Commit 99edbe0e authored by Tomek Paczkowski's avatar Tomek Paczkowski Committed by Honza Kral
Browse files

Fixed #19253 -- Extracted template cache key building logic 

Introduced a public function
django.core.cache.utils.make_template_fragment_key
Thanks @chrismedrela for fruitful cooperation.
parent b9cc6102

AUTHORS

+2 −0
Original line number Diff line number Diff line
@@ -382,6 +382,7 @@ answer newbie questions, and generally made Django that much better: 
    Paul McLanahan <paul@mclanahan.net>

    Tobias McNulty <http://www.caktusgroup.com/blog>

    Andrews Medina <andrewsmedina@gmail.com>

    Christoph Mędrela <chris.medrela@gmail.com>

    Zain Memon

    Christian Metts

    michal@plovarna.cz
@@ -418,6 +419,7 @@ answer newbie questions, and generally made Django that much better: 
    Christian Oudard <christian.oudard@gmail.com>

    oggie rob <oz.robharvey@gmail.com>

    oggy <ognjen.maric@gmail.com>

    Tomek Paczkowski <tomek@hauru.eu>

    Jens Page

    Jay Parlar <parlar@gmail.com>

    Carlos Eduardo de Paula <carlosedp@gmail.com>

django/core/cache/utils.py

0 → 100644
+15 −0
Original line number Diff line number Diff line 
from __future__ import absolute_import, unicode_literals



import hashlib

from django.utils.encoding import force_bytes

from django.utils.http import urlquote



TEMPLATE_FRAGMENT_KEY_TEMPLATE = 'template.cache.%s.%s'





def make_template_fragment_key(fragment_name, vary_on=None):

    if vary_on is None:

        vary_on = ()

    key = ':'.join([urlquote(var) for var in vary_on])

    args = hashlib.md5(force_bytes(key))

    return TEMPLATE_FRAGMENT_KEY_TEMPLATE % (fragment_name, args.hexdigest())

django/templatetags/cache.py

+3 −7
Original line number Diff line number Diff line 
from __future__ import unicode_literals



import hashlib

from django.core.cache.utils import make_template_fragment_key

from django.template import Library, Node, TemplateSyntaxError, VariableDoesNotExist

from django.core.cache import cache

from django.utils.encoding import force_bytes

from django.utils.http import urlquote



register = Library()
@@ -24,10 +22,8 @@ class CacheNode(Node): 
            expire_time = int(expire_time)

        except (ValueError, TypeError):

            raise TemplateSyntaxError('"cache" tag got a non-integer timeout value: %r' % expire_time)

        # Build a key for this fragment and all vary-on's.

        key = ':'.join([urlquote(var.resolve(context)) for var in self.vary_on])

        args = hashlib.md5(force_bytes(key))

        cache_key = 'template.cache.%s.%s' % (self.fragment_name, args.hexdigest())

        vary_on = [var.resolve(context) for var in self.vary_on]

        cache_key = make_template_fragment_key(self.fragment_name, vary_on)

        value = cache.get(cache_key)

        if value is None:

            value = self.nodelist.render(context)

docs/topics/cache.txt

+17 −0
Original line number Diff line number Diff line
@@ -639,6 +639,23 @@ equivalent: 
This feature is useful in avoiding repetition in templates. You can set the

timeout in a variable, in one place, and just reuse that value.



.. function:: django.core.cache.utils.make_template_fragment_key(fragment_name, vary_on=None)



If you want to obtain the cache key used for a cached fragment, you can use

``make_template_fragment_key``. ``fragment_name`` is the same as second argument

to the ``cache`` template tag; ``vary_on`` is a list of all additional arguments

passed to the tag. This function can be useful for invalidating or overwriting

a cached item, for example:



.. code-block:: python



    >>> from django.core.cache import cache

    >>> from django.core.cache.utils import make_template_fragment_key

    # cache key for {% cache 500 sidebar username %}

    >>> key = make_template_fragment_key('sidebar', [username])

    >>> cache.delete(key) # invalidates cached template fragment





The low-level cache API

=======================

tests/regressiontests/cache/tests.py

+23 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ from django.core.cache import get_cache 
from django.core.cache.backends.base import (CacheKeyWarning,

    InvalidCacheBackendError)

from django.db import router, transaction

from django.core.cache.utils import make_template_fragment_key

from django.http import (HttpResponse, HttpRequest, StreamingHttpResponse,

    QueryDict)

from django.middleware.cache import (FetchFromCacheMiddleware,
@@ -1809,3 +1810,25 @@ class TestEtagWithAdmin(TestCase): 
            response = self.client.get('/test_admin/admin/')

            self.assertEqual(response.status_code, 200)

            self.assertTrue(response.has_header('ETag'))





class TestMakeTemplateFragmentKey(TestCase):

    def test_without_vary_on(self):

        key = make_template_fragment_key('a.fragment')

        self.assertEqual(key, 'template.cache.a.fragment.d41d8cd98f00b204e9800998ecf8427e')



    def test_with_one_vary_on(self):

        key = make_template_fragment_key('foo', ['abc'])

        self.assertEqual(key,

            'template.cache.foo.900150983cd24fb0d6963f7d28e17f72')



    def test_with_many_vary_on(self):

        key = make_template_fragment_key('bar', ['abc', 'def'])

        self.assertEqual(key,

            'template.cache.bar.4b35f12ab03cec09beec4c21b2d2fa88')



    def test_proper_escaping(self):

        key = make_template_fragment_key('spam', ['abc:def%'])

        self.assertEqual(key,

            'template.cache.spam.f27688177baec990cdf3fbd9d9c3f469')