Added a request argument to render_to_string.

This is for consistency with Template.render.

It adds a little bit of knowledge about HTTP requests in
django.template.loader but I think consistency trumps purity.

django/template/loader.py

@@ -80,7 +80,7 @@ def render_to_string(template_name, context=None,
                      context_instance=_context_instance_undefined,
                      dirs=_dirs_undefined,
                      dictionary=_dictionary_undefined,
-                     using=None):
+                     request=None, using=None):
     """
     Loads a template and renders it with a context. Returns a string.
 
@@ -94,7 +94,7 @@ def render_to_string(template_name, context=None,
             template = select_template(template_name, using=using)
         else:
             template = get_template(template_name, using=using)
-        return template.render(context)
+        return template.render(context, request)
 
     else:
         # Some deprecated arguments were passed - use the legacy code path
@@ -104,6 +104,11 @@ def render_to_string(template_name, context=None,
                 # to Django templates. Remove Engine.render_to_string() at the
                 # same time as this code path in Django 2.0.
                 if isinstance(engine, DjangoTemplates):
+                    if request is not None:
+                        raise ValueError(
+                            "render_to_string doesn't support the request argument "
+                            "when some deprecated arguments are passed.")
+                        continue
                     # Hack -- use the internal Engine instance of DjangoTemplates.
                     return engine.engine.render_to_string(
                         template_name, context, context_instance, dirs, dictionary)

docs/releases/1.8.txt

@@ -1351,8 +1351,10 @@ The following functions will no longer accept the ``dictionary`` and
 Use the ``context`` parameter instead. When ``dictionary`` is passed as a
 positional argument, which is the most common idiom, no changes are needed.
 
-There is no replacement for ``context_instance``. All data must be passed to
-templates through the ``context`` dict.
+If you're passing a :class:`~django.template.Context` in ``context_instance``,
+pass a :class:`dict` in the ``context`` parameter instead. If you're passing a
+:class:`~django.template.RequestContext`, pass the request separately in the
+``request`` parameter.
 
 ``dirs`` argument of template-finding functions
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

tests/template_loader/templates/template_loader/request.html

@@ -0,0 +1 @@
+{{ request.path }}

tests/template_loader/tests.py

@@ -1,4 +1,5 @@
 from django.test import override_settings, SimpleTestCase
+from django.test.client import RequestFactory
 from django.template import TemplateDoesNotExist
 from django.template.loader import (
     get_template, select_template, render_to_string)
@@ -10,6 +11,11 @@ from django.template.loader import (
 }, {
     'BACKEND': 'django.template.backends.django.DjangoTemplates',
     'APP_DIRS': True,
+    'OPTIONS': {
+        'context_processors': [
+            'django.template.context_processors.request',
+        ],
+    },
 }])
 class TemplateLoaderTests(SimpleTestCase):
 
@@ -66,6 +72,11 @@ class TemplateLoaderTests(SimpleTestCase):
         content = render_to_string("template_loader/goodbye.html")
         self.assertEqual(content, "Goodbye! (Django templates)\n")
 
+    def test_render_to_string_with_request(self):
+        request = RequestFactory().get('/foobar/')
+        content = render_to_string("template_loader/request.html", request=request)
+        self.assertEqual(content, "/foobar/\n")
+
     def test_render_to_string_using_engine(self):
         content = render_to_string("template_loader/hello.html", using="django")
         self.assertEqual(content, "Hello! (Django templates)\n")