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declarative de/serialization of python structures

Project description

As a result of frustration working with colander, I decided to create something similar…

Objective is a de/serialization tool with following features:

  • declarative definition of objectives.
  • no confusion about how to define something, it is always the same.
  • reuse definitions by inheritance.
  • optional validation.
  • make it simple to override certain parts.


Simple mapping and validation

import objective
import datetime

now = datetime.datetime(2001, 9, 11)

class UserObjective(objective.Mapping):

    name = objective.Item(objective.Unicode, missing=objective.Ignore)
    email = objective.Item(objective.Unicode, validator=objective.Email())
    password = objective.Item(objective.Unicode)
    since = objective.Item(objective.UtcDateTime, missing=now)

serialized = {
    'email': '',
    'password': 'foobar'

deserialized = UserObjective.deserialize(serialized)

assert deserialized == {
    'password': u'foobar',
    'email': u'',
    'since': datetime.datetime(2001, 9, 11, 0, 0)

bad_serialized = {
    'name': 'foobar'

    deserialized = UserObjective().deserialize(bad_serialized)

except objective.Invalid as e:

    assert isinstance(e, objective.exc.InvalidChildren)
    assert {(x.node.__name__, x.__class__, x.value) for x in e.children} == {
        ('password', objective.exc.MissingValue, objective.values.Undefined),
        ('email', objective.exc.InvalidValue, 'baz')

Mapping complex structures

import objective

class ProductRequestObjective(objective.BunchMapping):
    class body(objective.Mapping):
        name = objective.Item(objective.Unicode)
        root = objective.Item(objective.Unicode)

        class semantics(objective.List):
            items = objective.Item(objective.Unicode)

    class match(objective.Mapping):
        _id = objective.Item(objective.Field)

Issues, thoughts, ideas

objective is far from complete. There are tons of possible validators I can imagine.

I tried my best (mostly in terms of time) to test.

If you find bugs or you have a great idea, I am totally open to implement it.

Project details

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