maya-chen/flask
1
0
Fork 0
forked from orbit-oss/flask
Code Pull requests Activity

Update documentation for users to use flask-caching instead of the deprecated Werkzeug cache

Browse source
This commit is contained in:
Andrew Crouse 2018-11-12 13:20:07 -07:00 • committed by David Lord
parent f7e7f2ab11
commit aec0cdc016
No known key found for this signature in database
GPG key ID: 7A1C87E3F5BC42A8
1 changed files with 4 additions and 55 deletions
Download patch file Download diff file Expand all files Collapse all files

59
docs/patterns/caching.rst
View file

@ -10,60 +10,9 @@ still be good enough if they were 5 minutes old. So then the idea is that
you actually put the result of that calculation into a cache for some you actually put the result of that calculation into a cache for some
time. time.
Flask itself does not provide caching for you, but Werkzeug, one of the Flask itself does not provide caching for you, but `Flask-Caching`_, an
libraries it is based on, has some very basic cache support. It supports extentions for Flask does. Flask-Caching supports various backends, and it is
multiple cache backends, normally you want to use a memcached server. even possible to develop your own caching backend.
Setting up a Cache
------------------
You create a cache object once and keep it around, similar to how .. _Flask-Caching: https://flask-caching.readthedocs.io/en/latest/
:class:`~flask.Flask` objects are created. If you are using the
development server you can create a
:class:`~werkzeug.contrib.cache.SimpleCache` object, that one is a simple
cache that keeps the item stored in the memory of the Python interpreter::
from werkzeug.contrib.cache import SimpleCache
cache = SimpleCache()
If you want to use memcached, make sure to have one of the memcache modules
supported (you get them from `PyPI <https://pypi.org/>`_) and a
memcached server running somewhere. This is how you connect to such an
memcached server then::
from werkzeug.contrib.cache import MemcachedCache
cache = MemcachedCache(['127.0.0.1:11211'])
If you are using App Engine, you can connect to the App Engine memcache
server easily::
from werkzeug.contrib.cache import GAEMemcachedCache
cache = GAEMemcachedCache()
Using a Cache
-------------
Now how can one use such a cache? There are two very important
operations: :meth:`~werkzeug.contrib.cache.BaseCache.get` and
:meth:`~werkzeug.contrib.cache.BaseCache.set`. This is how to use them:
To get an item from the cache call
:meth:`~werkzeug.contrib.cache.BaseCache.get` with a string as key name.
If something is in the cache, it is returned. Otherwise that function
will return ``None``::
rv = cache.get('my-item')
To add items to the cache, use the :meth:`~werkzeug.contrib.cache.BaseCache.set`
method instead. The first argument is the key and the second the value
that should be set. Also a timeout can be provided after which the cache
will automatically remove item.
Here a full example how this looks like normally::
def get_my_item():
rv = cache.get('my-item')
if rv is None:
rv = calculate_value()
cache.set('my-item', rv, timeout=5 * 60)
return rv