aiofiles is an Apache2 licensed library, written in Python, for handling local disk files in asyncio applications.
Ordinary local file IO is blocking, and cannot easily and portably be made asynchronous. This means doing file IO may interfere with asyncio applications, which shouldn't block the executing thread. aiofiles helps with this by introducing asynchronous versions of files that support delegating operations to a separate thread pool.
async with aiofiles.open('filename', mode='r') as f:
contents = await f.read()
print(contents)
'My file contents'
Asynchronous iteration is also supported.
async with aiofiles.open('filename') as f:
async for line in f:
...
Asynchronous interface to tempfile module.
async with aiofiles.tempfile.TemporaryFile('wb') as f:
await f.write(b'Hello, World!')
async/await (PEP 492) constructsTo install aiofiles, simply:
$ pip install aiofiles
Files are opened using the aiofiles.open() coroutine, which in addition to
mirroring the builtin open accepts optional loop and executor
arguments. If loop is absent, the default loop will be used, as per the
set asyncio policy. If executor is not specified, the default event loop
executor will be used.
In case of success, an asynchronous file object is returned with an API identical to an ordinary file, except the following methods are coroutines and delegate to an executor:
closeflushisattyreadreadallread1readintoreadlinereadlinesseekseekabletelltruncatewritablewritewritelinesIn case of failure, one of the usual exceptions will be raised.
aiofiles.stdin, aiofiles.stdout, aiofiles.stderr,
aiofiles.stdin_bytes, aiofiles.stdout_bytes, and
aiofiles.stderr_bytes provide async access to sys.stdin,
sys.stdout, sys.stderr, and their corresponding .buffer properties.
The aiofiles.os module contains executor-enabled coroutine versions of
several useful os functions that deal with files:
statstatvfssendfilerenamerenamesreplaceremoveunlinkmkdirmakedirsrmdirremovedirslinksymlinkreadlinklistdirscandiraccessgetcwdpath.abspathpath.existspath.isfilepath.isdirpath.islinkpath.ismountpath.getsizepath.getatimepath.getctimepath.samefilepath.sameopenfileaiofiles.tempfile implements the following interfaces:
Results return wrapped with a context manager allowing use with async with and async for.
async with aiofiles.tempfile.NamedTemporaryFile('wb+') as f:
await f.write(b'Line1\n Line2')
await f.seek(0)
async for line in f:
print(line)
async with aiofiles.tempfile.TemporaryDirectory() as d:
filename = os.path.join(d, "file.ext")
Real file IO can be mocked by patching aiofiles.threadpool.sync_open
as desired. The return type also needs to be registered with the
aiofiles.threadpool.wrap dispatcher:
aiofiles.threadpool.wrap.register(mock.MagicMock)(
lambda *args, **kwargs: aiofiles.threadpool.AsyncBufferedIOBase(*args, **kwargs)
)
async def test_stuff():
write_data = 'data'
read_file_chunks = [
b'file chunks 1',
b'file chunks 2',
b'file chunks 3',
b'',
]
file_chunks_iter = iter(read_file_chunks)
mock_file_stream = mock.MagicMock(
read=lambda *args, **kwargs: next(file_chunks_iter)
)
with mock.patch('aiofiles.threadpool.sync_open', return_value=mock_file_stream) as mock_open:
async with aiofiles.open('filename', 'w') as f:
await f.write(write_data)
assert f.read() == b'file chunks 1'
mock_file_stream.write.assert_called_once_with(write_data)
os.link conditionally to fix importing on android.
#175aiofiles.os.__all__ when running on Windows.aiofiles.os.path.abspath and aiofiles.os.getcwd.
#174os.statvfs conditionally to fix importing on non-UNIX systems.
#171 #172aiofiles.tempfile.NamedTemporaryFile now accepts a delete_on_close argument, just like the stdlib version.aiofiles.tempfile.NamedTemporaryFile no longer exposes a delete attribute, just like the stdlib version.aiofiles.os.statvfs and aiofiles.os.path.ismount.
#162aiofiles.os.access.
#146aiofiles.tempfile.temptypes.AsyncSpooledTemporaryFile.softspace.
#151aiofiles.stdin, aiofiles.stdin_bytes, and other stdio streams.
#154asyncio.get_running_loop (vs asyncio.get_event_loop) internally.aiofiles.os.path.islink.
#126aiofiles.os.readlink.
#125aiofiles.os.symlink.
#124aiofiles.os.unlink.
#123aiofiles.os.link.
#121aiofiles.os.renames.
#120aiofiles.os.{listdir, scandir}.
#143aiofiles.os.replace.
#107aiofiles.os.{makedirs, removedirs}.aiofiles.os.path.{exists, isfile, isdir, getsize, getatime, getctime, samefile, sameopenfile}.
#63suffix, prefix, dir args to aiofiles.tempfile.TemporaryDirectory.
#116aiofiles.tempfile module for async temporary files.
#56aiofiles is now tested on ppc64le.name and mode properties to async file objects.
#82async/await instead of asyncio.coroutine/yield from).aiofiles.os.remove, aiofiles.os.rename, aiofiles.os.mkdir, aiofiles.os.rmdir.
#62aiofiles.os.sendfile will now work if the standard os module contains a sendfile function.Contributions are very welcome. Tests can be run with tox, please ensure
the coverage at least stays the same before you submit a pull request.
FAQs
File support for asyncio.
We found that aiofiles demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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