Changelogs » Marshmallow

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Marshmallow

3.15.0

*******************
  
  * Address distutils deprecation warning in Python 3.10 (:pr:`1903`).
  Thanks :user:`kkirsche` for the PR.

3.14.1

*******************
  
  Bug fixes:
  
  - Fix publishing type hints per `PEP-561 <https://www.python.org/dev/peps/pep-0561/>`_.
  Thanks :user:`bwindsor` for the catch and patch.

3.14.0

*******************
  
  Bug fixes:
  
  - Fix ``fields.TimeDelta`` serialization precision (:issue:`1865`).
  Thanks :user:`yarsanich` for reporting.
  
  Other changes:
  
  - Fix type-hints for data arg in Schema.validate to accept
  list of dictionaries (:issue:`1790`, :pr:`1868`).
  Thanks  :user:`yourun-proger` for PR.
  - Improve warning when passing metadata as keyword arguments (:pr:`1882`).
  Thanks :user:`traherom` for the PR.
  - Don't build universal wheels. We don't support Python 2 anymore.
  (:issue:`1860`) Thanks :user:`YKdvd` for reporting.
  - Make the build reproducible (:pr:`1862`).
  - Drop support for Python 3.5 (:pr:`1863`).
  - Test against Python 3.10 (:pr:`1888`).

3.13.0

*******************
  
  Features:
  
  - Replace ``missing``/``default`` field parameters with
  ``load_default``/``dump_default`` (:pr:`1742`).
  Thanks :user:`sirosen` for the PR.
  
  Deprecations:
  
  - The use of ``missing``/``default`` field parameters is deprecated and will be
  removed in marshmallow 4. ``load_default``/``dump_default`` should be used
  instead.

3.12.2

*******************
  
  Bug fixes:
  
  - Don't expose ``Field``\s as ``Schema`` attributes. This reverts a change
  introduced in 3.12.0 that causes issues when field names conflict with
  ``Schema`` attributes or methods. ``Fields``\s are still accessible on a
  ``Schema`` instance throught the ``fields`` attribute. (:pr:`1843`)

3.12.1

*******************
  
  Bug fixes:
  
  - Fix bug that raised an ``AttributeError`` when instantiating a
  ``Schema`` with a field named ``parent`` (:issue:`1808`).
  Thanks :user:`flying-sheep` for reporting and helping with the fix.

3.12.0

*******************
  
  Features:
  
  - Add ``validate.And`` (:issue:`1768`).
  Thanks :user:`rugleb` for the suggestion.
  - Add type annotations to ``marshmallow.decorators`` (:issue:`1788`, :pr:`1789`).
  Thanks :user:`michaeldimchuk` for the PR.
  - Let ``Field``\s be accessed by name as ``Schema`` attributes (:pr:`1631`).
  
  Other changes:
  
  - Improve types in ``marshmallow.validate`` (:pr:`1786`).
  - Make ``marshmallow.validate.Validator`` an abstract base class (:pr:`1786`).
  - Remove unnecessary list cast (:pr:`1785`).

3.11.1

*******************
  
  Bug fixes:
  
  - Fix treatment of dotted keys when ``unknown=INCLUDE`` (:issue:`1506`).
  Thanks :user:`rbu` for reporting and thanks :user:`sirosen` for the fix (:pr:`1745`).

3.11.0

*******************
  
  Features:
  
  - Add ``fields.IPInterface``, ``fields.IPv4Interface``, and
  ``IPv6Interface`` (:issue:`1733`). Thanks :user:`madeinoz67`
  for the suggestion and the PR.
  - Raise ``AttributeError`` for missing methods when using ``fields.Method`` (:pr:`1675`).
  Thanks :user:`lassandroan`.
  
  Other changes:
  
  - Remove unnecessary ``hasattr`` and ``getattr`` checks in ``Field`` (:pr:`1770`).

3.10.0

*******************
  
  Deprecations:
  
  - Passing field metadata via keyword arguments is deprecated and will be
  removed in marshmallow 4 (:issue:`1350`). Use the explicit ``metadata=...``
  argument instead. Thanks :user:`sirosen`.

3.9.1

******************
  
  Bug fixes:
  
  - Cast to mapping type in ``Mapping.serialize`` and ``Mapping.deserialize``
  (:pr:`1685`).
  - Fix bug letting ``Dict`` pass invalid dict on deserialization when no key or
  value ``Field`` is specified (:pr:`1685`).

3.9.0

******************
  
  Features:
  
  - Add ``format`` argument to ``fields.Time`` and ``timeformat`` ``class Meta`` option (:issue:`686`).
  Thanks :user:`BennyAlex` for the suggestion and thanks :user:`infinityxxx` for the PR.
  
  Other changes:
  
  - Remove usage of implicit ``typing.Optional`` (:issue:`1663`).
  Thanks :user:`nadega` for the PR.

3.8.0

******************
  
  Features:
  
  - Add ``fields.IP``, ``fields.IPv4`` and ``fields.IPv6`` (:pr:`1485`). Thanks
  :user:`mgetka` for the PR.
  
  Bug fixes:
  
  - Fix typing in ``AwareDateTime`` (:pr:`1658`). Thanks :user:`adithyabsk` for
  reporting.

3.7.1

******************
  
  Bug fixes:
  
  - ``fields.Boolean`` correctly serializes non-hashable types (:pr:`1633`).
  Thanks :user:`jun0jang` for the PR.

3.7.0

******************
  
  Deprecations:
  
  - ``marshmallow.pprint`` is deprecated and will be removed in marshmallow 4 (:issue:`1588`).
  
  Support:
  
  - Document ``default_error_messages`` on field classes (:pr:`1619`). Thanks :user:`weeix`.
  
  Bug fixes:
  
  - Fix passing ``only`` and ``exclude`` to ``Nested`` with an ordered ``Schema`` (:pr:`1627`).
  Thanks :user:`juannorris` for the PR.

3.6.1

******************
  
  No code changes--only docs and contributor-facing updates in this release.
  
  Support:
  
  - Documentation: improve custom fields example (:issue:`1538`).
  Thanks :user:`pablospizzamiglio` for reporting the problem with the
  old example and thanks :user:`Resinderate` for the PR.
  - Documentation: Split up API reference into multiple pages and
  add summary tables (:pr:`1587`). Thanks :user:`EpicWink` for the PR.

3.6.0

******************
  
  Features:
  
  - Add ``validate.ContainsNoneOf`` (:issue:`1528`).
  Thanks :user:`Resinderate` for the suggestion and the PR.

3.5.2

******************
  
  Bug fixes:
  
  - Fix typing in ``class_registry`` (:pr:`1574`). Thanks :user:`mahenzon`.

3.5.1

******************
  
  Bug fixes:
  
  - Includes bug fix from 2.21.0.

3.5.0

******************
  
  Bug fixes:
  
  - Fix list of nullable nested fields ``List(Nested(Field, allow_none=True)``
  (:issue:`1497`). Because this fix reverts an optimization introduced to
  speed-up serialization and deserialization of lists of nested fields, a
  negative impact on performance in this specific case is expected.

3.4.0

******************
  
  Features:
  
  - Improve type coverage (:issue:`1479`). Thanks :user:`Reskov`.
  
  Bug fixes:
  
  - Fix typing for ``data`` param of ``Schema.load`` and ``ValidationError`` (:issue:`1492`).
  Thanks :user:`mehdigmira` for reporting and thanks :user:`dfirst` for the PR.
  
  Other changes:
  
  - Remove unnecessary typecasts (:pr:`1500`). Thanks :user:`hukkinj1`.
  - Remove useless ``_serialize`` override in ``UUID`` field (:pr:`1489`).

3.3.0

******************
  
  Features:
  
  - ``fields.Nested`` may take a callable that returns a schema instance.
  Use this to resolve order-of-declaration issues when schemas nest each other (:issue:`1146`).
  
  .. code-block:: python
  
  <3.3
  class AlbumSchema(Schema):
  title = fields.Str()
  artist = fields.Nested("ArtistSchema", only=("name",))
  
  
  class ArtistSchema(Schema):
  name = fields.Str()
  albums = fields.List(fields.Nested(AlbumSchema))
  
  
  >=3.3
  class AlbumSchema(Schema):
  title = fields.Str()
  artist = fields.Nested(lambda: ArtistSchema(only=("name",)))
  
  
  class ArtistSchema(Schema):
  name = fields.Str()
  albums = fields.List(fields.Nested(AlbumSchema))
  
  Deprecations:
  
  - Passing the string ``"self"`` to ``fields.Nested`` is deprecated.
  Use a callable instead.
  
  .. code-block:: python
  
  from marshmallow import Schema, fields
  
  <3.3
  class PersonSchema(Schema):
  partner = fields.Nested("self", exclude=("partner",))
  friends = fields.List(fields.Nested("self"))
  
  
  >=3.3
  class PersonSchema(Schema):
  partner = fields.Nested(lambda: PersonSchema(exclude=("partner")))
  friends = fields.List(fields.Nested(lambda: PersonSchema()))
  
  Other changes:
  
  - Fix typing for ``Number._format_num`` (:pr:`1466`). Thanks :user:`hukkinj1`.
  - Make mypy stricter and remove dead code (:pr:`1467`). Thanks again, :user:`hukkinj1`.

3.2.2

******************
  
  Bug fixes:
  
  - Don't load fields for which ``load_only`` and ``dump_only`` are both ``True`` (:pr:`1448`).
  - Fix types in ``marshmallow.validate`` (:pr:`1446`).
  
  Support:
  
  - Test against Python 3.8 (:pr:`1431`).

3.2.1

++++++++++++++++++
  
  Bug fixes:
  
  - Fix typing for ``Schema.dump[s]`` (:pr:`1416`).

3.2.0

++++++++++++++++++
  
  Features:
  
  - Add type annotations to ``marshmallow.schema`` and ``marshmallow.validate`` (:pr:`1407`, :issue:`663`).
  
  Bug fixes:
  
  - Fix compatibility with Python < 3.5.3 (:issue:`1409`). Thanks :user:`lukaszdudek-silvair` for reporting.
  
  Refactoring:
  
  - Remove unnecessary ``BaseSchema`` superclass (:pr:`1406`).

3.1.1

++++++++++++++++++
  
  Bug fixes:
  
  - Restore inheritance hierarchy of ``Number`` fields (:pr:`1403`).
  ``fields.Integer`` and ``fields.Decimal`` inherit from ``fields.Number``.
  - Fix bug that raised an uncaught error when a nested schema instance had an unpickleable object in its context (:issue:`1404`).
  Thanks :user:`metheoryt` for reporting.

3.1.0

++++++++++++++++++
  
  Features:
  
  - Add more type annotations (:issue:`663`).
  Type information is distributed per `PEP 561 <https://www.python.org/dev/peps/pep-0561/>`_ .
  Thanks :user:`fuhrysteve` for helping with this.
  
  Bug fixes:
  
  - Includes bug fix from 2.20.5.

3.0.5

++++++++++++++++++
  
  Bug fixes:
  
  - Fix bug that raised an uncaught error when passing both a schema instance and ``only`` to ``Nested`` (:pr:`1395`).
  This bug also affected passing a schema instance to ``fields.Pluck``.

3.0.4

++++++++++++++++++
  
  Bug fixes:
  
  - Fix propagating dot-delimited ``only`` and ``exclude`` parameters to nested schema instances (:issue:`1384`).
  - Includes bug fix from 2.20.4 (:issue:`1160`).

3.0.3

++++++++++++++++++
  
  Bug fixes:
  
  - Handle when ``data_key`` is an empty string (:issue:`1378`).
  Thanks :user:`jtrakk` for reporting.

3.0.2

++++++++++++++++++
  
  Bug fixes:
  
  - Includes bug fix from 2.20.3 (:pr:`1376`).
  - Fix incorrect ``super()`` call in ``SchemaMeta.__init__`` (:pr:`1362`).

3.0.1

++++++++++++++++++
  
  Bug fixes:
  
  - Fix bug when nesting ``fields.DateTime`` within ``fields.List`` or ``fields.Tuple`` (:issue:`1357`).
  This bug was introduced in 3.0.0rc9. Thanks :user:`zblz` for reporting.

3.0.0

++++++++++++++++++
  
  Features:
  
  - Optimize ``List(Nested(...))`` (:issue:`779`).
  - Minor performance improvements and cleanup (:pr:`1328`).
  - Add ``Schema.from_dict`` (:issue:`1312`).
  
  Deprecations/Removals:
  
  - ``Field.fail`` is deprecated. Use ``Field.make_error`` instead.
  - Remove UUID validation from ``fields.UUID``, for consistency with other fields (:issue:`1132`).
  
  Support:
  
  - Various docs improvements (:pr:`1329`).

3.0.0rc9

+++++++++++++++++++++
  
  Features:
  
  - *Backwards-incompatible*: Validation does not occur on serialization (:issue:`1132`).
  This significantly improves serialization performance.
  - *Backwards-incompatible*: ``DateTime`` does not affect timezone information
  on serialization and deserialization (:issue:`1234`, :pr:`1278`).
  - Add ``NaiveDateTime`` and ``AwareDateTime`` to enforce timezone awareness
  (:issue:`1234`, :pr:`1287`).
  - *Backwards-incompatible*: ``List`` does not wrap single values in a list on
  serialization (:pr:`1307`).
  - *Backwards-incompatible*: ``Schema.handle_error`` receives ``many`` and ``partial`` as keyword arguments (:pr:`1321`).
  - Use ``raise from`` more uniformly to improve stack traces (:pr:`1313`).
  - Rename ``Nested.__schema`` to ``Nested._schema`` to prevent name mangling (:issue:`1289`).
  - Performance improvements (:pr:`1309`).
  
  Deprecations/Removals:
  
  - ``LocalDateTime`` is removed (:issue:`1234`).
  - ``marshmallow.utils.utc`` is removed. Use ``datetime.timezone.utc`` instead.
  
  Bug fixes:
  
  - Fix behavior of ``List(Nested("self"))`` (`779 (comment) <https://github.com/marshmallow-code/marshmallow/issues/779#issuecomment-396354987>`_).
  
  Support:
  
  - Document usage of ``validate.Regexp``'s usage ``re.search`` (:issue:`1285`). Thanks :user:`macdonaldezra`.

3.0.0rc8

+++++++++++++++++++++
  
  Features:
  
  - Propagate ``only`` and ``exclude`` parameters to ``Nested`` fields
  within ``List`` and ``Dict`` (:issue:`779`, :issue:`946`).
  - Use ``email.utils.parsedate_to_datetime`` instead of conditionally
  using dateutil for parsing RFC dates (:pr:`1246`).
  - Use internal util functions instead of conditionally using dateutil
  for parsing  ISO 8601 datetimes, dates and times. Timezone info is now
  correctly deserialized whether or not dateutil is installed. (:pr:`1265`)
  - Improve error messages for ``validate.Range``.
  - Use ``raise from error`` for better stack traces (:pr:`1254`). Thanks
  :user:`fuhrysteve`.
  - python-dateutil is no longer used. This resolves the inconsistent behavior
  based on the presence of python-dateutil (:issue:`497`, :issue:`1234`).
  
  Bug fixes:
  
  - Fix method resolution for ``__init__`` method of ``fields.Email`` and
  ``fields.URL`` (:issue:`1268`). Thanks :user:`dursk` for the catch and patch.
  - Includes bug fixes from 2.19.4 and 2.19.5.
  
  Other changes:
  
  - *Backwards-incompatible*: Rename ``fields.List.container`` to ``fields.List.inner``,
  ``fields.Dict.key_container`` to ``fields.Dict.key_field``, and
  ``fields.Dict.value_container`` to ``fields.Dict.value_field``.
  - Switch to Azure Pipelines for CI (:issue:`1261`).

3.0.0rc7

+++++++++++++++++++++
  
  Features:
  
  - *Backwards-incompatible*: ``many`` is passed as a keyword argument to methods decorated with
  ``pre_load``, ``post_load``, ``pre_dump``, ``post_dump``,
  and ``validates_schema``. ``partial`` is passed as a keyword argument to
  methods decorated with ``pre_load``, ``post_load`` and ``validates_schema``.
  ``**kwargs`` should be added to all decorated methods.
  - Add ``min_inclusive`` and ``max_exclusive`` parameters to
  ``validate.Range`` (:issue:`1221`). Thanks :user:`kdop` for the PR.
  
  Bug fixes:
  
  - Fix propagation of ``partial`` to ``Nested`` containers (part of :issue:`779`).
  - Includes bug fix from 2.19.3.
  
  Other changes:
  
  - *Backwards-incompatible*: Use keyword-only arguments (:issue:`1216`).

3.0.0rc6

+++++++++++++++++++++
  
  Support:
  
  - *Backwards-incompatible*: Remove support for Python 2 (:issue:`1120`).
  Only Python>=3.5 is supported.
  Thank you :user:`rooterkyberian` for the suggestion and the PR.
  - *Backwards-incompatible*: Remove special-casing in ``fields.List`` and
  ``fields.Tuple`` for accessing nested attributes (:pr:`1188`).
  Use ``fields.List(fields.Pluck(...))`` instead.
  - Add ``python_requires`` to ``setup.py`` (:pr:`1194`).
  Thanks :user:`hugovk`.
  - Upgrade syntax with ``pyupgrade`` in pre-commit (:pr:`1195`). Thanks
  again :user:`hugovk`.

3.0.0rc5

+++++++++++++++++++++
  
  Features:
  
  - Allow input value to be included in error messages
  for a number of fields (:pr:`1129`). Thanks :user:`hdoupe` for the PR.
  - Improve default error messages for ``OneOf`` and ``ContainsOnly``
  (:issue:`885`). Thanks :user:`mcgfeller` for the suggestion
  and :user:`maxalbert` for the PR.
  
  Deprecations/Removals:
  
  - Remove ``fields.FormattedString`` (:issue:`1141`). Use
  ``fields.Function`` or ``fields.Method`` instead.
  
  Bug fixes:
  
  - Includes bug fix from 2.19.2.

3.0.0rc4

+++++++++++++++++++++
  
  Features:
  
  - Add ``fields.Tuple`` (:issue:`1103`) Thanks :user:`zblz` for the PR.
  - Add ``fields.Mapping``, which makes it easier to support other
  mapping types (e.g. ``OrderedDict``)  (:issue:`1092`).
  Thank :user:`sayanarijit` for the suggestion and the PR.

3.0.0rc3

+++++++++++++++++++++
  
  Features:
  
  - Make the error messages for "unknown fields" and "invalid data type"
  configurable (:issue:`852`). Thanks :user:`Dunstrom` for the PR.
  - ``fields.Boolean`` parses ``"yes"``/``"no"`` values (:pr:`1081`).
  Thanks :user:`r1b`.
  
  Other changes:
  
  - *Backwards-incompatible with previous 3.x versions*: Change ordering
  of ``keys`` and ``values`` arguments to ``fields.Dict``.
  - Remove unused code in ``marshmallow.utils``: ``is_indexable_but_not_string``,
  ``float_to_decimal``, ``decimal_to_fixed``, ``from_iso`` (:pr:`1088`).
  - Remove unused ``marshmallow.compat.string_types``.
  
  Bug fixes:
  
  - Includes bug fix from 2.18.0.

3.0.0rc2

+++++++++++++++++++++
  
  Features:
  
  - Add ``register`` *class Meta* option to allow bypassing marshmallow's
  internal class registry when memory usage is critical (:issue:`660`).
  
  Bug fixes:
  
  - Fix serializing dict-like objects with properties (:issue:`1060`).
  Thanks :user:`taion` for the fix.
  - Fix populating ``ValidationError.valid_data`` for ``List`` and
  ``Dict`` fields (:issue:`766`).
  
  Other changes:
  
  - Add ``marshmallow.__version_info__`` (:pr:`1074`).
  - Remove the ``marshmallow.marshalling`` internal module (:pr:`1070`).
  - A ``ValueError`` is raised when the ``missing`` parameter is passed
  for required fields (:issue:`1040`).
  - Extra keyword arguments passed to ``ValidationError`` in validators
  are no longer passed to the final ``ValidationError`` raised upon
  validation completion (:issue:`996`).

3.0.0rc1

+++++++++++++++++++++
  
  Features:
  
  - *Backwards-incompatible*: Rework ``ValidationError`` API.
  It now expects a single field name, and error structures are merged
  in the final ``ValidationError`` raised when validation completes.
  This allows schema-level validators to raise errors for individual
  fields (:issue:`441`). Thanks :user:`maximkulkin` for
  writing the original ``merge_errors`` implementation in :pr:`442` and thanks
  :user:`lafrech` for completing the implementation in :pr:`1026`.
  
  Bug fixes:
  
  - Fix ``TypeError`` when serializing ``None`` with ``Pluck`` (:pr:`1049`).
  Thanks :user:`toffan` for the catch and patch.

3.0.0b20

+++++++++++++++++++++
  
  Bug fixes:
  
  - Includes bug fixes from 2.16.2 and 2.16.3.

3.0.0b19

+++++++++++++++++++++
  
  Features:
  
  - Support partial loading of nested fields (:pr:`438`). Thanks
  :user:`arbor-dwatson` for the PR. *Note*: Subclasses of ``fields.Nested``
  now take an additional ``partial`` parameter in the ``_deserialize``
  method.
  
  Bug fixes:
  
  - Restore ``Schema.TYPE_MAPPING``, which was removed in 3.0.0b17 (:issue:`1012`).
  
  Other changes:
  
  - *Backwards-incompatible*: ``_serialize`` and ``_deserialize`` methods of
  all ``fields.Field`` subclasses must accept ``**kwargs`` (:pr:`1007`).

3.0.0b18

+++++++++++++++++++++
  
  Bug fixes:
  
  - Fix ``Date`` deserialization when using custom format (:issue:`1001`). Thanks
  :user:`Ondkloss` for reporting.
  
  Deprecations/Removals:
  
  - ``prefix`` parameter or ``Schema`` class is removed (:issue:`991`). The same
  can be achieved using a ``post_dump`` method.

3.0.0b17

+++++++++++++++++++++
  
  Features:
  
  - Add ``format`` option to ``Date`` field (:pr:`869`).
  - *Backwards-incompatible*: Rename ``DateTime``'s ``dateformat`` Meta option
  to ``datetimeformat``. ``dateformat`` now applies to ``Date`` (:pr:`869`).
  Thanks :user:`knagra` for implementing these changes.
  - Enforce ISO 8601 when deserializing date and time (:issue:`899`).
  Thanks :user:`dushr` for the report and the work on the PR.
  - *Backwards-incompatible*: Raise ``ValueError`` on ``Schema`` instantiation in
  case of ``attribute`` or ``data_key`` collision (:pr:`992`).
  
  Bug fixes:
  
  - Fix inconsistencies in field inference by refactoring the inference feature
  into a dedicated field (:issue:`809`). Thanks :user:`taion` for the PR.
  - When ``unknown`` is not passed to ``Nested``, default to nested ``Schema``
  ``unknown`` meta option rather than ``RAISE`` (:pr:`963`).
  Thanks :user:`vgavro` for the PR.
  - Fix loading behavior of ``fields.Pluck`` (:pr:`990`).
  - Includes bug fix from 2.16.0.

3.0.0b16

+++++++++++++++++++++
  
  Bug fixes:
  
  - Fix ``root`` attribute for nested container fields
  on inheriting schemas (:issue:`956`). Thanks :user:`bmcbu`
  for reporting.

3.0.0b15

+++++++++++++++++++++
  
  Bug fixes:
  
  - Raise ``ValidationError`` instead of ``TypeError`` when non-iterable types are
  validated with ``many=True`` (:issue:`851`).
  - ``many=True`` no longer iterates over ``str`` and ``collections.abc.Mapping`` objects and instead
  raises a ``ValidationError`` with ``{'_schema': ['Invalid input type.']}`` (:issue:`930`).
  - Return ``[]`` as ``ValidationError.valid_data`` instead of ``{}`` when
  ``many=True`` (:issue:`907`).
  
  Thanks :user:`tuukkamustonen` for implementing these changes.

3.0.0b14

+++++++++++++++++++++
  
  Features:
  
  - Add ``fields.Pluck`` for serializing a single field from a nested object
  (:issue:`800`). Thanks :user:`timc13` for the feedback and :user:`deckar01`
  for the implementation.
  - *Backwards-incompatible*: Passing a string argument as ``only`` to
  ``fields.Nested`` is no longer supported. Use ``fields.Pluck`` instead
  (:issue:`800`).
  - Raise a ``StringNotCollectionError`` if ``only`` or ``exclude`` is
  passed as a string to ``fields.Nested`` (:pr:`931`).
  - *Backwards-incompatible*: ``Float`` takes an ``allow_nan`` parameter to
  explicitly allow serializing and deserializing special values (``nan``,
  ``inf`` and ``-inf``). ``allow_nan`` defaults to ``False``.
  
  Other changes:
  
  - *Backwards-incompatible*: ``Nested`` field now defaults to ``unknown=RAISE``
  instead of ``EXCLUDE``. This harmonizes behavior with ``Schema`` that
  already defaults to ``RAISE`` (:issue:`908`). Thanks :user:`tuukkamustonen`.
  - Tested against Python 3.7.

3.0.0b13

+++++++++++++++++++++
  
  Bug fixes:
  
  - Errors reported by a schema-level validator for a field in a ``Nested`` field
  are stored under corresponding field name, not ``_schema`` key (:pr:`862`).
  - Includes bug fix from 2.15.4.
  
  Other changes:
  
  - *Backwards-incompatible*: The ``unknown`` option now defaults to ``RAISE``
  (`524 (comment) <https://github.com/marshmallow-code/marshmallow/issues/524#issuecomment-397165731>`_,
  :issue:`851`).
  - *Backwards-incompatible*: When a schema error is raised with a ``dict`` as
  payload, the ``dict`` overwrites any existing error list. Before this change,
  it would be appended to the list.
  - Raise a `StringNotCollectionError` if ``only`` or ``exclude`` is
  passed as a string (:issue:`316`). Thanks :user:`paulocheque` for
  reporting.

3.0.0b12

+++++++++++++++++++++
  
  Features:
  
  - The behavior to apply when encountering unknown fields while deserializing
  can be controlled with the ``unknown`` option (:issue:`524`,
  :issue:`747`, :issue:`127`).
  It makes it possible to either "include", "exclude", or "raise".
  Thanks :user:`tuukkamustonen` for the suggestion and thanks
  :user:`ramnes` for the PR.
  
  .. warning::
  
  The default for ``unknown`` will be changed to ``RAISE`` in the
  next release.
  
  Other changes:
  
  - *Backwards-incompatible*: Pre/Post-processors MUST return modified data.
  Returning ``None`` does not imply data were mutated (:issue:`347`). Thanks
  :user:`tdevelioglu` for reporting.
  - *Backwards-incompatible*: ``only`` and ``exclude`` are bound by
  declared and additional fields. A ``ValueError`` is raised if invalid
  fields are passed (:issue:`636`). Thanks :user:`jan-23` for reporting.
  Thanks :user:`ikilledthecat` and :user:`deckar01` for the PRs.
  - Format code using pre-commit (:pr:`855`).
  
  Deprecations/Removals:
  
  - ``ValidationError.fields`` is removed (:issue:`840`). Access field
  instances from ``Schema.fields``.

3.0.0b11

+++++++++++++++++++++
  
  Features:
  
  - Clean up code for schema hooks (:pr:`814`). Thanks :user:`taion`.
  - Minor performance improvement from simplifying ``utils.get_value`` (:pr:`811`). Thanks again :user:`taion`.
  - Add ``require_tld`` argument to ``fields.URL`` (:issue:`749`). Thanks
  :user:`DenerKup` for reporting and thanks :user:`surik00` for the PR.
  - ``fields.UUID`` deserializes ``bytes`` strings using ``UUID(bytes=b'...')`` (:pr:`625`).
  Thanks :user:`JeffBerger` for the suggestion and the PR.
  
  Bug fixes:
  
  - Fields nested within ``Dict`` correctly inherit context from their
  parent schema (:issue:`820`). Thanks :user:`RosanneZe` for reporting
  and :user:`deckar01` for the PR.
  - Includes bug fix from 2.15.3.

3.0.0b10

+++++++++++++++++++++
  
  Bug fixes:
  
  - Includes bugfixes from 2.15.2.

3.0.0b9

++++++++++++++++++++
  
  Features:
  
  - *Backwards-incompatible*: ``missing`` and ``default`` values are
  passed in deserialized form (:issue:`378`). Thanks :user:`chadrik` for
  the suggestion and thanks :user:`lafrech` for the PR.
  
  Bug fixes:
  
  - Includes the bugfix from 2.15.1.

3.0.0b8 not secure

++++++++++++++++++++
  
  Features:
  
  - *Backwards-incompatible*: Add ``data_key`` parameter to fields for
  specifying the key in the input and output data dict. This
  parameter replaces both ``load_from`` and ``dump_to`` (:issue:`717`).
  Thanks :user:`lafrech`.
  - *Backwards-incompatible*: When ``pass_original=True`` is passed to one
  of the decorators and a collection is being (de)serialized, the
  ``original_data`` argument will be a single object unless
  ``pass_many=True`` is also passed to the decorator (:issue:`315`,
  :issue:`743`). Thanks :user:`stj` for the PR.
  - *Backwards-incompatible*: Don't recursively check nested required
  fields when the ``Nested`` field's key is missing (:issue:`319`). This
  reverts :pr:`235`. Thanks :user:`chekunkov` reporting and thanks
  :user:`lafrech` for the PR.
  - *Backwards-incompatible*: Change error message collection for ``Dict`` field (:issue:`730`). Note:
  this is backwards-incompatible with previous 3.0.0bX versions.
  Thanks :user:`shabble` for the report and thanks :user:`lafrech` for the PR.

3.0.0b7 not secure

++++++++++++++++++++
  
  Features:
  
  - *Backwards-incompatible*: Schemas are always strict (:issue:`377`).
  The ``strict`` parameter is removed.
  - *Backwards-incompatible*: ``Schema().load`` and ``Schema().dump`` return ``data`` instead of a
  ``(data, errors)`` tuple (:issue:`598`).
  - *Backwards-incomaptible*: ``Schema().load(None)`` raises a
  ``ValidationError`` (:issue:`511`).
  
  See :ref:`upgrading_3_0` for a guide on updating your code.
  
  Thanks :user:`lafrech` for implementing these changes.
  Special thanks to :user:`MichalKononenko`, :user:`douglas-treadwell`, and
  :user:`maximkulkin` for the discussions on these changes.
  
  
  Other changes:
  
  - *Backwards-incompatible*: Field name is not checked when ``load_from``
  is specified (:pr:`714`). Thanks :user:`lafrech`.
  
  Support:
  
  - Add `Code of Conduct <https://marshmallow.readthedocs.io/en/dev/code_of_conduct.html>`_.

3.0.0b6 not secure

++++++++++++++++++++
  
  Bug fixes:
  
  - Fixes ``ValidationError.valid_data`` when a nested field contains errors
  (:issue:`710`). This bug was introduced in 3.0.0b3. Thanks
  :user:`lafrech`.
  
  Other changes:
  
  - *Backwards-incompatible*: ``Email`` and ``URL`` fields don't validate
  on serialization (:issue:`608`). This makes them more consistent with the other
  fields and improves serialization performance. Thanks again :user:`lafrech`.
  - ``validate.URL`` requires square brackets around IPv6 URLs (:issue:`707`). Thanks :user:`harlov`.

3.0.0b5 not secure

++++++++++++++++++++
  
  Features:
  
  - Add support for structured dictionaries by providing values and keys arguments to the
  ``Dict`` field's constructor. This mirrors the ``List``
  field's ability to validate its items (:issue:`483`). Thanks :user:`deckar01`.
  
  Other changes:
  
  - *Backwards-incompatible*: ``utils.from_iso`` is deprecated in favor of
  ``utils.from_iso_datetime`` (:issue:`694`). Thanks :user:`sklarsa`.

3.0.0b4 not secure

++++++++++++++++++++
  
  Features:
  
  - Add support for millisecond, minute, hour, and week precisions to
  ``fields.TimeDelta`` (:issue:`537`). Thanks :user:`Fedalto` for the
  suggestion and the PR.
  - Includes features from release 2.14.0.
  
  
  Support:
  
  - Copyright year in docs uses ``CHANGELOG.rst``'s modified date for
  reproducible builds (:issue:`679`). Thanks :user:`bmwiedemann`.
  - Test against Python 3.6 in tox. Thanks :user:`Fedalto`.
  - Fix typo in exception message (:issue:`659`). Thanks :user:`wonderbeyond`
  for reporting and thanks :user:`yoichi` for the PR.

3.0.0b3 not secure

++++++++++++++++++++
  
  Features:
  
  - Add ``valid_data`` attribute to ``ValidationError``.
  - Add ``strict`` parameter to ``Integer`` (:issue:`667`). Thanks
  :user:`yoichi`.
  
  Deprecations/Removals:
  
  - Deprecate ``json_module`` option in favor of ``render_module`` (:issue:`364`, :issue:`130`). Thanks :user:`justanr` for the suggestion.
  
  Bug fixes:
  
  - Includes bug fixes from releases 2.13.5 and 2.13.6.
  - *Backwards-incompatible*: ``Number`` fields don't accept booleans as valid input (:issue:`623`). Thanks :user:`tuukkamustonen` for the suggestion and thanks :user:`rowillia` for the PR.
  
  Support:
  
  - Add benchmark script. Thanks :user:`rowillia`.

3.0.0b2 not secure

++++++++++++++++++++
  
  Features:
  
  - Add ``truthy`` and ``falsy`` params to ``fields.Boolean`` (:issue:`580`). Thanks :user:`zwack` for the PR. Note: This is potentially a breaking change if your code passes the `default` parameter positionally. Pass `default` as a keyword argument instead, e.g. ``fields.Boolean(default=True)``.
  
  Other changes:
  
  - *Backwards-incompatible*: ``validate.ContainsOnly`` allows empty and duplicate values (:issue:`516`, :issue:`603`). Thanks :user:`maximkulkin` for the suggestion and thanks :user:`lafrech` for the PR.
  
  Bug fixes:
  
  - Includes bug fixes from release 2.13.4.

3.0.0b1 not secure

++++++++++++++++++++
  
  Features:
  
  - ``fields.Nested`` respects ``only='field'`` when deserializing (:issue:`307`). Thanks :user:`erlingbo` for the suggestion and the PR.
  - ``fields.Boolean`` parses ``"on"``/``"off"`` (:issue:`580`). Thanks :user:`marcellarius` for the suggestion.
  
  
  Other changes:
  
  - Includes changes from release 2.13.2.
  - *Backwards-incompatible*: ``skip_on_field_errors`` defaults to ``True`` for ``validates_schema`` (:issue:`352`).

3.0.0a1 not secure

++++++++++++++++++++
  
  Features:
  
  - ``dump_only`` and ``load_only`` for ``Function`` and ``Method`` are set based on ``serialize`` and ``deserialize`` arguments (:issue:`328`).
  
  Other changes:
  
  - *Backwards-incompatible*: ``fields.Method`` and ``fields.Function`` no longer swallow ``AttributeErrors`` (:issue:`395`). Thanks :user:`bereal` for the suggestion.
  - *Backwards-incompatible*: ``validators.Length`` is no longer a subclass of ``validators.Range`` (:issue:`458`). Thanks :user:`deckar01` for the catch and patch.
  - *Backwards-incompatible*: ``utils.get_func_args`` no longer returns bound arguments. This is consistent with the behavior of ``inspect.signature``. This change prevents a DeprecationWarning on Python 3.5 (:issue:`415`, :issue:`479`). Thanks :user:`deckar01` for the PR.
  - *Backwards-incompatible*: Change the signature of ``utils.get_value`` and ``Schema.get_attribute`` for consistency with Python builtins (e.g. ``getattr``) (:issue:`341`). Thanks :user:`stas` for reporting and thanks :user:`deckar01` for the PR.
  - *Backwards-incompatible*: Don't unconditionally call callable attributes (:issue:`430`, reverts :issue:`242`). Thanks :user:`mirko` for the suggestion.
  - Drop support for Python 2.6 and 3.3.
  
  Deprecation/Removals:
  
  - Remove ``__error_handler__``, ``__accessor__``, ``Schema.error_handler``, and ``Schema.accessor``. Override ``Schema.handle_error`` and ``Schema.get_attribute`` instead.
  - Remove ``func`` parameter of ``fields.Function``. Remove ``method_name`` parameter of ``fields.Method`` (issue:`325`). Use the ``serialize`` parameter instead.
  - Remove ``extra`` parameter from ``Schema``. Use a ``post_dump`` method to add additional data.

2.21.0

+++++++++++++++++++
  
  Bug fixes:
  
  - Don't match string-ending newlines in ``URL`` and ``Email`` fields
  (:issue:`1522`). Thanks :user:`nbanmp` for the PR.
  
  Other changes:
  
  - Drop support for Python 3.4 (:pr:`1525`).

2.20.5

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix behavior when a non-list collection is passed to the ``validate`` argument of ``fields.Email`` and ``fields.URL`` (:issue:`1400`).

2.20.4

+++++++++++++++++++
  
  Bug fixes:
  
  - Respect the ``many`` value on ``Schema`` instances passed to ``Nested`` (:issue:`1160`).
  Thanks :user:`Kamforka` for reporting.

2.20.3

+++++++++++++++++++
  
  Bug fixes:
  
  - Don't swallow ``TypeError`` exceptions raised by ``Field._bind_to_schema`` or ``Schema.on_bind_field`` (:pr:`1376`).

2.20.2

+++++++++++++++++++
  
  Bug fixes:
  
  - Prevent warning about importing from ``collections`` on Python 3.7
  (:pr:`1354`). Thanks :user:`nicktimko` for the PR.

2.20.1

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix bug that raised ``TypeError`` when invalid data type is
  passed to a nested schema with ``validates`` (:issue:`1342`).

2.20.0

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix deprecated functions' compatibility with Python 2 (:issue:`1337`).
  Thanks :user:`airstandley` for the catch and patch.
  - Fix error message consistency for invalid input types on nested fields (:issue:`1303`).
  This is a backport of the fix in :pr:`857`. Thanks :user:`cristi23` for the
  thorough bug report and the PR.
  
  Deprecation/Removal:
  
  - Python 2.6 is no longer officially supported (:issue:`1274`).

2.19.5

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix deserializing ISO8601-formatted datetimes with less than 6-digit
  miroseconds (:issue:`1251`). Thanks :user:`diego-plan9` for reporting.

2.19.4

+++++++++++++++++++
  
  Bug fixes:
  
  - Microseconds no longer gets lost when deserializing datetimes without dateutil
  installed (:issue:`1147`).

2.19.3

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix bug where nested fields in ``Meta.exclude`` would not work on
  multiple instantiations (:issue:`1212`). Thanks :user:`MHannila` for
  reporting.

2.19.2

+++++++++++++++++++
  
  Bug fixes:
  
  - Handle ``OverflowError`` when (de)serializing large integers with
  ``fields.Float`` (:pr:`1177`). Thanks :user:`brycedrennan` for the PR.

2.19.1

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix bug where ``Nested(many=True)`` would skip first element when
  serializing a generator (:issue:`1163`). Thanks :user:`khvn26` for the
  catch and patch.

2.19.0

+++++++++++++++++++
  
  Deprecation/Removal:
  
  - A ``RemovedInMarshmallow3`` warning is raised when using
  ``fields.FormattedString``. Use ``fields.Method`` or ``fields.Function``
  instead (:issue:`1141`).

2.18.1

+++++++++++++++++++
  
  Bug fixes:
  
  - A ``ChangedInMarshmallow3Warning`` is no longer raised when
  ``strict=False`` (:issue:`1108`). Thanks :user:`Aegdesil` for
  reporting.

2.18.0

+++++++++++++++++++
  
  Features:
  
  - Add warnings for functions in ``marshmallow.utils`` that are removed in
  marshmallow 3.
  
  Bug fixes:
  
  - Copying ``missing`` with ``copy.copy`` or ``copy.deepcopy`` will not
  duplicate it (:pr:`1099`).

2.17.0

+++++++++++++++++++
  
  Features:
  
  - Add ``marshmallow.__version_info__`` (:pr:`1074`).
  - Add warnings for API that is deprecated or changed to help users
  prepare for marshmallow 3 (:pr:`1075`).

2.16.3

+++++++++++++++++++
  
  Bug fixes:
  
  - Prevent memory leak when dynamically creating classes with ``type()``
  (:issue:`732`). Thanks :user:`asmodehn` for writing the tests to
  reproduce this issue.

2.16.2

+++++++++++++++++++
  
  Bug fixes:
  
  - Prevent warning about importing from ``collections`` on Python 3.7
  (:issue:`1027`). Thanks :user:`nkonin` for reporting and
  :user:`jmargeta` for the PR.

2.16.1

+++++++++++++++++++
  
  Bug fixes:
  
  - Remove spurious warning about implicit collection handling
  (:issue:`998`). Thanks :user:`lalvarezguillen` for reporting.

2.16.0

+++++++++++++++++++
  
  Bug fixes:
  
  - Allow username without password in basic auth part of the url in
  ``fields.Url`` (:pr:`982`). Thanks user:`alefnula` for the PR.
  
  Other changes:
  
  - Drop support for Python 3.3 (:pr:`987`).

2.15.6

+++++++++++++++++++
  
  Bug fixes:
  
  - Prevent ``TypeError`` when a non-collection is passed to a ``Schema`` with ``many=True``.
  Instead, raise ``ValidationError`` with ``{'_schema': ['Invalid input type.']}`` (:issue:`906`).
  - Fix ``root`` attribute for nested container fields on list
  on inheriting schemas (:issue:`956`). Thanks :user:`bmcbu`
  for reporting.
  
  These fixes were backported from 3.0.0b15 and 3.0.0b16.

2.15.5

+++++++++++++++++++
  
  Bug fixes:
  
  - Handle empty SQLAlchemy lazy lists gracefully when dumping (:issue:`948`).
  Thanks :user:`vke-code` for the catch and :user:`YuriHeupa` for the patch.

2.15.4

+++++++++++++++++++
  
  Bug fixes:
  
  - Respect ``load_from`` when reporting errors for ``validates('field_name')``
  (:issue:`748`). Thanks :user:`m-novikov` for the catch and patch.

2.15.3

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix passing ``only`` as a string to ``nested`` when the passed field
  defines ``dump_to`` (:issue:`800`, :issue:`822`). Thanks
  :user:`deckar01` for the catch and patch.

2.15.2

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix a race condition in validation when concurrent threads use the
  same ``Schema`` instance (:issue:`783`). Thanks :user:`yupeng0921` and
  :user:`lafrech` for the fix.
  - Fix serialization behavior of
  ``fields.List(fields.Integer(as_string=True))`` (:issue:`788`). Thanks
  :user:`cactus` for reporting and :user:`lafrech` for the fix.
  - Fix behavior of ``exclude`` parameter when passed from parent to
  nested schemas (:issue:`728`). Thanks :user:`timc13` for reporting and
  :user:`deckar01` for the fix.

2.15.1

+++++++++++++++++++
  
  Bug fixes:
  
  - :cve:`CVE-2018-17175`: Fix behavior when an empty list is passed as the ``only`` argument
  (:issue:`772`). Thanks :user:`deckar01` for reporting and thanks
  :user:`lafrech` for the fix.

2.15.0 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Handle ``UnicodeDecodeError`` when deserializing ``bytes`` with a
  ``String`` field (:issue:`650`). Thanks :user:`dan-blanchard` for the
  suggestion and thanks :user:`4lissonsilveira` for the PR.

2.14.0 not secure

+++++++++++++++++++
  
  Features:
  
  - Add ``require_tld`` parameter to ``validate.URL`` (:issue:`664`).
  Thanks :user:`sduthil` for the suggestion and the PR.

2.13.6 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix serialization of types that implement `__getitem__`
  (:issue:`669`). Thanks :user:`MichalKononenko`.

2.13.5 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix validation of iso8601-formatted dates (:issue:`556`). Thanks :user:`lafrech` for reporting.

2.13.4 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix symmetry of serialization and deserialization behavior when passing a dot-delimited path to the ``attribute`` parameter of fields (:issue:`450`). Thanks :user:`itajaja` for reporting.

2.13.3 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Restore backwards-compatibility of ``SchemaOpts`` constructor (:issue:`597`). Thanks :user:`Wesmania` for reporting and thanks :user:`frol` for the fix.

2.13.2 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix inheritance of ``ordered`` option when ``Schema`` subclasses define ``class Meta`` (:issue:`593`). Thanks :user:`frol`.
  
  Support:
  
  - Update contributing docs.

2.13.1 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix sorting on Schema subclasses when ``ordered=True`` (:issue:`592`). Thanks :user:`frol`.

2.13.0 not secure

+++++++++++++++++++
  
  Features:
  
  - Minor optimizations (:issue:`577`). Thanks :user:`rowillia` for the PR.

2.12.2 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Unbound fields return `None` rather returning the field itself. This fixes a corner case introduced in :issue:`572`. Thanks :user:`touilleMan` for reporting and :user:`YuriHeupa` for the fix.

2.12.1 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix behavior when a ``Nested`` field is composed within a ``List`` field (:issue:`572`). Thanks :user:`avish` for reporting and :user:`YuriHeupa` for the PR.

2.12.0 not secure

+++++++++++++++++++
  
  Features:
  
  - Allow passing nested attributes (e.g. ``'child.field'``) to the ``dump_only`` and ``load_only`` parameters of ``Schema`` (:issue:`572`). Thanks :user:`YuriHeupa` for the PR.
  - Add ``schemes`` parameter to ``fields.URL`` (:issue:`574`). Thanks :user:`mosquito` for the PR.

2.11.1 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Allow ``strict`` class Meta option to be overriden by constructor (:issue:`550`). Thanks :user:`douglas-treadwell` for reporting and thanks :user:`podhmo` for the PR.

2.11.0 not secure

+++++++++++++++++++
  
  Features:
  
  - Import ``marshmallow.fields`` in ``marshmallow/__init__.py`` to save an import when importing the ``marshmallow`` module (:issue:`557`). Thanks :user:`mindojo-victor`.
  
  Support:
  
  - Documentation: Improve example in "Validating Original Input Data" (:issue:`558`). Thanks :user:`altaurog`.
  - Test against Python 3.6.

2.10.5 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Reset user-defined kwargs passed to ``ValidationError`` on each ``Schema.load`` call (:issue:`565`). Thanks :user:`jbasko` for the catch and patch.
  
  Support:
  
  - Tests: Fix redefinition of ``test_utils.test_get_value()`` (:issue:`562`). Thanks :user:`nelfin`.

2.10.4 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - `Function` field works with callables that use Python 3 type annotations (:issue:`540`). Thanks :user:`martinstein` for reporting and thanks :user:`sabinem`, :user:`lafrech`, and :user:`maximkulkin` for the work on the PR.

2.10.3 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix behavior for serializing missing data with ``Number`` fields when ``as_string=True`` is passed (:issue:`538`). Thanks :user:`jessemyers` for reporting.

2.10.2 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Use fixed-point notation rather than engineering notation when serializing with ``Decimal`` (:issue:`534`). Thanks :user:`gdub`.
  - Fix UUID validation on serialization and deserialization of ``uuid.UUID`` objects (:issue:`532`). Thanks :user:`pauljz`.

2.10.1 not secure

+++++++++++++++++++
  
  Bug fixes:
  
  - Fix behavior when using ``validate.Equal(False)`` (:issue:`484`). Thanks :user:`pktangyue` for reporting and thanks :user:`tuukkamustonen` for the fix.
  - Fix ``strict`` behavior when errors are raised in ``pre_dump``/``post_dump`` processors (:issue:`521`). Thanks :user:`tvuotila` for the catch and patch.
  - Fix validation of nested fields on dumping (:issue:`528`). Thanks again :user:`tvuotila`.

2.10.0 not secure

+++++++++++++++++++
  
  Features:
  
  - Errors raised by pre/post-load/dump methods will be added to a schema's errors dictionary (:issue:`472`). Thanks :user:`dbertouille` for the suggestion and for the PR.

2.9.1 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - Fix serialization of ``datetime.time`` objects with microseconds (:issue:`464`). Thanks :user:`Tim-Erwin` for reporting and thanks :user:`vuonghv` for the fix.
  - Make ``validates`` consistent with field validator behavior: if validation fails, the field will not be included in the deserialized output (:issue:`391`). Thanks :user:`martinstein` for reporting and thanks :user:`vuonghv` for the fix.

2.9.0 not secure

++++++++++++++++++
  
  - ``Decimal`` field coerces input values to a string before deserializing to a `decimal.Decimal` object in order to avoid transformation of float values under 12 significant digits (:issue:`434`, :issue:`435`). Thanks :user:`davidthornton` for the PR.

2.8.0 not secure

++++++++++++++++++
  
  Features:
  
  - Allow ``only`` and ``exclude`` parameters to take nested fields, using dot-delimited syntax (e.g. ``only=['blog.author.email']``) (:issue:`402`). Thanks :user:`Tim-Erwin` and :user:`deckar01` for the discussion and implementation.
  
  Support:
  
  - Update tasks.py for compatibility with invoke>=0.13.0. Thanks :user:`deckar01`.

2.7.3 not secure

++++++++++++++++++
  
  - Make ``field.parent`` and ``field.name`` accessible to ``on_bind_field`` (:issue:`449`). Thanks :user:`immerrr`.

2.7.2 not secure

++++++++++++++++++
  
  No code changes in this release. This is a reupload in order to distribute an sdist for the last hotfix release. See :issue:`443`.
  
  Support:
  
  - Update license entry in setup.py to fix RPM distributions (:issue:`433`). Thanks :user:`rrajaravi` for reporting.

2.7.1 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - Only add Schemas to class registry if a class name is provided. This allows Schemas to be
  constructed dynamically using the ``type`` constructor without getting added to the class registry (which is useful for saving memory).

2.7.0 not secure

++++++++++++++++++
  
  Features:
  
  - Make context available to ``Nested`` field's ``on_bind_field`` method (:issue:`408`). Thanks :user:`immerrr` for the PR.
  - Pass through user ``ValidationError`` kwargs (:issue:`418`). Thanks :user:`russelldavies` for helping implement this.
  
  Other changes:
  
  - Remove unused attributes ``root``, ``parent``, and ``name`` from ``SchemaABC`` (:issue:`410`). Thanks :user:`Tim-Erwin` for the PR.

2.6.1 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - Respect ``load_from`` when reporting errors for nested required fields (:issue:`414`). Thanks :user:`yumike`.

2.6.0 not secure

++++++++++++++++++
  
  Features:
  
  - Add ``partial`` argument to ``Schema.validate`` (:issue:`379`). Thanks :user:`tdevelioglu` for the PR.
  - Add ``equal`` argument to ``validate.Length``. Thanks :user:`daniloakamine`.
  - Collect all validation errors for each item deserialized by a ``List`` field (:issue:`345`). Thanks :user:`maximkulkin` for the report and the PR.

2.5.0 not secure

++++++++++++++++++
  
  Features:
  
  - Allow a tuple of field names to be passed as the ``partial`` argument to ``Schema.load`` (:issue:`369`). Thanks :user:`tdevelioglu` for the PR.
  - Add ``schemes`` argument to ``validate.URL`` (:issue:`356`).

2.4.2 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - Prevent duplicate error messages when validating nested collections (:issue:`360`). Thanks :user:`alexmorken` for the catch and patch.

2.4.1 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - Serializing an iterator will not drop the first item (:issue:`343`, :issue:`353`). Thanks :user:`jmcarp` for the patch. Thanks :user:`edgarallang` and :user:`jmcarp` for reporting.

2.4.0 not secure

++++++++++++++++++
  
  Features:
  
  - Add ``skip_on_field_errors`` parameter to ``validates_schema`` (:issue:`323`). Thanks :user:`jjvattamattom` for the suggestion and :user:`d-sutherland` for the PR.
  
  Bug fixes:
  
  - Fix ``FormattedString`` serialization (:issue:`348`). Thanks :user:`acaird` for reporting.
  - Fix ``validates`` behavior when used when ``attribute`` is specified and ``strict=True`` (:issue:`350`). Thanks :user:`density` for reporting.

2.3.0 not secure

++++++++++++++++++
  
  Features:
  
  - Add ``dump_to`` parameter to fields (:issue:`310`). Thanks :user:`ShayanArmanPercolate` for the suggestion. Thanks :user:`franciscod` and :user:`ewang` for the PRs.
  - The ``deserialize`` function passed to ``fields.Function`` can optionally receive a ``context`` argument (:issue:`324`). Thanks :user:`DamianHeard`.
  - The ``serialize`` function passed to ``fields.Function`` is optional (:issue:`325`). Thanks again :user:`DamianHeard`.
  - The ``serialize`` function passed to ``fields.Method`` is optional (:issue:`329`). Thanks :user:`justanr`.
  
  Deprecation/Removal:
  
  - The ``func`` argument of ``fields.Function`` has been renamed to ``serialize``.
  - The ``method_name`` argument of ``fields.Method`` has been renamed to ``serialize``.
  
  ``func`` and ``method_name`` are still present for backwards-compatibility, but they will both be removed in marshmallow 3.0.

2.2.1 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - Skip field validators for fields that aren't included in ``only`` (:issue:`320`). Thanks :user:`carlos-alberto` for reporting and :user:`eprikazc` for the PR.

2.2.0 not secure

++++++++++++++++++
  
  Features:
  
  - Add support for partial deserialization with the ``partial`` argument to ``Schema`` and ``Schema.load`` (:issue:`290`). Thanks :user:`taion`.
  
  Deprecation/Removals:
  
  - ``Query`` and ``QuerySelect`` fields are removed.
  - Passing of strings to ``required`` and ``allow_none`` is removed. Pass the ``error_messages`` argument instead.
  
  Support:
  
  - Add example of Schema inheritance in docs (:issue:`225`). Thanks :user:`martinstein` for the suggestion and :user:`juanrossi` for the PR.
  - Add "Customizing Error Messages" section to custom fields docs.

2.1.3 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - Fix serialization of collections for which ``iter`` will modify position, e.g. Pymongo cursors (:issue:`303`). Thanks :user:`Mise` for the catch and patch.

2.1.2 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - Fix passing data to schema validator when using ``validates_schema(many=True)`` (:issue:`297`). Thanks :user:`d-sutherland` for reporting.
  - Fix usage of ``validates`` with a nested field when ``many=True`` (:issue:`298`). Thanks :user:`nelfin` for the catch and patch.

2.1.1 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - ``Constant`` field deserializes to its value regardless of whether its field name is present in input data (:issue:`291`). Thanks :user:`fayazkhan` for reporting.

2.1.0 not secure

++++++++++++++++++
  
  Features:
  
  - Add ``Dict`` field for arbitrary mapping data (:issue:`251`). Thanks :user:`dwieeb` for adding this and :user:`Dowwie` for the suggestion.
  - Add ``Field.root`` property, which references the field's Schema.
  
  Deprecation/Removals:
  
  - The ``extra`` param of ``Schema`` is deprecated. Add extra data in a ``post_load`` method instead.
  - ``UnmarshallingError`` and ``MarshallingError`` are removed.
  
  Bug fixes:
  
  - Fix storing multiple schema-level validation errors (:issue:`287`). Thanks :user:`evgeny-sureev` for the patch.
  - If ``missing=None`` on a field, ``allow_none`` will be set to ``True``.
  
  Other changes:
  
  - A ``List's`` inner field will have the list field set as its parent. Use ``root`` to access the ``Schema``.

2.0.0 not secure

++++++++++++++++++
  
  Features:
  
  - Make error messages configurable at the class level and instance level (``Field.default_error_messages`` attribute and ``error_messages`` parameter, respectively).
  
  Deprecation/Removals:
  
  - Remove ``make_object``. Use a ``post_load`` method instead (:issue:`277`).
  - Remove the ``error`` parameter and attribute of ``Field``.
  - Passing string arguments to ``required`` and ``allow_none`` is deprecated. Pass the ``error_messages`` argument instead. **This API will be removed in version 2.2**.
  - Remove ``Arbitrary``, ``Fixed``, and ``Price`` fields (:issue:`86`). Use ``Decimal`` instead.
  - Remove ``Select`` / ``Enum`` fields (:issue:`135`). Use the ``OneOf`` validator instead.
  
  Bug fixes:
  
  - Fix error format for ``Nested`` fields when ``many=True``. Thanks :user:`alexmorken`.
  - ``pre_dump`` methods are invoked before implicit field creation. Thanks :user:`makmanalp` for reporting.
  - Return correct "required" error message for ``Nested`` field.
  - The ``only`` argument passed to a ``Schema`` is bounded by the ``fields`` option (:issue:`183`). Thanks :user:`lustdante` for the suggestion.

2.0.0rc2 not secure

+++++++++++++++++++++
  
  Deprecation/Removals:
  
  - ``make_object`` is deprecated. Use a ``post_load`` method instead (:issue:`277`). **This method will be removed in the final 2.0 release**.
  - ``Schema.accessor`` and ``Schema.error_handler`` decorators are deprecated. Define the ``accessor`` and ``error_handler`` class Meta options instead.
  
  Bug fixes:
  
  - Allow non-field names to be passed to ``ValidationError`` (:issue:`273`). Thanks :user:`evgeny-sureev` for the catch and patch.

2.0.0rc1 not secure

+++++++++++++++++++++
  
  Features:
  
  - *Backwards-incompatible*: ``fields.Field._deserialize`` now takes ``attr`` and ``data`` as arguments (:issue:`172`). Thanks :user:`alexmic` and :user:`kevinastone` for the suggestion.
  - Allow a ``Field's`` ``attribute`` to be modified during deserialization (:issue:`266`). Thanks :user:`floqqi`.
  - Allow partially-valid data to be returned for ``Nested`` fields (:issue:`269`). Thanks :user:`jomag` for the suggestion.
  - Add ``Schema.on_bind_field`` hook which allows a ``Schema`` to modify its fields when they are bound.
  - Stricter validation of string, boolean, and number fields (:issue:`231`). Thanks :user:`touilleMan` for the suggestion.
  - Improve consistency of error messages.
  
  Deprecation/Removals:
  
  - ``Schema.validator``, ``Schema.preprocessor``, and ``Schema.data_handler`` are removed. Use ``validates_schema``, ``pre_load``, and ``post_dump`` instead.
  - ``QuerySelect``  and ``QuerySelectList`` are deprecated (:issue:`227`). **These fields will be removed in version 2.1.**
  - ``utils.get_callable_name`` is removed.
  
  Bug fixes:
  
  - If a date format string is passed to a ``DateTime`` field, it is always used for deserialization (:issue:`248`). Thanks :user:`bartaelterman` and :user:`praveen-p`.
  
  Support:
  
  - Documentation: Add "Using Context" section to "Extending Schemas" page (:issue:`224`).
  - Include tests and docs in release tarballs (:issue:`201`).
  - Test against Python 3.5.

2.0.0b5 not secure

++++++++++++++++++++
  
  Features:
  
  - If a field corresponds to a callable attribute, it will be called upon serialization. Thanks :user:`alexmorken`.
  - Add ``load_only`` and ``dump_only`` ``class Meta`` options. Thanks :user:`kelvinhammond`.
  - If a ``Nested`` field is required, recursively validate any required fields in the nested schema (:issue:`235`). Thanks :user:`max-orhai`.
  - Improve error message if a list of dicts is not passed to a ``Nested`` field for which ``many=True``. Thanks again :user:`max-orhai`.
  
  Bug fixes:
  
  - ``make_object`` is only called after all validators and postprocessors have finished (:issue:`253`). Thanks :user:`sunsongxp` for reporting.
  - If an invalid type is passed to ``Schema`` and ``strict=False``, store a ``_schema`` error in the errors dict rather than raise an exception (:issue:`261`). Thanks :user:`density` for reporting.
  
  Other changes:
  
  - ``make_object`` is only called when input data are completely valid (:issue:`243`). Thanks :user:`kissgyorgy` for reporting.
  - Change default error messages for ``URL`` and ``Email`` validators so that they don't include user input (:issue:`255`).
  - ``Email`` validator permits email addresses with non-ASCII characters, as per RFC 6530 (:issue:`221`). Thanks :user:`lextoumbourou` for reporting and :user:`mwstobo` for sending the patch.

2.0.0b4 not secure

++++++++++++++++++++
  
  Features:
  
  - ``List`` field respects the ``attribute`` argument of the inner field. Thanks :user:`jmcarp`.
  - The ``container`` field ``List`` field has access to its parent ``Schema`` via its ``parent`` attribute. Thanks again :user:`jmcarp`.
  
  Deprecation/Removals:
  
  - Legacy validator functions have been removed (:issue:`73`). Use the class-based validators in ``marshmallow.validate`` instead.
  
  Bug fixes:
  
  - ``fields.Nested`` correctly serializes nested ``sets`` (:issue:`233`). Thanks :user:`traut`.

2.0.0b3 not secure

+++++++++++++++++++++
  
  Features:
  
  - Add ``marshmallow.validates_schema`` decorator for defining schema-level validators (:issue:`116`).
  - Add ``marshmallow.validates`` decorator for defining field validators as Schema methods (:issue:`116`). Thanks :user:`philtay`.
  - Performance improvements.
  - Defining ``__marshallable__`` on complex objects is no longer necessary.
  - Add ``fields.Constant``. Thanks :user:`kevinastone`.
  
  Deprecation/Removals:
  
  - Remove ``skip_missing`` class Meta option. By default, missing inputs are excluded from serialized output (:issue:`211`).
  - Remove optional ``context`` parameter that gets passed to methods for ``Method`` fields.
  - ``Schema.validator`` is deprecated. Use ``marshmallow.validates_schema`` instead.
  - ``utils.get_func_name`` is removed. Use ``utils.get_callable_name`` instead.
  
  Bug fixes:
  
  - Fix serializing values from keyed tuple types (regression of :issue:`28`). Thanks :user:`makmanalp` for reporting.
  
  Other changes:
  
  - Remove unnecessary call to ``utils.get_value`` for ``Function`` and ``Method`` fields (:issue:`208`). Thanks :user:`jmcarp`.
  - Serializing a collection without passing ``many=True`` will not result in an error. Be very careful to pass the ``many`` argument when necessary.
  
  Support:
  
  - Documentation: Update Flask and Peewee examples. Update Quickstart.

2.0.0b2 not secure

++++++++++++++++++++
  
  Features:
  
  - Add useful ``__repr__`` methods to validators (:issue:`204`). Thanks :user:`philtay`.
  - *Backwards-incompatible*: By default, ``NaN``, ``Infinity``, and ``-Infinity`` are invalid values for ``fields.Decimal``. Pass ``allow_nan=True`` to allow these values. Thanks :user:`philtay`.

2.0.0b1 not secure

++++++++++++++++++++
  
  Features:
  
  - Errored fields will not appear in (de)serialized output dictionaries (:issue:`153`, :issue:`202`).
  - Instantiate ``OPTIONS_CLASS`` in ``SchemaMeta``. This makes ``Schema.opts`` available in metaclass methods. It also causes validation to occur earlier (upon ``Schema`` class declaration rather than instantiation).
  - Add ``SchemaMeta.get_declared_fields`` class method to support adding additional declared fields.
  
  Deprecation/Removals:
  
  - Remove ``allow_null`` parameter of ``fields.Nested`` (:issue:`203`).

2.0.0a1 not secure

++++++++++++++++++++
  
  Features:
  
  - *Backwards-incompatible*: When ``many=True``, the errors dictionary returned by ``dump`` and ``load`` will be keyed on the indices of invalid items in the (de)serialized collection (:issue:`75`). Add ``index_errors=False`` on a Schema's ``class Meta`` options to disable this behavior.
  - *Backwards-incompatible*: By default, fields will raise a ValidationError if the input is ``None``. The ``allow_none`` parameter can override this behavior.
  - *Backwards-incompatible*: A ``Field's`` ``default`` parameter is only used if explicitly set and the field's value is missing in the input to `Schema.dump`. If not set, the key will not be present in the serialized output for missing values . This is the behavior for *all* fields. ``fields.Str`` no longer defaults to ``''``, ``fields.Int`` no longer defaults to ``0``, etc. (:issue:`199`). Thanks :user:`jmcarp` for the feedback.
  - In ``strict`` mode, a ``ValidationError`` is raised. Error messages are accessed via the ``ValidationError's`` ``messages`` attribute (:issue:`128`).
  - Add ``allow_none`` parameter to ``fields.Field``. If ``False`` (the default), validation fails when the field's value is ``None`` (:issue:`76`, :issue:`111`). If ``allow_none`` is ``True``, ``None`` is considered valid and will deserialize to ``None``.
  - Schema-level validators can store error messages for multiple fields (:issue:`118`). Thanks :user:`ksesong` for the suggestion.
  - Add ``pre_load``, ``post_load``, ``pre_dump``, and ``post_dump`` Schema method decorators for defining pre- and post- processing routines (:issue:`153`, :issue:`179`). Thanks :user:`davidism`, :user:`taion`, and :user:`jmcarp` for the suggestions and feedback. Thanks :user:`taion` for the implementation.
  - Error message for ``required`` validation is configurable. (:issue:`78`). Thanks :user:`svenstaro` for the suggestion. Thanks :user:`0xDCA` for the implementation.
  - Add ``load_from`` parameter to fields (:issue:`125`). Thanks :user:`hakjoon`.
  - Add ``load_only`` and ``dump_only`` parameters to fields (:issue:`61`, :issue:`87`). Thanks :user:`philtay`.
  - Add `missing` parameter to fields (:issue:`115`). Thanks :user:`philtay`.
  - Schema validators can take an optional ``raw_data`` argument which contains raw input data, incl. data not specified in the schema (:issue:`127`). Thanks :user:`ryanlowe0`.
  - Add ``validate.OneOf`` (:issue:`135`) and ``validate.ContainsOnly`` (:issue:`149`) validators. Thanks :user:`philtay`.
  - Error messages for validators can be interpolated with `{input}` and other values (depending on the validator).
  - ``fields.TimeDelta`` always serializes to an integer value in order to avoid rounding errors (:issue:`105`). Thanks :user:`philtay`.
  - Add ``include`` class Meta option to support field names which are Python keywords (:issue:`139`). Thanks :user:`nickretallack` for the suggestion.
  - ``exclude`` parameter is respected when used together with ``only`` parameter (:issue:`165`). Thanks :user:`lustdante` for the catch and patch.
  - ``fields.List`` works as expected with generators and sets (:issue:`185`). Thanks :user:`sergey-aganezov-jr`.
  
  Deprecation/Removals:
  
  - ``MarshallingError`` and ``UnmarshallingError`` error are deprecated in favor of a single ``ValidationError`` (:issue:`160`).
  - ``context`` argument passed to Method fields is deprecated. Use ``self.context`` instead (:issue:`184`).
  - Remove ``ForcedError``.
  - Remove support for generator functions that yield validators (:issue:`74`). Plain generators of validators are still supported.
  - The ``Select/Enum`` field is deprecated in favor of using ``validate.OneOf`` validator (:issue:`135`).
  - Remove legacy, pre-1.0 API (``Schema.data`` and ``Schema.errors`` properties) (:issue:`73`).
  - Remove ``null`` value.
  
  Other changes:
  
  - ``Marshaller``, ``Unmarshaller`` were moved to ``marshmallow.marshalling``. These should be considered private API (:issue:`129`).
  - Make ``allow_null=True`` the default for ``Nested`` fields. This will make ``None`` serialize to ``None`` rather than a dictionary with empty values (:issue:`132`). Thanks :user:`nickrellack` for the suggestion.

1.2.6 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - Fix validation error message for ``fields.Decimal``.
  - Allow error message for ``fields.Boolean`` to be customized with the ``error`` parameter (like other fields).

1.2.5 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - Fix validation of invalid types passed to a ``Nested`` field when ``many=True`` (:issue:`188`). Thanks :user:`juanrossi` for reporting.
  
  Support:
  
  - Fix pep8 dev dependency for flake8. Thanks :user:`taion`.

1.2.4 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - Fix behavior of ``as_string`` on ``fields.Integer`` (:issue:`173`). Thanks :user:`taion` for the catch and patch.
  
  Other changes:
  
  - Remove dead code from ``fields.Field``. Thanks :user:`taion`.
  
  Support:
  
  - Correction to ``_postprocess`` method in docs. Thanks again :user:`taion`.

1.2.3 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - Fix inheritance of ``ordered`` class Meta option (:issue:`162`). Thanks :user:`stephenfin` for reporting.

1.2.2 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - Fix behavior of ``skip_missing`` and ``accessor`` options when ``many=True`` (:issue:`137`). Thanks :user:`3rdcycle`.
  - Fix bug that could cause an ``AttributeError`` when nesting schemas with schema-level validators (:issue:`144`). Thanks :user:`vovanbo` for reporting.

1.2.1 not secure

++++++++++++++++++
  
  Bug fixes:
  
  - A ``Schema's`` ``error_handler``--if defined--will execute if ``Schema.validate`` returns validation errors (:issue:`121`).
  - Deserializing `None` returns `None` rather than raising an ``AttributeError`` (:issue:`123`). Thanks :user:`RealSalmon` for the catch and patch.

1.2.0 not secure

++++++++++++++++++
  
  Features:
  
  - Add ``QuerySelect`` and ``QuerySelectList`` fields (:issue:`84`).
  - Convert validators in ``marshmallow.validate`` into class-based callables to make them easier to use when declaring fields (:issue:`85`).
  - Add ``Decimal`` field which is safe to use when dealing with precise numbers (:issue:`86`).
  
  Thanks :user:`philtay` for these contributions.
  
  Bug fixes:
  
  - ``Date`` fields correctly deserializes to a ``datetime.date`` object when ``python-dateutil`` is not installed (:issue:`79`). Thanks :user:`malexer` for the catch and patch.
  - Fix bug that raised an ``AttributeError`` when using a class-based validator.
  - Fix ``as_string`` behavior of Number fields when serializing to default value.
  - Deserializing ``None`` or the empty string with either a ``DateTime``, ``Date``, ``Time`` or ``TimeDelta`` results in the correct unmarshalling errors (:issue:`96`). Thanks :user:`svenstaro` for reporting and helping with this.
  - Fix error handling when deserializing invalid UUIDs (:issue:`106`). Thanks :user:`vesauimonen` for the catch and patch.
  - ``Schema.loads`` correctly defaults to use the value of ``self.many`` rather than defaulting to ``False`` (:issue:`108`). Thanks :user:`davidism` for the catch and patch.
  - Validators, data handlers, and preprocessors are no longer shared between schema subclasses (:issue:`88`). Thanks :user:`amikholap` for reporting.
  - Fix error handling when passing a ``dict`` or ``list`` to a ``ValidationError`` (:issue:`110`). Thanks :user:`ksesong` for reporting.
  
  Deprecation:
  
  - The validator functions in the ``validate`` module are deprecated in favor of the class-based validators (:issue:`85`).
  - The ``Arbitrary``, ``Price``, and ``Fixed`` fields are deprecated in favor of the ``Decimal`` field (:issue:`86`).
  
  Support:
  
  - Update docs theme.
  - Update contributing docs (:issue:`77`).
  - Fix namespacing example in "Extending Schema" docs. Thanks :user:`Ch00k`.
  - Exclude virtualenv directories from syntax checking (:issue:`99`). Thanks :user:`svenstaro`.

1.1.0 not secure

++++++++++++++++++
  
  Features:
  
  - Add ``Schema.validate`` method which validates input data against a schema. Similar to ``Schema.load``, but does not call ``make_object`` and only returns the errors dictionary.
  - Add several validation functions to the ``validate`` module. Thanks :user:`philtay`.
  - Store field name and instance on exceptions raised in ``strict`` mode.
  
  Bug fixes:
  
  - Fix serializing dictionaries when field names are methods of ``dict`` (e.g. ``"items"``). Thanks :user:`rozenm` for reporting.
  - If a Nested field is passed ``many=True``, ``None`` serializes to an empty list. Thanks :user:`nickretallack` for reporting.
  - Fix behavior of ``many`` argument passed to ``dump`` and ``load``. Thanks :user:`svenstaro` for reporting and helping with this.
  - Fix ``skip_missing`` behavior for ``String`` and ``List`` fields. Thanks :user:`malexer` for reporting.
  - Fix compatibility with python-dateutil 2.3.
  - More consistent error messages across ``DateTime``, ``TimeDelta``, ``Date``, and ``Time`` fields.
  
  Support:
  
  - Update Flask and Peewee examples.

1.0.1 not secure

++++++++++++++++++
  
  Hotfix release.
  
  - Ensure that errors dictionary is correctly cleared on each call to ``Schema.dump`` and ``Schema.load``.

1.0.0 not secure

++++++++++++++++++
  
  Adds new features, speed improvements, better error handling, and updated documentation.
  
  - Add ``skip_missing`` ``class Meta`` option.
  - A field's ``default`` may be a callable.
  - Allow accessor function to be configured via the ``Schema.accessor`` decorator or the ``__accessor__`` class member.
  - ``URL`` and ``Email`` fields are validated upon serialization.
  - ``dump`` and ``load`` can receive the ``many`` argument.
  - Move a number of utility functions from fields.py to utils.py.
  - More useful ``repr`` for ``Field`` classes.
  - If a field's default is ``fields.missing`` and its serialized value is ``None``, it will not be included in the final serialized result.
  - Schema.dumps no longer coerces its result to a binary string on Python 3.
  - *Backwards-incompatible*: Schema output is no longer an ``OrderedDict`` by default. If you want ordered field output, you must explicitly set the ``ordered`` option to ``True``.
  - *Backwards-incompatible*: ``error`` parameter of the ``Field`` constructor is deprecated. Raise a ``ValidationError`` instead.
  - Expanded test coverage.
  - Updated docs.

1.0.0a

++++++++++++++++++++
  
  Major reworking and simplification of the public API, centered around support for deserialization, improved validation, and a less stateful ``Schema`` class.
  
  * Rename ``Serializer`` to ``Schema``.
  * Support for deserialization.
  * Use the ``Schema.dump`` and ``Schema.load`` methods for serializing and deserializing, respectively.
  * *Backwards-incompatible*: Remove ``Serializer.json`` and ``Serializer.to_json``. Use ``Schema.dumps`` instead.
  * Reworked fields interface.
  * *Backwards-incompatible*: ``Field`` classes implement ``_serialize`` and ``_deserialize`` methods. ``serialize`` and ``deserialize`` comprise the public API for a ``Field``. ``Field.format`` and ``Field.output`` have been removed.
  * Add ``exceptions.ForcedError`` which allows errors to be raised during serialization (instead of storing errors in the ``errors`` dict).
  * *Backwards-incompatible*: ``DateTime`` field serializes to ISO8601 format by default (instead of RFC822).
  * *Backwards-incompatible*: Remove ``Serializer.factory`` method. It is no longer necessary with the ``dump`` method.
  * *Backwards-incompatible*: Allow nesting a serializer within itself recursively. Use ``exclude`` or ``only`` to prevent infinite recursion.
  * *Backwards-incompatible*: Multiple errors can be stored for a single field. The errors dictionary returned by ``load`` and ``dump`` have lists of error messages keyed by field name.
  * Remove ``validated`` decorator. Validation occurs within ``Field`` methods.
  * ``Function`` field raises a ``ValueError`` if an uncallable object is passed to its constructor.
  * ``Nested`` fields inherit context from their parent.
  * Add ``Schema.preprocessor`` and ``Schema.validator`` decorators for registering preprocessing and schema-level validation functions respectively.
  * Custom error messages can be specified by raising a ``ValidationError`` within a validation function.
  * Extra keyword arguments passed to a Field are stored as metadata.
  * Fix ordering of field output.
  * Fix behavior of the ``required`` parameter on ``Nested`` fields.
  * Fix serializing keyed tuple types (e.g. ``namedtuple``) with ``class Meta`` options.
  * Fix default value for ``Fixed`` and ``Price`` fields.
  * Fix serialization of binary strings.
  * ``Schemas`` can inherit fields from non-``Schema`` base classes (e.g. mixins). Also, fields are inherited according to the MRO (rather than recursing over base classes). Thanks :user:`jmcarp`.
  * Add ``Str``, ``Bool``, and ``Int`` field class aliases.

0.7.0 not secure

++++++++++++++++++
  
  * Add ``Serializer.error_handler`` decorator that registers a custom error handler.
  * Add ``Serializer.data_handler`` decorator that registers data post-processing callbacks.
  * *Backwards-incompatible*: ``process_data`` method is deprecated. Use the ``data_handler`` decorator instead.
  * Fix bug that raised error when passing ``extra`` data together with ``many=True``. Thanks :user:`buttsicles` for reporting.
  * If ``required=True`` validation is violated for a given ``Field``, it will raise an error message that is different from the message specified by the ``error`` argument. Thanks :user:`asteinlein`.
  * More generic error message raised when required field is missing.
  * ``validated`` decorator should only wrap a ``Field`` class's ``output`` method.

0.6.0 not secure

++++++++++++++++++
  
  * Fix bug in serializing keyed tuple types, e.g. ``namedtuple`` and ``KeyedTuple``.
  * Nested field can load a serializer by its class name as a string. This makes it easier to implement 2-way nesting.
  * Make ``Serializer.data`` override-able.

0.5.5 not secure

++++++++++++++++++
  
  * Add ``Serializer.factory`` for creating a factory function that returns a Serializer instance.
  * ``MarshallingError`` stores its underlying exception as an instance variable. This is useful for inspecting errors.
  * ``fields.Select`` is aliased to ``fields.Enum``.
  * Add ``fields.__all__`` and ``marshmallow.__all__`` so that the modules can be more easily extended.
  * Expose ``Serializer.OPTIONS_CLASS`` as a class variable so that options defaults can be overridden.
  * Add ``Serializer.process_data`` hook that allows subclasses to manipulate the final output data.

0.5.4 not secure

++++++++++++++++++
  
  * Add ``json_module`` class Meta option.
  * Add ``required`` option to fields . Thanks :user:`DeaconDesperado`.
  * Tested on Python 3.4 and PyPy.

0.5.3 not secure

++++++++++++++++++
  
  * Fix ``Integer`` field default. It is now ``0`` instead of ``0.0``. Thanks :user:`kalasjocke`.
  * Add ``context`` param to ``Serializer``. Allows accessing arbitrary objects in ``Function`` and ``Method`` fields.
  * ``Function`` and ``Method`` fields raise ``MarshallingError`` if their argument is uncallable.

0.5.2 not secure

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

0.5.1 not secure

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

0.5.0 not secure

++++++++++++++++++
  
  * Can customize validation error messages by passing the ``error`` parameter to a field.
  * *Backwards-incompatible*: Rename ``fields.NumberField`` -> ``fields.Number``.
  * Add ``fields.Select``. Thanks :user:`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 not secure

++++++++++++++++++
  
  * 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 not secure

++++++++++++++++++
  
  * Add ``additional`` `class Meta` option.
  * Add ``dateformat`` `class Meta` option.
  * Support for serializing UUID, date, time, and timedelta objects.
  * Remove ``Serializer.to_data`` method. Just use ``Serialize.data`` property.
  * String field defaults to empty string instead of ``None``.
  * *Backwards-incompatible*: ``isoformat`` and ``rfcformat`` functions moved to utils.py.
  * *Backwards-incompatible*: Validation functions moved to validate.py.
  * *Backwards-incompatible*: Remove types.py.
  * 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 not secure

++++++++++++++++++
  
  * 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 not secure

++++++++++++++++++
  
  * 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 not secure

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

0.2.0 not secure

++++++++++++++++++
  
  * 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 not secure

++++++++++++++++++
  
  * First release.

Links

Releases