@st.cache_data cannot handle UUID objects (but @st.cache can)

[timothygebhard]

Checklist

• I have searched the existing issues for similar issues.
• I added a very descriptive title to this issue.
• I have provided sufficient information below to help reproduce this issue.

Summary

It looks like the "new" @st.cache_data decorator chokes on uuid.UUID objects, while the deprecated @st.cache seems to handle them just fine; see minimal example.

Reproducible Code Example

import streamlit as st
import uuid


@st.cache
def works(some_id: uuid.UUID) -> None:
    print("Works")


@st.cache_data
def doesnt_work(some_id: uuid.UUID) -> None:
    print("Nope")


some_id = uuid.uuid4()

works(some_id)
doesnt_work(some_id)

Steps To Reproduce

No response

Expected Behavior

No response

Current Behavior

The minimal example above produces the following output:

2023-04-06 10:46:30.563 WARNING streamlit.runtime.caching.cache_data_api: No runtime found, using MemoryCacheStorageManager
2023-04-06 10:46:30.678 
  Warning: to view this Streamlit app on a browser, run it with the following
  command:

    streamlit run /Users/timothy/Library/Application Support/JetBrains/PyCharmCE2023.1/scratches/scratch_7.py [ARGUMENTS]
2023-04-06 10:46:30.680 `st.cache` is deprecated. Please use one of Streamlit's new caching commands,
`st.cache_data` or `st.cache_resource`.

More information [in our docs](https://docs.streamlit.io/library/advanced-features/caching).
2023-04-06 10:46:30.681 No runtime found, using MemoryCacheStorageManager
Traceback (most recent call last):
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 383, in _to_bytes
    reduce_data = obj.__reduce__()
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/copyreg.py", line 76, in _reduce_ex
    raise TypeError(f"cannot pickle {cls.__name__!r} object")
TypeError: cannot pickle 'function' object

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/cache_utils.py", line 375, in _make_value_key
    update_hash(
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 56, in update_hash
    ch.update(hasher, val)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 209, in update
    b = self.to_bytes(obj)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 191, in to_bytes
    b = b"%s:%s" % (tname, self._to_bytes(obj))
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 239, in _to_bytes
    self.update(h, item)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 209, in update
    b = self.to_bytes(obj)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 191, in to_bytes
    b = b"%s:%s" % (tname, self._to_bytes(obj))
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 388, in _to_bytes
    self.update(h, item)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 209, in update
    b = self.to_bytes(obj)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 191, in to_bytes
    b = b"%s:%s" % (tname, self._to_bytes(obj))
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 385, in _to_bytes
    raise UnhashableTypeError() from ex
streamlit.runtime.caching.cache_errors.UnhashableTypeError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/timothy/Library/Application Support/JetBrains/PyCharmCE2023.1/scratches/scratch_7.py", line 20, in <module>
    doesnt_work(some_id)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/cache_utils.py", line 194, in wrapper
    return cached_func(*args, **kwargs)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/cache_utils.py", line 223, in __call__
    return self._get_or_create_cached_value(args, kwargs)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/cache_utils.py", line 237, in _get_or_create_cached_value
    value_key = _make_value_key(
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/cache_utils.py", line 381, in _make_value_key
    raise UnhashableParamError(cache_type, func, arg_name, arg_value, exc)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/cache_utils.py", line 375, in _make_value_key
    update_hash(
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 56, in update_hash
    ch.update(hasher, val)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 209, in update
    b = self.to_bytes(obj)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 191, in to_bytes
    b = b"%s:%s" % (tname, self._to_bytes(obj))
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 239, in _to_bytes
    self.update(h, item)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 209, in update
    b = self.to_bytes(obj)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 191, in to_bytes
    b = b"%s:%s" % (tname, self._to_bytes(obj))
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 388, in _to_bytes
    self.update(h, item)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 209, in update
    b = self.to_bytes(obj)
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 191, in to_bytes
    b = b"%s:%s" % (tname, self._to_bytes(obj))
  File "/usr/local/anaconda3/envs/demo-project/lib/python3.10/site-packages/streamlit/runtime/caching/hashing.py", line 385, in _to_bytes
    raise UnhashableTypeError() from ex
streamlit.runtime.caching.cache_errors.UnhashableParamError: Cannot hash argument 'some_id' (of type `uuid.UUID`) in 'doesnt_work'.

To address this, you can tell Streamlit not to hash this argument by adding a
leading underscore to the argument's name in the function signature:

\```
@st.cache_data
def doesnt_work(_some_id, ...):
    ...
\```
            
Works

Is this a regression?

• Yes, this used to work in a previous version.

Debug info

• Streamlit version: 1.20.0
• Python version: 3.10.10
• Operating System: macOS 13.2.1 (22D68)
• Browser: —
• Virtual environment: conda

Additional Information

The root of the problems seems to be this:

Cannot hash argument 'some_id' (of type `uuid.UUID`) in 'doesnt_work'.

Which is a little strange because pickling and hashing UUID objects does not seem to be a problem in general:

>>> import pickle
>>> import uuid
>>> pickle.dumps(uuid.uuid4())
b'\x80\x04\x950\x00\x00\x00\x00\x00\x00\x00\x8c\x04uuid\x94\x8c\x04UUID\x94\x93\x94)\x81\x94}\x94\x8c\x03int\x94\x8a\x10\xa8\x0eL\x84\x14\xd9\xcf\x8d\xae@M\x9e\x11\xb0\x9cvsb.'
>>> hash(uuid.uuid4())
1532964488252874118

A simple workaround for now is to cast UUID objects to strings (which are cacheable also with @st.cache_data), but of course it would be nicer if that were not necessary :)

Are you willing to submit a PR?

• Yes, I am willing to submit a PR!