Pythonic implementation of Golang's (un)marshalling of structs to/from various data serialization formats
Project description
PyMarshal
pymarshal replicates the feature of (un)marshalling structs in Golang. Rather than attempting to replicate the exact feature as it exists in Go, pymarshal aims for elegant, Pythonic simplicity, and to fix the flaws in Go's implementation such as:
- extra keys being silently ignored
- lack of mandatory fields
- lack of default values
Beyond fixing the flaws of Golang's implementation:
- The design of PyMarshal encourages writing unit testable code
- Integrated API documentation
Currently supported serialization formats
As YAML is compatible with JSON, use PyYAML to load or dump data
with the pymarshal.json
module, there is no explicit YAML module.
Installation
It is recommended that you install
from PyPI
using pip install pymarshal
pymarshal is compatible with Python2.7, and Python3.x
CLICK HERE for an example of a modern REST API that uses PyMarshal
Overview
The only modification required to your class code is to use the type_assert
functions to assign __init__
arguments to self variables of the same
name. pymarshal provides the type_assert
functions to both enforce the type,
and to unmarshal nested objects.
Example (including the YAML-based docstring for API docs):
class MyModel:
def __init__(
self,
a,
b=5,
):
"""
desc: >
An example model
Blah blah, blah blah
args:
- name: a
type: str
desc: The a thing
- name: b
type: str
desc: The b thing
required: false
default: 5
"""
self.a = type_assert(a, str)
self.b = type_assert(b, int)
>>> from pymarshal.json import *
>>> x = marshal_json(MyModel("test", 6))
>>> x
{"a": "test", "b": 6}
>>> y = unmarshal_json(x, MyModel)
>>> y.a
"test"
NOTE: Your classes must not implement __call__
(which is an antipattern
anyway). Whatever you would've implemented with __call__
should just be
a normal, named method.
Your __init__
methods should only use simple assignment through the
type_assert
functions. If you have a use-case for a constructor that
does more than simple assignment, use a separate
'factory' static method.
There is also:
type_assert_iter
for iterablestype_assert_dict
for anything that implements .items() -> k, v
Rather than using the Golang "tag" syntax, simply create a
_marshal_key_swap
and _unmarshal_key_swap
dict in your class,
and any re-named keys will be swapped before being passed to the
class constructor or before being marshalled to JSON. The full list
of control variables are documented
HERE.
Examples
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