Skip to main content

Fast functional serializers

Project description

Strainer is a different take on serialization and validation in python. It utilizes a functional style over classes.

Strainer officially supports Python 2.6–2.7 & 3.4–3.5, and runs great on PyPy.


  • Functional

  • Complex Python object serialization

  • Data de-serialization

  • Data Validation

  • Speed

Serialization Example

import datetime
from strainer import (serializer, field, child,
                      formatters, validators,

artist_serializer = serializer(
  field('name', validators=[validators.required()])

album_schema = serializer(
  field('title', validators=[validators.required()]),
        validators=[validators.required(), validators.datetime()],
  child('artist', serializer=artist_serializer, validators=[validators.required()])

class Artist(object):
    def __init__(self, name): = name

class Album(object):
    def __init__(self, title, release_date, artist):
        self.title = title
        self.release_date = release_date
        self.artist = artist

bowie = Artist(name='David Bowie')
album = Album(
    title='Hunky Dory',
    release_date=datetime.datetime(1971, 12, 17)

Now we can serialize, deserialize, and validate data

>>> album_schema.serialize(album)
{'artist': {'name': 'David Bowie'},
 'release_date': '1971-12-17T00:00:00',
 'title': 'Hunky Dory'}
>>> album_schema.deserialize(album_schema.serialize(album))
{'artist': {'name': 'David Bowie'},
 'release_date': datetime.datetime(1971, 12, 17, 0, 0, tzinfo=<iso8601.Utc>),
 'title': 'Hunky Dory'}
>>> input = album_schema.serialize(album)
>>> del input['artist']
>>> album_schema.deserialize(input)
ValidationException: {'artist': ['This field is required']}

The example has been borrowed from Marshmallow and tweaked.


To install Strainer, simply:

$ pip install pystrainer

Satisfaction, guaranteed.

Release History


  • refining validators

  • added attr_getter to child, and many


  • Updating docs

  • Making it official


  • Fixing python 3 comptatability issue


  • Removed an errant print statement


  • Fixed a bug with datetime validators


  • Fixed a bug with multiple validation, pointing to the correct index

  • Fixed a bug that applied vlaidation to entire array in multiple instead of elements

  • Added a dict_field, if source is dict, instead of an object

  • Added ability to pass validators to child, and many instances applying validation before moving to sub-element

  • Added tests around catching nested validation errors

  • Added formatters, so things can be formatted on the way out

  • Got rid of encoders, not the domain of this project

  • Everything can be imported from one namespace

  • Changed the API from to_representation/to_internal to serialize/deserialize

0.0.5 (2016-11-29)

  • Fleshed out docs

  • Added datetime validator

  • Increased speed bu reducing loops

0.0.4 (2016-11-23)

  • Add some validators

0.0.1 (2016-11-23)

  • Birth

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

pystrainer-1.3.1.tar.gz (7.5 kB view hashes)

Uploaded Source

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page