Skip to main content
Python Software Foundation 20th Year Anniversary Fundraiser  Donate today!

Simple user directory respecting JSON cache for expensive functions.

Project description

Provides a function decorator that caches the return value in a JSON file in the appropriate application cache directory.

It requires all function parameters and return values to be encodeable to JSON, so that the cache is human-readable.

It supports a “vary” guard value (e.g. a data model version) that protects against using old versions of cache.

Additionally, a cheaper default function (e.g. returning shipped, precalculated values) can be specified as a stand-in until an explicit recalculate function is called.


Example usage:

from app_json_file_cache import AppCache
cache = AppCache("myapp")

def expensive_function():
    return calculator()

More Example usage:

from app_json_file_cache import AppCache
cache = AppCache("myapp")

@cache("expensive", vary=VERSION)
def expensive_function(param):
    return calculator(param)

expensive_function.recalculate(param1) # recalculate if external effects change

Using a default function until the next recalculate:

from app_json_file_cache import AppCache
cache = AppCache("myapp")

def cheap_standin(param):
    return estimate(param)

@cache("expensive", vary=VERSION, cheap_default_func=cheap_standin)
def expensive_function(param):
    return calculator(param)

expensive_function(param1) # cheap_standin is used
expensive_function.recalculate(param1) # cache is updated with expensive_function
expensive_function(param1) # cached value from expensive_function is used


  • Names must be unique per app. If you reuse names, chaos ensues.
  • Each set of function parameter values creates a new file. This may lead to too many files in a directory on some systems.
  • Mixing positional and keyword arguments is not supported
  • It’s your responsibility that return values are serializable to JSON.

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for app-json-file-cache, version 0.2.2
Filename, size File type Python version Upload date Hashes
Filename, size app_json_file_cache-0.2.2-py2.py3-none-any.whl (6.1 kB) File type Wheel Python version py2.py3 Upload date Hashes View
Filename, size app_json_file_cache-0.2.2.tar.gz (3.8 kB) File type Source Python version None Upload date Hashes View

Supported by

AWS AWS Cloud computing Datadog Datadog Monitoring DigiCert DigiCert EV certificate Facebook / Instagram Facebook / Instagram PSF Sponsor Fastly Fastly CDN Google Google Object Storage and Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Salesforce Salesforce PSF Sponsor Sentry Sentry Error logging StatusPage StatusPage Status page