User guide¶
Installation¶
Install with pip or easy_install:
pip install --upgrade requests-cache
or download latest version from version control:
git clone git://github.com/reclosedev/requests-cache.git
cd requests-cache
python setup.py install
Usage¶
There is two ways of using requests_cache
:
- Using
CachedSession
insteadrequests.Session
- Monkey patching
requests
to useCachedSession
by default
Monkey-patching allows to add caching to existent program by adding just two lines:
Import requests_cache
and call install_cache()
import requests
import requests_cache
requests_cache.install_cache()
And you can use requests
, all responses will be cached transparently!
For example, following code will take only 1-2 seconds instead 10:
for i in range(10):
requests.get('http://httpbin.org/delay/1')
Cache can be configured with some options, such as cache filename, backend
(sqlite, mongodb, redis, memory), expiration time, etc. E.g. cache stored in sqlite
database (default format) named 'test_cache.sqlite'
with expiration
set to 300 seconds can be configured as:
requests_cache.install_cache('test_cache', backend='sqlite', expire_after=300)
See also
Full list of options can be found in
requests_cache.install_cache()
reference
Transparent caching is achieved by monkey-patching requests
library
It is possible to uninstall this patch with requests_cache.uninstall_cache()
.
Also, you can use requests_cache.disabled()
context manager for temporary disabling caching:
with requests_cache.disabled():
print(requests.get('http://httpbin.org/ip').text)
If Response
is taken from cache, from_cache
attribute will be True
:
>>> import requests
>>> import requests_cache
>>> requests_cache.install_cache()
>>> requests_cache.clear()
>>> r = requests.get('http://httpbin.org/get')
>>> r.from_cache
False
>>> r = requests.get('http://httpbin.org/get')
>>> r.from_cache
True
It can be used, for example, for request throttling with help of requests
hook system:
import time
import requests
import requests_cache
def make_throttle_hook(timeout=1.0):
"""
Returns a response hook function which sleeps for `timeout` seconds if
response is not cached
"""
def hook(response):
if not getattr(response, 'from_cache', False):
print 'sleeping'
time.sleep(timeout)
return response
return hook
if __name__ == '__main__':
requests_cache.install_cache('wait_test')
requests_cache.clear()
s = requests_cache.CachedSession()
s.hooks = {'response': make_throttle_hook(0.1)}
s.get('http://httpbin.org/delay/get')
s.get('http://httpbin.org/delay/get')
See also
Persistence¶
requests_cache
designed to support different backends for persistent storage.
By default it uses sqlite
database. Type of storage can be selected with backend
argument of install_cache()
.
List of available backends:
'sqlite'
- sqlite database (default)'memory'
- not persistent, stores all data in Pythondict
in memory'mongodb'
- (experimental) MongoDB database (pymongo
required)'redis'
- stores all data on a redis data store (redis
required)Note
pymongo
doesn’t work fine with gevent which powers grequests, but there is some workarounds, see question on StackOverflow.
You can write your own and pass instance to install_cache()
or CachedSession
constructor.
See Cache backends API documentation and sources.
Backward incompatible changes¶
There is backward incompatible changes introduced in version 0.3.0:
- expire_after is now seconds
- UTC time in cache
- Deleted
requests_cache.enabled()
context manager - Storage backends are now using hash for keys
- Renamed methods in backends
For more information see API reference .