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A lightweight library for converting complex datatypes into native Python datatypes.

Project description

Latest version Travis-CI


marshmallow is an ORM/ODM/framework-agnostic library for converting complex datatypes, such as objects, into native Python datatypes. The serialized objects can then be rendered to standard formats such as JSON for use in a REST API.

from datetime import datetime
from marshmallow import Serializer, fields

# A "model"
class Person(object):
    def __init__(self, name): = name
        self.date_born =

# A serializer
class PersonSerializer(Serializer):
    name = fields.String()
    date_born = fields.DateTime()

person = Person("Guido van Rossum")
serialized = PersonSerializer(person)
# {"name": "Guido van Rossum", "date_born": "Sun, 10 Nov 2013 14:24:50 -0000"}

Get It Now

$ pip install -U marshmallow


Full documentation is available at .


  • Python >= 2.6 or >= 3.3


MIT licensed. See the bundled LICENSE file for more details.


0.3.1 (2013-11-16)

  • Fix bug with serializing dictionaries.
  • Fix error raised when serializing empty list.
  • Add only and exclude parameters to Serializer constructor.
  • Add strict parameter and option: causes Serializer to raise an error if invalid data are passed in, rather than storing errors.
  • Updated Flask + SQLA example in docs.

0.3.0 (2013-11-14)

  • Declaring Serializers just got easier. The class Meta paradigm allows you to specify fields more concisely. Can specify fields and exclude options.
  • Allow date formats to be changed by passing format parameter to DateTime field constructor. Can either be "rfc" (default), "iso", or a date format string.
  • More useful error message when declaring fields as classes (instead of an instance, which is the correct usage).
  • Rename MarshallingException -> MarshallingError.
  • Rename marshmallow.core -> marshmallow.serializer.

0.2.1 (2013-11-12)

  • Allow prefixing field names.
  • Fix storing errors on Nested Serializers.
  • Python 2.6 support.

0.2.0 (2013-11-11)

  • Field-level validation.
  • Add fields.Method.
  • Add fields.Function.
  • Allow binding of extra data to a serialized object by passing the extra param when initializing a Serializer.
  • Add relative paramater to fields.Url that allows for relative URLs.

0.1.0 (2013-11-10)

  • First release.

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