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Metadata-Version: 2.1
Name: msgpack
Version: 1.0.7
Summary: MessagePack serializer
Author-email: Inada Naoki <songofacandy@gmail.com>
License: Apache 2.0
Project-URL: Homepage, https://msgpack.org/
Project-URL: Documentation, https://msgpack-python.readthedocs.io/
Project-URL: Repository, https://github.com/msgpack/msgpack-python/
Project-URL: Tracker, https://github.com/msgpack/msgpack-python/issues
Project-URL: Changelog, https://github.com/msgpack/msgpack-python/blob/main/ChangeLog.rst
Keywords: msgpack,messagepack,serializer,serialization,binary
Classifier: Development Status :: 5 - Production/Stable
Classifier: Operating System :: OS Independent
Classifier: Programming Language :: Python
Classifier: Programming Language :: Python :: 3
Classifier: Programming Language :: Python :: 3.8
Classifier: Programming Language :: Python :: 3.9
Classifier: Programming Language :: Python :: 3.10
Classifier: Programming Language :: Python :: 3.11
Classifier: Programming Language :: Python :: 3.12
Classifier: Programming Language :: Python :: Implementation :: CPython
Classifier: Programming Language :: Python :: Implementation :: PyPy
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: Apache Software License
Requires-Python: >=3.8
Description-Content-Type: text/markdown
License-File: COPYING
# MessagePack for Python
[](https://github.com/msgpack/msgpack-python/actions/workflows/wheel.yml)
[](https://msgpack-python.readthedocs.io/en/latest/?badge=latest)
## What's this
[MessagePack](https://msgpack.org/) is an efficient binary serialization format.
It lets you exchange data among multiple languages like JSON.
But it's faster and smaller.
This package provides CPython bindings for reading and writing MessagePack data.
## Very important notes for existing users
### PyPI package name
Package name on PyPI was changed from `msgpack-python` to `msgpack` from 0.5.
When upgrading from msgpack-0.4 or earlier, do `pip uninstall msgpack-python` before
`pip install -U msgpack`.
### Compatibility with the old format
You can use `use_bin_type=False` option to pack `bytes`
object into raw type in the old msgpack spec, instead of bin type in new msgpack spec.
You can unpack old msgpack format using `raw=True` option.
It unpacks str (raw) type in msgpack into Python bytes.
See note below for detail.
### Major breaking changes in msgpack 1.0
* Python 2
* The extension module does not support Python 2 anymore.
The pure Python implementation (`msgpack.fallback`) is used for Python 2.
* Packer
* `use_bin_type=True` by default. bytes are encoded in bin type in msgpack.
**If you are still using Python 2, you must use unicode for all string types.**
You can use `use_bin_type=False` to encode into old msgpack format.
* `encoding` option is removed. UTF-8 is used always.
* Unpacker
* `raw=False` by default. It assumes str types are valid UTF-8 string
and decode them to Python str (unicode) object.
* `encoding` option is removed. You can use `raw=True` to support old format.
* Default value of `max_buffer_size` is changed from 0 to 100 MiB.
* Default value of `strict_map_key` is changed to True to avoid hashdos.
You need to pass `strict_map_key=False` if you have data which contain map keys
which type is not bytes or str.
## Install
```
$ pip install msgpack
```
### Pure Python implementation
The extension module in msgpack (`msgpack._cmsgpack`) does not support
Python 2 and PyPy.
But msgpack provides a pure Python implementation (`msgpack.fallback`)
for PyPy and Python 2.
### Windows
When you can't use a binary distribution, you need to install Visual Studio
or Windows SDK on Windows.
Without extension, using pure Python implementation on CPython runs slowly.
## How to use
NOTE: In examples below, I use `raw=False` and `use_bin_type=True` for users
using msgpack < 1.0. These options are default from msgpack 1.0 so you can omit them.
### One-shot pack & unpack
Use `packb` for packing and `unpackb` for unpacking.
msgpack provides `dumps` and `loads` as an alias for compatibility with
`json` and `pickle`.
`pack` and `dump` packs to a file-like object.
`unpack` and `load` unpacks from a file-like object.
```pycon
>>> import msgpack
>>> msgpack.packb([1, 2, 3], use_bin_type=True)
'\x93\x01\x02\x03'
>>> msgpack.unpackb(_, raw=False)
[1, 2, 3]
```
`unpack` unpacks msgpack's array to Python's list, but can also unpack to tuple:
```pycon
>>> msgpack.unpackb(b'\x93\x01\x02\x03', use_list=False, raw=False)
(1, 2, 3)
```
You should always specify the `use_list` keyword argument for backward compatibility.
See performance issues relating to `use_list option`_ below.
Read the docstring for other options.
### Streaming unpacking
`Unpacker` is a "streaming unpacker". It unpacks multiple objects from one
stream (or from bytes provided through its `feed` method).
```py
import msgpack
from io import BytesIO
buf = BytesIO()
for i in range(100):
buf.write(msgpack.packb(i, use_bin_type=True))
buf.seek(0)
unpacker = msgpack.Unpacker(buf, raw=False)
for unpacked in unpacker:
print(unpacked)
```
### Packing/unpacking of custom data type
It is also possible to pack/unpack custom data types. Here is an example for
`datetime.datetime`.
```py
import datetime
import msgpack
useful_dict = {
"id": 1,
"created": datetime.datetime.now(),
}
def decode_datetime(obj):
if '__datetime__' in obj:
obj = datetime.datetime.strptime(obj["as_str"], "%Y%m%dT%H:%M:%S.%f")
return obj
def encode_datetime(obj):
if isinstance(obj, datetime.datetime):
return {'__datetime__': True, 'as_str': obj.strftime("%Y%m%dT%H:%M:%S.%f")}
return obj
packed_dict = msgpack.packb(useful_dict, default=encode_datetime, use_bin_type=True)
this_dict_again = msgpack.unpackb(packed_dict, object_hook=decode_datetime, raw=False)
```
`Unpacker`'s `object_hook` callback receives a dict; the
`object_pairs_hook` callback may instead be used to receive a list of
key-value pairs.
### Extended types
It is also possible to pack/unpack custom data types using the **ext** type.
```pycon
>>> import msgpack
>>> import array
>>> def default(obj):
... if isinstance(obj, array.array) and obj.typecode == 'd':
... return msgpack.ExtType(42, obj.tostring())
... raise TypeError("Unknown type: %r" % (obj,))
...
>>> def ext_hook(code, data):
... if code == 42:
... a = array.array('d')
... a.fromstring(data)
... return a
... return ExtType(code, data)
...
>>> data = array.array('d', [1.2, 3.4])
>>> packed = msgpack.packb(data, default=default, use_bin_type=True)
>>> unpacked = msgpack.unpackb(packed, ext_hook=ext_hook, raw=False)
>>> data == unpacked
True
```
### Advanced unpacking control
As an alternative to iteration, `Unpacker` objects provide `unpack`,
`skip`, `read_array_header` and `read_map_header` methods. The former two
read an entire message from the stream, respectively de-serialising and returning
the result, or ignoring it. The latter two methods return the number of elements
in the upcoming container, so that each element in an array, or key-value pair
in a map, can be unpacked or skipped individually.
## Notes
### string and binary type
Early versions of msgpack didn't distinguish string and binary types.
The type for representing both string and binary types was named **raw**.
You can pack into and unpack from this old spec using `use_bin_type=False`
and `raw=True` options.
```pycon
>>> import msgpack
>>> msgpack.unpackb(msgpack.packb([b'spam', 'eggs'], use_bin_type=False), raw=True)
[b'spam', b'eggs']
>>> msgpack.unpackb(msgpack.packb([b'spam', 'eggs'], use_bin_type=True), raw=False)
[b'spam', 'eggs']
```
### ext type
To use the **ext** type, pass `msgpack.ExtType` object to packer.
```pycon
>>> import msgpack
>>> packed = msgpack.packb(msgpack.ExtType(42, b'xyzzy'))
>>> msgpack.unpackb(packed)
ExtType(code=42, data='xyzzy')
```
You can use it with `default` and `ext_hook`. See below.
### Security
To unpacking data received from unreliable source, msgpack provides
two security options.
`max_buffer_size` (default: `100*1024*1024`) limits the internal buffer size.
It is used to limit the preallocated list size too.
`strict_map_key` (default: `True`) limits the type of map keys to bytes and str.
While msgpack spec doesn't limit the types of the map keys,
there is a risk of the hashdos.
If you need to support other types for map keys, use `strict_map_key=False`.
### Performance tips
CPython's GC starts when growing allocated object.
This means unpacking may cause useless GC.
You can use `gc.disable()` when unpacking large message.
List is the default sequence type of Python.
But tuple is lighter than list.
You can use `use_list=False` while unpacking when performance is important.