Strainer: Fast Functional Serializers¶

Strainer is a different take on object serialization and validation in python.

It utilizes a functional style over classes.

A Strainer Example

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

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

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

class Artist(object):
    def __init__(self, name):
        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(
    artist=bowie,
    title='Hunky Dory',
    release_date=datetime.datetime(1971, 12, 17)
)

Given that we can now 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