3.0.1 (2018-06-06)

Bug fixes:

  • Respect Parser.DEFAULT_VALIDATION_STATUS when a status_code is not explicitly passed to ValidationError (#180). Thanks @foresmac for finding this.


  • Add “Returning HTTP 400 Responses” section to docs (#180).

3.0.0 (2018-05-06)


  • Backwards-incompatible: Custom error handlers receive the request object as the second argument. Update any functions decorated with Parser.error_handler to take a req argument, like so:
# 2.x
def handle_error(error):
    raise CustomError(error.messages)

# 3.x
def handle_error(error, req):
    raise CustomError(error.messages)
  • Backwards-incompatible: Remove unused instance and kwargs arguments of argmap2schema.
  • Backwards-incompatible: Remove Parser.load method (Parser now calls Schema.load directly).

These changes shouldn’t affect most users. However, they might break custom parsers calling these methods. (#222)

  • Drop support for aiohttp<3.0.0.

2.1.0 (2018-04-01)


  • Respect data_key field argument (in marshmallow 3). Thanks @lafrech.

2.0.0 (2018-02-08)


  • Drop support for aiohttp<2.0.0.
  • Remove use of deprecated Request.has_body attribute in aiohttpparser (#186). Thanks @ariddell for reporting.

1.10.0 (2018-02-08)


  • Add support for marshmallow>=3.0.0b7 (#188). Thanks @lafrech.


  • Support for aiohttp<2.0.0 is deprecated and will be removed in webargs 2.0.0.

1.9.0 (2018-02-03)



  • Fix examples in examples/ directory.

1.8.1 (2017-07-17)

Bug fixes:

  • Fix behavior of AIOHTTPParser.use_args when as_kwargs=True is passed with a Schema (#179). Thanks @Itayazolay.

1.8.0 (2017-07-16)


  • AIOHTTPParser supports class-based views, i.e. aiohttp.web.View (#177). Thanks @daniel98321.

1.7.0 (2017-06-03)


  • AIOHTTPParser.use_args and AIOHTTPParser.use_kwargs work with async def coroutines (#170). Thanks @zaro.

1.6.3 (2017-05-18)


  • Fix Flask error handling docs in “Framework support” section (#168). Thanks @nebularazer.

1.6.2 (2017-05-16)

Bug fixes:

  • Fix parsing multiple arguments in AIOHTTParser (#165). Thanks @ariddell for reporting and thanks @zaro for reporting.

1.6.1 (2017-04-30)

Bug fixes:

  • Fix form parsing in aiohttp>=2.0.0. Thanks @DmitriyS for the PR.

1.6.0 (2017-03-14)

Bug fixes:

  • Fix compatibility with marshmallow 3.x.

Other changes:

  • Drop support for Python 2.6 and 3.3.
  • Support marshmallow>=2.7.0.

1.5.3 (2017-02-04)

Bug fixes:

  • Port fix from release 1.5.2 to AsyncParser. This fixes #146 for AIOHTTPParser.
  • Handle invalid types passed to DelimitedList (#149). Thanks @psconnect-dev for reporting.

1.5.2 (2017-01-08)

Bug fixes:

  • Don’t add marshmallow.missing to original_data when using marshmallow.validates_schema(pass_original=True) (#146). Thanks @lafrech for reporting and for the fix.

Other changes:

  • Test against Python 3.6.

1.5.1 (2016-11-27)

Bug fixes:

  • Fix handling missing nested args when many=True (#120, #145). Thanks @chavz and @Bangertm for reporting.
  • Fix behavior of load_from in AIOHTTPParser.

1.5.0 (2016-11-22)


  • The use_args and use_kwargs decorators add a reference to the undecorated function via the __wrapped__ attribute. This is useful for unit-testing purposes (#144). Thanks @EFF for the PR.

Bug fixes:

  • If load_from is specified on a field, first check the field name before checking load_from (#118). Thanks @jasonab for reporting.

1.4.0 (2016-09-29)

Bug fixes:

  • Prevent error when rendering validation errors to JSON in Flask (e.g. when using Flask-RESTful) (#122). Thanks @frol for the catch and patch. NOTE: Though this is a bugfix, this is a potentially breaking change for code that needs to access the original ValidationError object.
# Before
def handle_validation_error(err):
    return jsonify({'errors': err.messages}), 422

# After
def handle_validation_error(err):
    # The marshmallow.ValidationError is available on err.exc
    return jsonify({'errors': err.exc.messages}), 422

1.3.4 (2016-06-11)

Bug fixes:

  • Fix bug in parsing form in Falcon>=1.0.

1.3.3 (2016-05-29)

Bug fixes:

  • Fix behavior for nullable List fields (#107). Thanks @shaicantor for reporting.

1.3.2 (2016-04-14)

Bug fixes:

  • Fix passing a schema factory to use_kwargs (#103). Thanks @ksesong for reporting.

1.3.1 (2016-04-13)

Bug fixes:

  • Fix memory leak when calling parser.parse with a dict in a view (#101). Thanks @frankslaughter for reporting.
  • aiohttpparser: Fix bug in handling bulk-type arguments.


  • Massive refactor of tests (#98).
  • Docs: Fix incorrect use_args example in Tornado section (#100). Thanks @frankslaughter for reporting.
  • Docs: Add “Mixing Locations” section (#90). Thanks @tuukkamustonen.

1.3.0 (2016-04-05)


  • Add bulk-type arguments support for JSON parsing by passing many=True to a Schema (#81). Thanks @frol.

Bug fixes:

  • Fix JSON parsing in Flask<=0.9.0. Thanks @brettdh for the PR.
  • Fix behavior of status_code argument to ValidationError (#85). This requires marshmallow>=2.7.0. Thanks @ParthGandhi for reporting.


  • Docs: Add “Custom Fields” section with example of using a Function field (#94). Thanks @brettdh for the suggestion.

1.2.0 (2016-01-04)


  • Add view_args request location to FlaskParser (#82). Thanks @oreza for the suggestion.

Bug fixes:

  • Use the value of load_from as the key for error messages when it is provided (#83). Thanks @immerrr for the catch and patch.

1.1.1 (2015-11-14)

Bug fixes:

  • aiohttpparser: Fix bug that raised a JSONDecodeError raised when parsing non-JSON requests using default locations (#80). Thanks @leonidumanskiy for reporting.
  • Fix parsing JSON requests that have a vendor media type, e.g. application/vnd.api+json.

1.1.0 (2015-11-08)


  • Parser.parse, Parser.use_args and Parser.use_kwargs can take a Schema factory as the first argument (#73). Thanks @DamianHeard for the suggestion and the PR.


  • Docs: Add “Custom Parsers” section with example of parsing nested querystring arguments (#74). Thanks @dwieeb.
  • Docs: Add “Advanced Usage” page.

1.0.0 (2015-10-19)


  • Add AIOHTTPParser (#71).
  • Add webargs.async module with AsyncParser.

Bug fixes:

  • If an empty list is passed to a List argument, it will be parsed as an empty list rather than being excluded from the parsed arguments dict (#70). Thanks @mTatcher for catching this.

Other changes:

  • Backwards-incompatible: When decorating resource methods with FalconParser.use_args, the parsed arguments dictionary will be positioned after the request and response arguments.
  • Backwards-incompatible: When decorating views with DjangoParser.use_args, the parsed arguments dictionary will be positioned after the request argument.
  • Backwards-incompatible: Parser.get_request_from_view_args gets passed a view function as its first argument.
  • Backwards-incompatible: Remove logging from default error handlers.

0.18.0 (2015-10-04)


  • Add FalconParser (#63).
  • Add fields.DelimitedList (#66). Thanks @jmcarp.
  • TornadoParser will parse json with simplejson if it is installed.
  • BottleParser caches parsed json per-request for improved performance.

No breaking changes. Yay!

0.17.0 (2015-09-29)


  • TornadoParser returns unicode strings rather than bytestrings (#41). Thanks @thomasboyt for the suggestion.
  • Add Parser.get_default_request and Parser.get_request_from_view_args hooks to simplify Parser implementations.
  • Backwards-compatible: webargs.core.get_value takes a Field as its last argument. Note: this is technically a breaking change, but this won’t affect most users since get_value is only used internally by Parser classes.


  • Add examples/annotations_example.py (demonstrates using Python 3 function annotations to define request arguments).
  • Fix examples. Thanks @hyunchel for catching an error in the Flask error handling docs.

Bug fixes:

  • Correctly pass validate and force_all params to PyramidParser.use_args.

0.16.0 (2015-09-27)

The major change in this release is that webargs now depends on marshmallow for defining arguments and validation.

Your code will need to be updated to use Fields rather than Args.

# Old API
from webargs import Arg

args = {
    'name': Arg(str, required=True)
    'password': Arg(str, validate=lambda p: len(p) >= 6),
    'display_per_page': Arg(int, default=10),
    'nickname': Arg(multiple=True),
    'Content-Type': Arg(dest='content_type', location='headers'),
    'location': Arg({
        'city': Arg(str),
        'state': Arg(str)
    'meta': Arg(dict),

# New API
from webargs import fields

args = {
    'name': fields.Str(required=True)
    'password': fields.Str(validate=lambda p: len(p) >= 6),
    'display_per_page': fields.Int(missing=10),
    'nickname': fields.List(fields.Str()),
    'content_type': fields.Str(load_from='Content-Type'),
    'location': fields.Nested({
        'city': fields.Str(),
        'state': fields.Str()
    'meta': fields.Dict(),


  • Error messages for all arguments are “bundled” (#58).


  • Backwards-incompatible: Replace Args with marshmallow fields (#61).
  • Backwards-incompatible: When using use_kwargs, missing arguments will have the special value missing rather than None.
  • TornadoParser raises a custom HTTPError with a messages attribute when validation fails.

Bug fixes:

  • Fix required validation of nested arguments (#39, #51). These are fixed by virtue of using marshmallow’s Nested field. Thanks @ewang and @chavz for reporting.


  • Updated docs.
  • Add examples/schema_example.py.
  • Tested against Python 3.5.

0.15.0 (2015-08-22)


  • If a parsed argument is None, the type conversion function is not called #54. Thanks @marcellarius.

Bug fixes:

  • Fix parsing nested Args when the argument is missing from the input (#52). Thanks @stas.

0.14.0 (2015-06-28)


  • Add parsing of matchdict to PyramidParser. Thanks @hartror.

Bug fixes:

  • Fix PyramidParser's use_kwargs method (#42). Thanks @hartror for the catch and patch.
  • Correctly use locations passed to Parser’s constructor when using use_args (#44). Thanks @jacebrowning for the catch and patch.
  • Fix behavior of default and dest argument on nested Args (#40 and #46). Thanks @stas.


  • A 422 response is returned to the client when a ValidationError is raised by a parser (#38).

0.13.0 (2015-04-05)


  • Support for webapp2 via the webargs.webapp2parser module. Thanks @Trii.
  • Store argument name on RequiredArgMissingError. Thanks @stas.
  • Allow error messages for required validation to be overriden. Thanks again @stas.


  • Remove source parameter from Arg.

0.12.0 (2015-03-22)


  • Store argument name on ValidationError (#32). Thanks @alexmic for the suggestion. Thanks @stas for the patch.
  • Allow nesting of dict subtypes.

0.11.0 (2015-03-01)


  • Add dest parameter to Arg constructor which determines the key to be added to the parsed arguments dictionary (#32).
  • Backwards-incompatible: Rename targets parameter to locations in Parser constructor, Parser#parse_arg, Parser#parse, Parser#use_args, and Parser#use_kwargs.
  • Backwards-incompatible: Rename Parser#target_handler to Parser#location_handler.


  • The source parameter is deprecated in favor of the dest parameter.

Bug fixes:

  • Fix validate parameter of DjangoParser#use_args.

0.10.0 (2014-12-23)

  • When parsing a nested Arg, filter out extra arguments that are not part of the Arg's nested dict (#28). Thanks Derrick Gilland for the suggestion.
  • Fix bug in parsing Args with both type coercion and multiple=True (#30). Thanks Steven Manuatu for reporting.
  • Raise RequiredArgMissingError when a required argument is missing on a request.

0.9.1 (2014-12-11)

  • Fix behavior of multiple=True when nesting Args (#29). Thanks Derrick Gilland for reporting.

0.9.0 (2014-12-08)

  • Pyramid support thanks to @philtay.
  • User-friendly error messages when Arg type conversion/validation fails. Thanks Andriy Yurchuk.
  • Allow use argument to be a list of functions.
  • Allow Args to be nested within each other, e.g. for nested dict validation. Thanks @saritasa for the suggestion.
  • Backwards-incompatible: Parser will only pass ValidationErrors to its error handler function, rather than catching all generic Exceptions.
  • Backwards-incompatible: Rename Parser.TARGET_MAP to Parser.__target_map__.
  • Add a short-lived cache to the Parser class that can be used to store processed request data for reuse.
  • Docs: Add example usage with Flask-RESTful.

0.8.1 (2014-10-28)

  • Fix bug in TornadoParser that raised an error when request body is not a string (e.g when it is a Future). Thanks Josh Carp.

0.8.0 (2014-10-26)

  • Fix Parser.use_kwargs behavior when an Arg is allowed missing. The allow_missing attribute is ignored when use_kwargs is called.
  • default may be a callable.
  • Allow ValidationError to specify a HTTP status code for the error response.
  • Improved error logging.
  • Add 'query' as a valid target name.
  • Allow a list of validators to be passed to an Arg or Parser.parse.
  • A more useful __repr__ for Arg.
  • Add examples and updated docs.

0.7.0 (2014-10-18)

  • Add source parameter to Arg constructor. Allows renaming of keys in the parsed arguments dictionary. Thanks Josh Carp.
  • FlaskParser's handle_error method attaches the string representation of validation errors on err.data['message']. The raised exception is stored on err.data['exc'].
  • Additional keyword arguments passed to Arg are stored as metadata.

0.6.2 (2014-10-05)

  • Fix bug in TornadoParser's handle_error method. Thanks Josh Carp.
  • Add error parameter to Parser constructor that allows a custom error message to be used if schema-level validation fails.
  • Fix bug that raised a UnicodeEncodeError on Python 2 when an Arg’s validator function received non-ASCII input.

0.6.1 (2014-09-28)

  • Fix regression with parsing an Arg with both default and target set (see issue #11).

0.6.0 (2014-09-23)

  • Add validate parameter to Parser.parse and Parser.use_args. Allows validation of the full parsed output.
  • If allow_missing is True on an Arg for which None is explicitly passed, the value will still be present in the parsed arguments dictionary.
  • Backwards-incompatible: Parser's parse_* methods return webargs.core.Missing if the value cannot be found on the request. NOTE: webargs.core.Missing will not show up in the final output of Parser.parse.
  • Fix bug with parsing empty request bodies with TornadoParser.

0.5.1 (2014-08-30)

  • Fix behavior of Arg's allow_missing parameter when multiple=True.
  • Fix bug in tornadoparser that caused parsing JSON arguments to fail.

0.5.0 (2014-07-27)

  • Fix JSON parsing in Flask parser when Content-Type header contains more than just application/json. Thanks Samir Uppaluru for reporting.
  • Backwards-incompatible: The use parameter to Arg is called before type conversion occurs. Thanks Eric Wang for the suggestion.
  • Tested on Tornado>=4.0.

0.4.0 (2014-05-04)

  • Custom target handlers can be defined using the Parser.target_handler decorator.
  • Error handler can be specified using the Parser.error_handler decorator.
  • Args can define their request target by passing in a target argument.
  • Backwards-incompatible: DEFAULT_TARGETS is now a class member of Parser. This allows subclasses to override it.

0.3.4 (2014-04-27)

  • Fix bug that caused use_args to fail on class-based views in Flask.
  • Add allow_missing parameter to Arg.

0.3.3 (2014-03-20)

  • Awesome contributions from the open-source community!
  • Add use_kwargs decorator. Thanks @venuatu.
  • Tornado support thanks to @jvrsantacruz.
  • Tested on Python 3.4.

0.3.2 (2014-03-04)

  • Fix bug with parsing JSON in Flask and Bottle.

0.3.1 (2014-03-03)

  • Remove print statements in core.py. Oops.

0.3.0 (2014-03-02)

  • Add support for repeated parameters (#1).
  • Backwards-incompatible: All parse_* methods take arg as their fourth argument.
  • Add error_handler param to Parser.

0.2.0 (2014-02-26)

  • Bottle support.
  • Add targets param to Parser. Allows setting default targets.
  • Add files target.

0.1.0 (2014-02-16)

  • First release.
  • Parses JSON, querystring, forms, headers, and cookies.
  • Support for Flask and Django.