How to exclude parameters when caching function calls with DiskCache and memoize?

Question

I am using Python's DiskCache and the memoize decorator to cache function calls to a database of static data.

from diskcache import Cache
cache = Cache("database_cache)

@cache.memoize()
def fetch_document(row_id: int, user: str, password: str):
    ...

I don't want the user and password be part of the cache key.

How can I exclude parameters from the key generation?

Answer 1

Documentation for memoize doesn't show option to exclude parameters.

You may try to write own decorator - using source code.

Or use cache on your own inside fetch_document - something like this

def fetch_document(row_id: int, user: str, password: str):
    if row_id in cache:
         return cache[row_id]

    # ... code ...
              
    # result = ...

    cache[row_id] = result

    return result              

---

EDIT:

OR create cached version of your function - like this

def cached_fetch_document(row_id: int, user: str, password: str):
    if row_id in cache:
         return cache[row_id]

    result = fetch_document(row_id: int, user: str, password: str)

    cache[row_id] = result

    return result              

and later you can decide if you want to use cached_fetch_document in place of fetch_document

Answer 2

After version 5.3.0, memoize can use the ignore argument to ignore the positional arguments