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marshmallow 0.5.2

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

Latest Version: 3.0.0b6


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, pprint

# 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

marshmallow has no external dependencies outside of the Python standard library.


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


0.5.2 (2014-02-10)

  • Enable custom field validation via the validate parameter.
  • Add utils.from_rfc for parsing RFC datestring to Python datetime object.

0.5.1 (2014-02-02)

  • Avoid unnecessary attribute access in utils.to_marshallable_type for improved performance.
  • Fix RFC822 formatting for localized datetimes.

0.5.0 (2013-12-29)

  • Can customize validation error messages by passing the error parameter to a field.
  • Backwards-incompatible: Rename fields.NumberField -> fields.Number.
  • Add fields.Select. Thanks @ecarreras.
  • Support nesting a Serializer within itself by passing "self" into fields.Nested (only up to depth=1).
  • Backwards-incompatible: No implicit serializing of collections. Must set many=True if serializing to a list. This ensures that marshmallow handles singular objects correctly, even if they are iterable.
  • If Nested field only parameter is a field name, only return a single value for the nested object (instead of a dict) or a flat list of values.
  • Improved performance and stability.

0.4.1 (2013-12-01)

  • An object’s __marshallable__ method, if defined, takes precedence over __getitem__.
  • Generator expressions can be passed to a serializer.
  • Better support for serializing list-like collections (e.g. ORM querysets).
  • Other minor bugfixes.

0.4.0 (2013-11-24)

  • Add additional clas Meta option.
  • Add dateformat class Meta option.
  • Support for serializing UUID, date, time, and timedelta objects.
  • Remove Serializer.to_data method. Just use property.
  • String field defaults to empty string instead of None.
  • Backwards-incompatible: isoformat and rfcformat functions moved to
  • Backwards-incompatible: Validation functions moved to
  • Backwards-incompatible: Remove
  • Reorder parameters to DateTime field (first parameter is dateformat).
  • Ensure that to_json returns bytestrings.
  • Fix bug with including an object property in fields Meta option.
  • Fix bug with passing None to a serializer.

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.
File Type Py Version Uploaded on Size
marshmallow-0.5.2-py2.py3-none-any.whl (md5) Python Wheel 2.7 2014-02-10 24KB
marshmallow-0.5.2.tar.gz (md5) Source 2014-02-10 19KB