Caching
Backend
Functools cache
We currently use lru_cache for the retrieval of a particular ZGW service and the creation of a client from it.
The lru_cache does not expire, but it grows up to a maxsize (for more info, see the docs).
If there are any changes to the a Service, then a signal receiver will clear the cache.
There is also a signal receiver listening for changes to APIConfig which clears the cache for creating the client for the selectielijst API Service.
Django cache
We use the decorators @_cached and @_cached_with_args for functions that make requests to Open Zaak and perform expensive work with the results.
These decorators cache the results in the Django "default" cache. This gives us the possibility of easily clearing them all if we know that something has changed in Open Zaak.
@_cached_with_args is meant for functions that take one or more string arguments, for example urls:
@_cached_with_args
def retrieve_selectielijstklasse_resultaat(resultaat_url: str) -> JSONValue:
...
The View ClearDefaultCacheView enables to clear the default cache with an API call.
Tests
Previously we used to mock the get_solo method of Solo objects since this method caches the retrieved object.
Now, for the APIConfig model we have the APIConfigFactory, which clears the solo cache before creating a new solo object for the test.