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Tag "cache"

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Scoped Cache Compatible with Django Caching Helpers

Have you ever felt the need to run multiple Django projects on the same memcached server? How about other cache backends? To scope the cache keys, you simply need to prefix. However, since a lot of Django's internals rely on `django.core.cache.cache`, you cannot easily replace it everywhere. This will automatically upgrade the `django.core.cache.cache` object if `settings.CACHE_PREFIX` is set to a string and the Middleware contains `ScopeCacheMiddleware`. A thread discussing the merging of this functionality into Django is available on [the dev mailing list](http://groups.google.com/group/django-developers/browse_thread/thread/d45edaafec56da2a). However, (as of now) nowhere in the thread does anyone mention the reason why this sort of treatment is needed: Many of Django's internal caching helpers use `django.core.cache.cache`, and will then conflict if multiple sites run on the same cache stores. Example Usage: >>> from django.conf import settings >>> from django.core.cache import cache >>> from scoped_caching import prefix_cache_object >>> settings.CACHE_PREFIX 'FOO_' # Do this once a process (e.g. on import or Middleware) >>> prefix_cache_object(settings.CACHE_PREFIX, cache) >>> cache.set("pi", 3.14159) >>> cache.get("pi") 3.14159 >>> cache.get("pi", use_global_namespace=True) >>> cache.get("FOO_pi", use_global_namespace=True) 3.14159 >>> cache.set("FOO_e", 2.71828, use_global_namespace=True) >>> cache.get("e") 2.71828 To Install: Simply add `ScopeCacheMiddleware` as a middleware and define `settings.CACHE_PREFIX` and enjoy!

  • middleware
  • cache
  • namespace
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Caching XHTML render_to_response

This code improves on Django's render_to_response shortcut function in the following ways: 1. If the caller does not provide a MIME type, and the caller is passing a RequestContext, it interrogates the request to determine if the HTTP client supports application/xhtml+xml encoding. If so, it sets the request type to application/xhtml+xml to override the HttpRequest class's default mime type of text/html. 2. It caches parsed templates in its own cache to improve performance. If you aren't using XHTML in your templates, you may choose to comment out the code that tests for and sets the application/xhtml+xml MIME type. I place this code in a file named "util.py" in my application. In my views, I write "from app.util import render_to_response" where I used to write "from django.shortcuts import render_to_response". Note that the caching functionality provided by this code means that you will need to recycle your Django instance when you make template changes. Instructions for doing this depend on how you have deployed your Django application.

  • render_to_response
  • template
  • cache
  • html
  • xhtml
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very simplistic url cache flushing

This is an (overly simple) example of how to manually delete something from the cache. Usage is simply `delete_url_cache('/some_view/')` This most likely doesn't work when using Vary headers but does seem to work fine for the most general case of simply needing to programmatically flush the cache after certain actions.

  • cache
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Author: jpt
  • 1
  • 3

Decorator cache handler per view

The @cache_holding decorator works in a per-function base, you can specify a list of models or just a model and the second argument is the time in seconds to be cached. You can modify the proxy class by a keyword argument so you can do cache to all kind of things, also if you want to use a prefix as key + the hash value you can specify the prefix keyword argument.

  • cache
  • view
  • decorator
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Prefill ForeignKey caches

Provides an efficient means of looking up multiple related model instances for a range of objects by pre-filling the cache attribute used by `SingleRelatedObjectDescriptor` with either complete model instances or a dict containing only specified fields, looking up all required data with a single query. Example usage: C:\django_projects\soclone>django-admin.py shell >>> from soclone.models import Question >>> from soclone.views import populate_fk_caches >>> from django.db import connection >>> from django.contrib.auth.models import User >>> q = Question.objects.get(id=1) >>> a = list(q.answers.all()) >>> connection.queries = [] >>> populate_fk_caches(User, ( ... ((q,), ('author', 'last_edited_by', 'closed_by')), ... (a, ('author', 'last_edited_by')), ... ), ... fields=('username', 'gravatar', 'reputation', 'gold', 'silver', ... 'bronze')) >>> connection.queries [{'time': '0.000', 'sql': u'SELECT "auth_user"."id", "auth_user"."username", "au th_user"."gravatar", "auth_user"."reputation", "auth_user"."gold", "auth_user"." silver", "auth_user"."bronze" FROM "auth_user" WHERE "auth_user"."id" IN (1, 2)' }]

  • foreignkey
  • cache
  • prefill
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Safer cache key generation

If any cache keys you generate include user (staff or public) supplied data, they may: be too long, contain invalid characters (at least by memcache's standards), or both. This helper will sub out any invalid characters and md5 the key if it's too long. Additionally, it'll insert the CACHE_MIDDLEWARE_KEY_PREFIX from django.conf.settings for you. In your memcache instances are used by multiple applications (Django or otherwise) this can help ensure your keys are unique to that a particular app on a particular site.

  • memcache
  • cache
  • caching
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Database Cache Management View

A simple view used to manage the page cache stored in the database (here Postgresql in the django_cache table, you also have to set correctly CACHE_TABLE_OID, by the OID of the cache table (you can get it in PgAdmin)

  • admin
  • cache
  • view
  • postgresql
  • management
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Language aware cache decorator

Caches a view based on the users language code, a cache_key and optional function arguments. The cache_key can be a string, a callable or None. If it's None, the the name of the decorated function is used. You can pass a tuple `func_args` of arguments. If passed, these arguments are part of the cache key. See examples for details.

  • cache
  • decorator
  • caching
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limit view request rate decorator

Limit rate request decorator for view. Authenificated user can't request decorated view often then timeout. Usage: @limit_request_rate(time_beetween_request_sec) def my_view(request): ... get_cell_value from [here](http://code.activestate.com/recipes/439096/)

  • django
  • cache
  • view
  • decorator
  • limit-request-rate
  • closure
  • cell
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cache_page that does nothing

When debugging/developing you want to be able to refresh your views every time you make a little change. But when in production mode you might want to cache these views because they contain long and resource hungry calculations or something. By putting this above "hack" in after importing `cache_page` you only cache the views in production mode.

  • cache
  • decorator
  • cache_page
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Conditional Caching

This trick is for caching a view only if it passes some condition, for example, if there are more than zero items in a list. The same methodology could be used for conditional applying of other decorators.

  • views
  • cache
  • decorators
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