments captured from the URL
+        pattern won't be passed to the context. Reference them with
+        ``view.kwargs`` instead.
+
 ``RedirectView``
 ================
 

docs/releases/3.1.txt

@@ -640,6 +640,10 @@ Miscellaneous
 * The ``list`` message for :class:`~django.forms.ModelMultipleChoiceField` is
   deprecated in favor of ``invalid_list``.
 
+* The passing of URL kwargs directly to the context by
+  :class:`~django.views.generic.base.TemplateView` is deprecated. Reference
+  them in the template with ``view.kwargs`` instead.
+
 .. _removed-features-3.1:
 
 Features removed in 3.1

tests/generic_views/test_base.py

@@ -2,9 +2,12 @@ import time
 
 from django.core.exceptions import ImproperlyConfigured
 from django.http import HttpResponse
-from django.test import RequestFactory, SimpleTestCase, override_settings
+from django.test import (
+    RequestFactory, SimpleTestCase, ignore_warnings, override_settings,
+)
 from django.test.utils import require_jinja2
 from django.urls import resolve
+from django.utils.deprecation import RemovedInDjango40Warning
 from django.views.generic import RedirectView, TemplateView, View
 
 from . import views
@@ -347,25 +350,6 @@ class TemplateViewTest(SimpleTestCase):
         view = TemplateView.as_view(template_name='generic_views/using.html', template_engine='jinja2')
         self.assertEqual(view(request).render().content, b'Jinja2\n')
 
-    def test_template_params(self):
-        """
-        A generic template view passes kwargs as context.
-        """
-        response = self.client.get('/template/simple/bar/')
-        self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.context['foo'], 'bar')
-        self.assertIsInstance(response.context['view'], View)
-
-    def test_extra_template_params(self):
-        """
-        A template view can be customized to return extra context.
-        """
-        response = self.client.get('/template/custom/bar/')
-        self.assertEqual(response.status_code, 200)
-        self.assertEqual(response.context['foo'], 'bar')
-        self.assertEqual(response.context['key'], 'value')
-        self.assertIsInstance(response.context['view'], View)
-
     def test_cached_views(self):
         """
         A template view can be cached
@@ -584,3 +568,38 @@ class SingleObjectTemplateResponseMixinTest(SimpleTestCase):
         )
         with self.assertRaisesMessage(ImproperlyConfigured, msg):
             view.get_template_names()
+
+
+@override_settings(ROOT_URLCONF='generic_views.urls')
+class DeprecationTests(SimpleTestCase):
+    @ignore_warnings(category=RemovedInDjango40Warning)
+    def test_template_params(self):
+        """A generic template view passes kwargs as context."""
+        response = self.client.get('/template/simple/bar/')
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.context['foo'], 'bar')
+        self.assertIsInstance(response.context['view'], View)
+
+    @ignore_warnings(category=RemovedInDjango40Warning)
+    def test_extra_template_params(self):
+        """A template view can be customized to return extra context."""
+        response = self.client.get('/template/custom/bar1/bar2/')
+        self.assertEqual(response.status_code, 200)
+        self.assertEqual(response.context['foo1'], 'bar1')
+        self.assertEqual(response.context['foo2'], 'bar2')
+        self.assertEqual(response.context['key'], 'value')
+        self.assertIsInstance(response.context['view'], View)
+
+    def test_template_params_warning(self):
+        response = self.client.get('/template/custom/bar1/bar2/')
+        self.assertEqual(response.status_code, 200)
+        msg = (
+            'TemplateView passing URL kwargs to the context is deprecated. '
+            'Reference %s in your template through view.kwargs instead.'
+        )
+        with self.assertRaisesMessage(RemovedInDjango40Warning, msg % 'foo1'):
+            str(response.context['foo1'])
+        with self.assertRaisesMessage(RemovedInDjango40Warning, msg % 'foo2'):
+            str(response.context['foo2'])
+        self.assertEqual(response.context['key'], 'value')
+        self.assertIsInstance(response.context['view'], View)

tests/generic_views/urls.py

@@ -12,7 +12,10 @@ urlpatterns = [
     path('template/no_template/', TemplateView.as_view()),
     path('template/login_required/', login_required(TemplateView.as_view())),
     path('template/simple/<foo>/', TemplateView.as_view(template_name='generic_views/about.html')),
-    path('template/custom/<foo>/', views.CustomTemplateView.as_view(template_name='generic_views/about.html')),
+    path(
+        'template/custom/<foo1>/<foo2>/',
+        views.CustomTemplateView.as_view(template_name='generic_views/about.html'),
+    ),
     path(
         'template/content_type/',
         TemplateView.as_view(template_name='generic_views/robots.txt', content_type='text/plain'),