aiofiles: file support for asyncio
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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!')
Features
- a file API very similar to Python's standard, blocking API
- support for buffered and unbuffered binary files, and buffered text files
- support for
async
/await
(PEP 492) constructs - async interface to tempfile module
Installation
To install aiofiles, simply:
$ pip install aiofiles
Usage
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:
close
flush
isatty
read
readall
read1
readinto
readline
readlines
seek
seekable
tell
truncate
writable
write
writelines
In 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:
stat
statvfs
sendfile
rename
renames
replace
remove
unlink
mkdir
makedirs
rmdir
removedirs
link
symlink
readlink
listdir
scandir
access
getcwd
path.abspath
path.exists
path.isfile
path.isdir
path.islink
path.ismount
path.getsize
path.getatime
path.getctime
path.samefile
path.sameopenfile
Tempfile
aiofiles.tempfile implements the following interfaces:
- TemporaryFile
- NamedTemporaryFile
- SpooledTemporaryFile
- TemporaryDirectory
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")
Writing tests for aiofiles
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)
History
24.1.0 (2024-06-24)
- Import
os.link
conditionally to fix importing on android.
#175 - Remove spurious items from
aiofiles.os.__all__
when running on Windows. - Switch to more modern async idioms: Remove types.coroutine and make AiofilesContextManager an awaitable instead a coroutine.
- Add
aiofiles.os.path.abspath
and aiofiles.os.getcwd
.
#174 - aiofiles is now tested on Python 3.13 too.
#184
- Dropped Python 3.7 support. If you require it, use version 23.2.1.
23.2.1 (2023-08-09)
- Import
os.statvfs
conditionally to fix importing on non-UNIX systems.
#171 #172 - aiofiles is now also tested on Windows.
23.2.0 (2023-08-09)
- aiofiles is now tested on Python 3.12 too.
#166 #168
- On Python 3.12,
aiofiles.tempfile.NamedTemporaryFile
now accepts a delete_on_close
argument, just like the stdlib version. - On Python 3.12,
aiofiles.tempfile.NamedTemporaryFile
no longer exposes a delete
attribute, just like the stdlib version. - Added
aiofiles.os.statvfs
and aiofiles.os.path.ismount
.
#162 - Use PDM instead of Poetry.
#169
23.1.0 (2023-02-09)
- Added
aiofiles.os.access
.
#146 - Removed
aiofiles.tempfile.temptypes.AsyncSpooledTemporaryFile.softspace
.
#151 - Added
aiofiles.stdin
, aiofiles.stdin_bytes
, and other stdio streams.
#154 - Transition to
asyncio.get_running_loop
(vs asyncio.get_event_loop
) internally.
22.1.0 (2022-09-04)
- Added
aiofiles.os.path.islink
.
#126 - Added
aiofiles.os.readlink
.
#125 - Added
aiofiles.os.symlink
.
#124 - Added
aiofiles.os.unlink
.
#123 - Added
aiofiles.os.link
.
#121 - Added
aiofiles.os.renames
.
#120 - Added
aiofiles.os.{listdir, scandir}
.
#143 - Switched to CalVer.
- Dropped Python 3.6 support. If you require it, use version 0.8.0.
- aiofiles is now tested on Python 3.11.
0.8.0 (2021-11-27)
- aiofiles is now tested on Python 3.10.
- Added
aiofiles.os.replace
.
#107 - Added
aiofiles.os.{makedirs, removedirs}
. - Added
aiofiles.os.path.{exists, isfile, isdir, getsize, getatime, getctime, samefile, sameopenfile}
.
#63 - Added
suffix
, prefix
, dir
args to aiofiles.tempfile.TemporaryDirectory
.
#116
0.7.0 (2021-05-17)
- Added the
aiofiles.tempfile
module for async temporary files.
#56 - Switched to Poetry and GitHub actions.
- Dropped 3.5 support.
0.6.0 (2020-10-27)
aiofiles
is now tested on ppc64le.- Added
name
and mode
properties to async file objects.
#82 - Fixed a DeprecationWarning internally.
#75
- Python 3.9 support and tests.
0.5.0 (2020-04-12)
- Python 3.8 support. Code base modernization (using
async/await
instead of asyncio.coroutine
/yield from
). - Added
aiofiles.os.remove
, aiofiles.os.rename
, aiofiles.os.mkdir
, aiofiles.os.rmdir
.
#62
0.4.0 (2018-08-11)
- Python 3.7 support.
- Removed Python 3.3/3.4 support. If you use these versions, stick to aiofiles 0.3.x.
0.3.2 (2017-09-23)
- The LICENSE is now included in the sdist.
#31
0.3.1 (2017-03-10)
- Introduced a changelog.
aiofiles.os.sendfile
will now work if the standard os
module contains a sendfile
function.
Contributing
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.