Fixed #24694 -- Added support for context_processors to Jinja2 backend.

4 files changed, 50 insertions, 7 deletions

diff --git a/django/template/backends/jinja2.py b/django/template/backends/jinja2.py
index 7cdf4cd190..54f6f6c9d2 100644
--- a/django/template/backends/jinja2.py
+++ b/django/template/backends/jinja2.py
@@ -8,6 +8,7 @@ import jinja2
 from django.conf import settings
 from django.template import TemplateDoesNotExist, TemplateSyntaxError
 from django.utils import six
+from django.utils.functional import cached_property
 from django.utils.module_loading import import_string
 
 from .base import BaseEngine
@@ -23,6 +24,8 @@ class Jinja2(BaseEngine):
         options = params.pop('OPTIONS').copy()
         super(Jinja2, self).__init__(params)
 
+        self.context_processors = options.pop('context_processors', [])
+
         environment = options.pop('environment', 'jinja2.Environment')
         environment_cls = import_string(environment)
 
@@ -36,11 +39,11 @@ class Jinja2(BaseEngine):
         self.env = environment_cls(**options)
 
     def from_string(self, template_code):
-        return Template(self.env.from_string(template_code))
+        return Template(self.env.from_string(template_code), self)
 
     def get_template(self, template_name):
         try:
-            return Template(self.env.get_template(template_name))
+            return Template(self.env.get_template(template_name), self)
         except jinja2.TemplateNotFound as exc:
             six.reraise(
                 TemplateDoesNotExist,
@@ -52,11 +55,16 @@ class Jinja2(BaseEngine):
             new.template_debug = get_exception_info(exc)
             six.reraise(TemplateSyntaxError, new, sys.exc_info()[2])
 
+    @cached_property
+    def template_context_processors(self):
+        return [import_string(path) for path in self.context_processors]
+
 
 class Template(object):
 
-    def __init__(self, template):
+    def __init__(self, template, backend):
         self.template = template
+        self.backend = backend
         self.origin = Origin(
             name=template.filename, template_name=template.name,
         )
@@ -68,6 +76,8 @@ class Template(object):
             context['request'] = request
             context['csrf_input'] = csrf_input_lazy(request)
             context['csrf_token'] = csrf_token_lazy(request)
+            for context_processor in self.backend.template_context_processors:
+                context.update(context_processor(request))
         return self.template.render(context)
 
 
diff --git a/docs/releases/1.11.txt b/docs/releases/1.11.txt
index 974e1e4adb..5bac7e0b0a 100644
--- a/docs/releases/1.11.txt
+++ b/docs/releases/1.11.txt
@@ -220,6 +220,10 @@ Templates
 
 * :meth:`~django.utils.safestring.mark_safe` can now be used as a decorator.
 
+* The :class:`~django.template.backends.jinja2.Jinja2` template backend now
+  supports context processors by setting the ``'context_processors'`` option in
+  :setting:`OPTIONS <TEMPLATES-OPTIONS>`.
+
 Tests
 ~~~~~
 
diff --git a/docs/topics/templates.txt b/docs/topics/templates.txt
index 8f21f936ab..2fa9bcfeac 100644
--- a/docs/topics/templates.txt
+++ b/docs/topics/templates.txt
@@ -398,13 +398,27 @@ adds defaults that differ from Jinja2's for a few options:
 * ``'auto_reload'``: ``settings.DEBUG``
 * ``'undefined'``: ``DebugUndefined if settings.DEBUG else Undefined``
 
+``Jinja2`` engines also accept the following :setting:`OPTIONS
+<TEMPLATES-OPTIONS>`:
+
+* ``'context_processors'``: a list of dotted Python paths to callables that
+  are used to populate the context when a template is rendered with a request.
+  These callables take a request object as their argument and return a
+  :class:`dict` of items to be merged into the context.
+
+  It defaults to an empty list.
+
+.. versionadded:: 1.11
+
+    The ``'context_processors'`` option was added.
+
 The default configuration is purposefully kept to a minimum. If a template is
 rendered with a request (e.g. when using :py:func:`~django.shortcuts.render`),
 the ``Jinja2`` backend adds the globals ``request``, ``csrf_input``, and
 ``csrf_token`` to the context. Apart from that, this backend doesn't create a
-Django-flavored environment. It doesn't know about Django context processors,
-filters, and tags. In order to use Django-specific APIs, you must configure
-them into the environment.
+Django-flavored environment. It doesn't know about Django filters and tags.
+In order to use Django-specific APIs, you must configure them into the
+environment.
 
 For example, you can create ``myproject/jinja2.py`` with this content::
 
diff --git a/tests/template_backends/test_jinja2.py b/tests/template_backends/test_jinja2.py
index 831a84c8c0..a79c6bc460 100644
--- a/tests/template_backends/test_jinja2.py
+++ b/tests/template_backends/test_jinja2.py
@@ -5,6 +5,7 @@ from __future__ import absolute_import
 from unittest import skipIf
 
 from django.template import TemplateSyntaxError
+from django.test import RequestFactory
 
 from .test_dummy import TemplateStringsTests
 
@@ -22,7 +23,12 @@ class Jinja2Tests(TemplateStringsTests):
 
     engine_class = Jinja2
     backend_name = 'jinja2'
-    options = {'keep_trailing_newline': True}
+    options = {
+        'keep_trailing_newline': True,
+        'context_processors': [
+            'django.template.context_processors.static',
+        ],
+    }
 
     def test_origin(self):
         template = self.engine.get_template('template_backends/hello.html')
@@ -74,3 +80,12 @@ class Jinja2Tests(TemplateStringsTests):
         self.assertEqual(len(debug['source_lines']), 21)
         self.assertTrue(debug['name'].endswith('syntax_error2.html'))
         self.assertIn('message', debug)
+
+    def test_context_processors(self):
+        request = RequestFactory().get('/')
+        template = self.engine.from_string('Static URL: {{ STATIC_URL }}')
+        content = template.render(request=request)
+        self.assertEqual(content, 'Static URL: /static/')
+        with self.settings(STATIC_URL='/s/'):
+            content = template.render(request=request)
+        self.assertEqual(content, 'Static URL: /s/')