Marshmallow

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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.

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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``.

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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.

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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.

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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.

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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.