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#!/usr/bin/env python
"""
Example of a custom {ref}`request matcher <matching>` that caches a new response if the version of
requests-cache, requests, or urllib3 changes.
This generally isn't needed, since anything that causes a deserialization error will simply result
in a new request being sent and cached. But you might want to include a library version in your cache
key if, for example, you suspect a change in the library does not cause errors but **results in
different response content**.
This uses info from {py:func}`requests.help.info`. You can also preview this info from the command
line to see what else is available:
```bash
python -m requests.help
```
"""
from hashlib import sha256
from unittest.mock import patch
from requests import PreparedRequest
from requests.help import info as get_requests_info
import requests_cache
from requests_cache import CachedSession
from requests_cache.cache_keys import create_key
def create_custom_key(request: PreparedRequest, **kwargs) -> str:
"""Make a custom cache key that includes library versions"""
# Start with the default key created by requests-cache
base_key = create_key(request, **kwargs)
key = sha256()
key.update(base_key.encode('utf-8'))
# Add versions of requests-cache, requests, and urllib3
requests_info = get_requests_info()
for lib in ['requests', 'urllib3']:
key.update(requests_info[lib]['version'].encode('utf-8'))
key.update(requests_cache.__version__.encode('utf-8'))
return key.hexdigest()
def test_cache_key():
"""Test that the custom cache keys are working as expected"""
session = CachedSession('key-test', key_fn=create_custom_key)
session.cache.clear()
session.get('https://httpbin.org/get')
response = session.get('https://httpbin.org/get')
assert response.from_cache is True
# Simulate a major version change
new_versions = {
'requests': {'version': '3.0.0'},
'urllib3': {'version': '2.0.0'},
}
with patch('__main__.get_requests_info', return_value=new_versions):
# A new request will be sent since the cache key no longer matches
response = session.get('https://httpbin.org/get')
assert response.from_cache is False
if __name__ == '__main__':
test_cache_key()
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