#3424 [BUG] FlyteFile cannot be used with `Annotated[FlyteFile, HashMethod(...)]` Issue created by AdrianoKF Describe the bug Original discussion on Slack: https://flyte-org.slack.com/archives/CP2HDHKE1/p1678183814829309 Using

Annotated[FlyteFile, HashMethod(...)]

for calculating a custom hash for a

FlyteFile

doesn't work out-of-the-box, failing an `issubclass` check in flytekit/types/file/file.py. This makes it impossible to use custom hash functions with

FlyteFile

, e.g., to implement content-aware caching. Note, that the same approach with

Annotated[FlyteDirectory, HashMethod(...)]

works as expected out of the box. Example workflow code

import hashlib
from typing import Annotated

import pandas as pd
from flytekit import task, workflow
from flytekit.core.hash import HashMethod
from flytekit.types.file import FlyteFile


def calc_hash(f: FlyteFile) -> str:
    """Calculate SHA1 hash of a file"""

    h = hashlib.sha1(usedforsecurity=False)
    with open(f.path, "rb") as f:
        while chunk := f.read(4096):
            h.update(chunk)
    return str(h.hexdigest())


CachedFlyteFile = Annotated[FlyteFile, HashMethod(calc_hash)]


@task
def write_file() -> CachedFlyteFile:
    print("write_file")
    local_path = "data.parquet"

    df = pd.DataFrame(data={"a": [1, 2, 3], "b": [3, 4, 5]})
    df.to_parquet(local_path)

    return FlyteFile(local_path, remote_path=f"<s3://test-repo/main/{local_path}>")


@task(cache=True, cache_version="1")
def print_file(file: FlyteFile) -> None:
    file.download()
    print(pd.read_parquet(file))


@workflow
def wf() -> None:
    f = write_file()
    print_file(file=f)


if __name__ == "__main__":
    wf()
    wf()  # don't expect output from `print_file`, since it should be cached

Expected behavior The first execution of

wf

should run both the

write_file

and

print_file

tasks, the second execution should only run

write_file

and hit the cache for

print_file

. In reality, an exception is raised in `flytekit/types/file/file.py, in to_literal()`:

TypeError: issubclass() arg 1 must be a class

Additional context to reproduce See example workflow above. I was able to solve the issue by inserting the following before the

issubclass

check in

flytekit/types/file/file.py

(I haven't run the flytekit test suite, so this might not be suitable for a mergeable PR just yet - should I submit a draft PR regardless?):

@@ -284,6 +288,10 @@
                 "None value cannot be converted to a file."
             )
 
+        # Handle Annotated[FlyteFile, ...] correctly by extracting the wrapped type
+        if issubclass(typing.get_origin(python_type), typing.Annotated):
+            python_type = typing.get_args(python_type)[0]
+
         if not (python_type is os.PathLike or issubclass(python_type, FlyteFile)):
             raise ValueError(
                 f"Incorrect type {python_type}, must be either a FlyteFile or os.PathLike"

Screenshots No response Are you sure this issue hasn't been raised already? ☑︎ Yes Have you read the Code of Conduct? ☑︎ Yes flyteorg/flyte