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Pythonic implementation of Golang's (un)marshalling of structs to/from various data serialization formats

Project description


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


Support for the YAML API doc format has been dropped. If you need this, use 1.6.2

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.


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


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.


class MyModel:
    def __init__(
        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

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 iterables
  • type_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.



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