pydantic

Data validation and settings management using Python type hinting.

Fast and extensible, pydantic plays nicely with your linters/IDE/brain. Define how data should be in pure, canonical Python 3.6+; validate it with pydantic.

Help

See documentation for more details.

Installation

Install using pip install -U pydantic or conda install pydantic -c conda-forge. For more installation options to make pydantic even faster, see the Install section in the documentation.

A Simple Example

from datetime import datetime
from typing import List
from pydantic import BaseModel

class User(BaseModel):
    id: int
    name = 'John Doe'
    signup_ts: datetime = None
    friends: List[int] = []

external_data = {'id': '123', 'signup_ts': '2017-06-01 12:22', 'friends': [1, '2', b'3']}
user = User(**external_data)
print(user)
#> User id=123 name='John Doe' signup_ts=datetime.datetime(2017, 6, 1, 12, 22) friends=[1, 2, 3]
print(user.id)
#> 123

Contributing

For guidance on setting up a development environment and how to make a contribution to pydantic, see Contributing to Pydantic.

v1.1 (2019-11-07)

• Add a mypy plugin for type checking BaseModel.__init__ and more, #722 by @dmontagu
• Change return type typehint for GenericModel.__class_getitem__ to prevent PyCharm warnings, #936 by @dmontagu
• Fix usage of Any to allow None, also support TypeVar thus allowing use of un-parameterised collection types e.g. Dict and List, #962 by @samuelcolvin
• Set FieldInfo on subfields to fix schema generation for complex nested types, #965 by @samuelcolvin

v1.0 (2019-10-23)

• Breaking Change: deprecate the Model.fields property, use Model.__fields__ instead, #883 by @samuelcolvin
• Breaking Change: Change the precedence of aliases so child model aliases override parent aliases, including using alias_generator, #904 by @samuelcolvin
• Breaking change: Rename skip_defaults to exclude_unset, and add ability to exclude actual defaults, #915 by @dmontagu
• Add **kwargs to pydantic.main.ModelMetaclass.__new__ so __init_subclass__ can take custom parameters on extended BaseModel classes, #867 by @retnikt
• Fix field of a type that has a default value, #880 by @koxudaxi
• Use FutureWarning instead of DeprecationWarning when alias instead of env is used for settings models, #881 by @samuelcolvin
• Fix issue with BaseSettings inheritance and alias getting set to None, #882 by @samuelcolvin
• Modify __repr__ and __str__ methods to be consistent across all public classes, add __pretty__ to support python-devtools, #884 by @samuelcolvin
• deprecation warning for case_insensitive on BaseSettings config, #885 by @samuelcolvin
• For BaseSettings merge environment variables and in-code values recursively, as long as they create a valid object when merged together, to allow splitting init arguments, #888 by @idmitrievsky
• change secret types example, #890 by @ashears
• Change the signature of Model.construct() to be more user-friendly, document construct() usage, #898 by @samuelcolvin
• Add example for the construct() method, #907 by @ashears
• Improve use of Field constraints on complex types, raise an error if constraints are not enforceable, also support tuples with an ellipsis Tuple[X, ...], Sequence and FrozenSet in schema, #909 by @samuelcolvin
• update docs for bool missing valid value, #911 by @trim21
• Better str/repr logic for ModelField, #912 by @samuelcolvin
• Fix ConstrainedList, update schema generation to reflect min_items and max_items Field() arguments, #917 by @samuelcolvin
• Allow abstracts sets (eg. dict keys) in the include and exclude arguments of dict(), #921 by @samuelcolvin
• Fix JSON serialization errors on ValidationError.json() by using pydantic_encoder, #922 by @samuelcolvin
• Clarify usage of remove_untouched, improve error message for types with no validators, #926 by @retnikt

v1.0b2 (2019-10-07)

• Mark StrictBool typecheck as bool to allow for default values without mypy errors, #690 by @dmontagu
• Transfer the documentation build from sphinx to mkdocs, re-write much of the documentation, #856 by @samuelcolvin
• Add support for custom naming schemes for GenericModel subclasses, #859 by @dmontagu
• Add if TYPE_CHECKING: to the excluded lines for test coverage, #874 by @dmontagu
• Rename allow_population_by_alias to allow_population_by_field_name, remove unnecessary warning about it, #875 by @samuelcolvin

v1.0b1 (2019-10-01)

• Breaking Change: rename Schema to Field, make it a function to placate mypy, #577 by @samuelcolvin
• Breaking Change: modify parsing behavior for bool, #617 by @dmontagu
• Breaking Change: get_validators is no longer recognised, use __get_validators__. Config.ignore_extra and Config.allow_extra are no longer recognised, use Config.extra, #720 by @samuelcolvin
• Breaking Change: modify default config settings for BaseSettings; case_insensitive renamed to case_sensitive, default changed to case_sensitive = False, env_prefix default changed to '' - e.g. no prefix, #721 by @dmontagu
• Breaking change: Implement root_validator and rename root errors from __obj__ to __root__, #729 by @samuelcolvin
• Breaking Change: alter the behaviour of dict(model) so that sub-models are nolonger converted to dictionaries, #733 by @samuelcolvin
• Breaking change: Added initvars support to post_init_post_parse, #748 by @Raphael-C-Almeida
• Breaking Change: Make BaseModel.json() only serialize the __root__ key for models with custom root, #752 by @dmontagu
• Breaking Change: complete rewrite of URL parsing logic, #755 by @samuelcolvin
• Breaking Change: preserve superclass annotations for field-determination when not provided in subclass, #757 by @dmontagu
• Breaking Change: BaseSettings now uses the special env settings to define which environment variables to read, not aliases, #847 by @samuelcolvin
• add support for assert statements inside validators, #653 by @abdusco
• Update documentation to specify the use of pydantic.dataclasses.dataclass and subclassing pydantic.BaseModel, #710 by @maddosaurus
• Allow custom JSON decoding and encoding via json_loads and json_dumps Config properties, #714 by @samuelcolvin
• make all annotated fields occur in the order declared, #715 by @dmontagu
• use pytest to test mypy integration, #735 by @dmontagu
• add __repr__ method to ErrorWrapper, #738 by @samuelcolvin
• Added support for FrozenSet members in dataclasses, and a better error when attempting to use types from the typing module that are not supported by Pydantic, #745 by @djpetti
• add documentation for Pycharm Plugin, #750 by @koxudaxi
• fix broken examples in the docs, #753 by @dmontagu
• moving typing related objects into pydantic.typing, #761 by @samuelcolvin
• Minor performance improvements to ErrorWrapper, ValidationError and datetime parsing, #763 by @samuelcolvin
• Improvements to datetime/date/time/timedelta types: more descriptive errors, change errors to value_error not type_error, support bytes, #766 by @samuelcolvin
• fix error messages for Literal types with multiple allowed values, #770 by @dmontagu
• Improved auto-generated title field in JSON schema by converting underscore to space, #772 by @skewty
• support mypy --no-implicit-reexport for dataclasses, also respect --no-implicit-reexport in pydantic itself, #783 by @samuelcolvin
• add the PaymentCardNumber type, #790 by @matin
• Fix const validations for lists, #794 by @hmvp
• Set additionalProperties to false in schema for models with extra fields disallowed, #796 by @Code0x58
• EmailStr validation method now returns local part case-sensitive per RFC 5321, #798 by @henriklindgren
• Added ability to validate strictness to ConstrainedFloat, ConstrainedInt and ConstrainedStr and added StrictFloat and StrictInt classes, #799 by @DerRidda
• Improve handling of None and Optional, replace whole with each_item (inverse meaning, default False) on validators, #803 by @samuelcolvin
• add support for Type[T] type hints, #807 by @timonbimon
• Performance improvements from removing change_exceptions, change how pydantic error are constructed, #819 by @samuelcolvin
• Fix the error message arising when a BaseModel-type model field causes a ValidationError during parsing, #820 by @dmontagu
• allow getter_dict on Config, modify GetterDict to be more like a Mapping object and thus easier to work with, #821 by @samuelcolvin
• Only check TypeVar param on base GenericModel class, #842 by @zpencerq
• rename Model._schema_cache -> Model.__schema_cache__, Model._json_encoder -> Model.__json_encoder__, Model._custom_root_type -> Model.__custom_root_type__, #851 by @samuelcolvin

v0.32.2 (2019-08-17)

• fix __post_init__ usage with dataclass inheritance, fix #739 by @samuelcolvin
• fix required fields validation on GenericModels classes, #742 by @amitbl
• fix defining custom Schema on GenericModel fields, #754 by @amitbl

v0.32.1 (2019-08-08)

• do not validate extra fields when validate_assignment is on, #724 by @YaraslauZhylko

v0.32 (2019-08-06)

• add model name to ValidationError error message, #676 by @dmontagu
• breaking change: remove __getattr__ and rename __values__ to __dict__ on BaseModel, deprecation warning on use __values__ attr, attributes access speed increased up to 14 times, #712 by @MrMrRobat
• support ForwardRef (without self-referencing annotations) in Python 3.6, #706 by @koxudaxi
• implement schema_extra in Config sub-class, #663 by @tiangolo

v0.31.1 (2019-07-31)

• fix json generation for EnumError, #697 by @dmontagu
• update numerous dependencies

v0.31 (2019-07-24)

• better support for floating point multiple_of values, #652 by @justindujardin
• fix schema generation for NewType and Literal, #649 by @dmontagu
• fix alias_generator and field config conflict, #645 by @gmetzker and #658 by @MrMrRobat
• more detailed message for EnumError, #673 by @dmontagu
• add advanced exclude support for dict, json and copy, #648 by @MrMrRobat
• fix bug in GenericModel for models with concrete parameterized fields, #672 by @dmontagu
• add documentation for Literal type, #651 by @dmontagu
• add Config.keep_untouched for custom descriptors support, #679 by @MrMrRobat
• use inspect.cleandoc internally to get model description, #657 by @tiangolo
• add Color to schema generation, by @euri10
• add documentation for Literal type, #651 by @dmontagu

v0.30.1 (2019-07-15)

• fix so nested classes which inherit and change __init__ are correctly processed while still allowing self as a parameter, #644 by @lnaden and @dgasmith

v0.30 (2019-07-07)

• enforce single quotes in code, #612 by @samuelcolvin
• fix infinite recursion with dataclass inheritance and __post_init__, #606 by @Hanaasagi
• fix default values for GenericModel, #610 by @dmontagu
• clarify that self-referencing models require python 3.7+, #616 by @vlcinsky
• fix truncate for types, #611 by @dmontagu
• add alias_generator support, #622 by @MrMrRobat
• fix unparameterized generic type schema generation, #625 by @dmontagu
• fix schema generation with multiple/circular references to the same model, #621 by @tiangolo and @wongpat
• support custom root types, #628 by @koxudaxi
• support self as a field name in parse_obj, #632 by @samuelcolvin

v0.29 (2019-06-19)

• support dataclasses.InitVar, #592 by @pfrederiks
• Updated documentation to elucidate the usage of Union when defining multiple types under an attribute's annotation and showcase how the type-order can affect marshalling of provided values, #594 by @somada141
• add conlist type, #583 by @hmvp
• add support for generics, #595 by @dmontagu

v0.28 (2019-06-06)

• fix support for JSON Schema generation when using models with circular references in Python 3.7, #572 by @tiangolo
• support __post_init_post_parse__ on dataclasses, #567 by @sevaho
• allow dumping dataclasses to JSON, #575 by @samuelcolvin and @DanielOberg
• ORM mode, #562 by @samuelcolvin
• fix pydantic.compiled on ipython, #573 by @dmontagu and @samuelcolvin
• add StrictBool type, #579 by @cazgp

v0.27 (2019-05-30)

• breaking change _pydantic_post_init to execute dataclass' original __post_init__ before validation, #560 by @HeavenVolkoff
• fix handling of generic types without specified parameters, #550 by @dmontagu
• breaking change (maybe): this is the first release compiled with cython, see the docs and please submit an issue if you run into problems

v0.27.0a1 (2019-05-26)

• fix JSON Schema for list, tuple, and set, #540 by @tiangolo
• compiling with cython, manylinux binaries, some other performance improvements, #548 by @samuelcolvin

v0.26 (2019-05-22)

• fix to schema generation for IPvAnyAddress, IPvAnyInterface, IPvAnyNetwork #498 by @pilosus
• fix variable length tuples support, #495 by @pilosus
• fix return type hint for create_model, #526 by @dmontagu
• Breaking Change: fix .dict(skip_keys=True) skipping values set via alias (this involves changing validate_model() to always returns Tuple[Dict[str, Any], Set[str], Optional[ValidationError]]), #517 by @sommd
• fix to schema generation for IPv4Address, IPv6Address, IPv4Interface, IPv6Interface, IPv4Network, IPv6Network #532 by @euri10
• add Color type, #504 by @pilosus and @samuelcolvin

v0.25 (2019-05-05)

• Improve documentation on self-referencing models and annotations, #487 by @theenglishway
• fix .dict() with extra keys, #490 by @JaewonKim
• support const keyword in Schema, #434 by @Sean1708

v0.24 (2019-04-23)

• fix handling ForwardRef in sub-types, like Union, #464 by @tiangolo
• fix secret serialization, #465 by @atheuz
• Support custom validators for dataclasses, #454 by @primal100
• fix parse_obj to cope with dict-like objects, #472 by @samuelcolvin
• fix to schema generation in nested dataclass-based models, #474 by @NoAnyLove
• fix json for Path, FilePath, and DirectoryPath objects, #473 by @mikegoodspeed

v0.23 (2019-04-04)

• improve documentation for contributing section, #441 by @pilosus
• improve README.rst to include essential information about the package, #446 by @pilosus
• IntEnum support, #444 by @potykion
• fix PyObject callable value, #409 by @pilosus
• fix black deprecation warnings after update, #451 by @pilosus
• fix ForwardRef collection bug, #450 by @tigerwings
• Support specialized ClassVars, #455 by @tyrylu
• fix JSON serialization for ipaddress types, #333 by @pilosus
• add SecretStr and SecretBytes types, #452 by @atheuz

v0.22 (2019-03-29)

• add IPv{4,6,Any}Network and IPv{4,6,Any}Interface types from ipaddress stdlib, #333 by @pilosus
• add docs for datetime types, #386 by @pilosus
• fix to schema generation in dataclass-based models, #408 by @pilosus
• fix path in nested models, #437 by @kataev
• add Sequence support, #304 by @pilosus

v0.21.0 (2019-03-15)

• fix typo in NoneIsNotAllowedError message, #414 by @YaraslauZhylko
• add IPvAnyAddress, IPv4Address and IPv6Address types, #333 by @pilosus

v0.20.1 (2019-02-26)

• fix type hints of parse_obj and similar methods, #405 by @erosennin
• fix submodel validation, #403 by @samuelcolvin
• correct type hints for ValidationError.json, #406 by @layday

v0.20.0 (2019-02-18)

• fix tests for python 3.8, #396 by @samuelcolvin
• Adds fields to the dir method for autocompletion in interactive sessions, #398 by @dgasmith
• support ForwardRef (and therefore from __future__ import annotations) with dataclasses, #397 by @samuelcolvin

v0.20.0a1 (2019-02-13)

• breaking change (maybe): more sophisticated argument parsing for validators, any subset of values, config and field is now permitted, eg. (cls, value, field), however the variadic key word argument ("**kwargs") must be called kwargs, #388 by @samuelcolvin
• breaking change: Adds skip_defaults argument to BaseModel.dict() to allow skipping of fields that were not explicitly set, signature of Model.construct() changed, #389 by @dgasmith
• add py.typed marker file for PEP-561 support, #391 by @je-l
• Fix extra behaviour for multiple inheritance/mix-ins, #394 by @YaraslauZhylko

v0.19.0 (2019-02-04)

• Support Callable type hint, fix #279 by @proofit404
• Fix schema for fields with validator decorator, fix #375 by @tiangolo
• Add multiple_of constraint to ConstrainedDecimal, ConstrainedFloat, ConstrainedInt and their related types condecimal, confloat, and conint #371, thanks @StephenBrown2
• Deprecated ignore_extra and allow_extra Config fields in favor of extra, #352 by @liiight
• Add type annotations to all functions, test fully with mypy, #373 by @samuelcolvin
• fix for 'missing' error with validate_all or validate_always, #381 by @samuelcolvin
• Change the second/millisecond watershed for date/datetime parsing to 2e10, #385 by @samuelcolvin

v0.18.2 (2019-01-22)

• Fix to schema generation with Optional fields, fix #361 by @samuelcolvin

v0.18.1 (2019-01-17)

• add ConstrainedBytes and conbytes types, #315 @Gr1N
• adding MANIFEST.in to include license in package .tar.gz, #358 by @samuelcolvin

v0.18.0 (2019-01-13)

• breaking change: don't call validators on keys of dictionaries, #254 by @samuelcolvin
• Fix validators with always=True when the default is None or the type is optional, also prevent whole validators being called for sub-fields, fix #132 by @samuelcolvin
• improve documentation for settings priority and allow it to be easily changed, #343 by @samuelcolvin
• fix ignore_extra=False and allow_population_by_alias=True, fix #257 by @samuelcolvin
• breaking change: Set BaseConfig attributes min_anystr_length and max_anystr_length to None by default, fix #349 in #350 by @tiangolo
• add support for postponed annotations, #348 by @samuelcolvin

v0.17.0 (2018-12-27)

• fix schema for timedelta as number, #325 by @tiangolo
• prevent validators being called repeatedly after inheritance, #327 by @samuelcolvin
• prevent duplicate validator check in ipython, fix #312 by @samuelcolvin
• add "Using Pydantic" section to docs, #323 by @tiangolo & #326 by @samuelcolvin
• fix schema generation for fields annotated as : dict, : list, : tuple and : set, #330 & #335 by @nkonin
• add support for constrained strings as dict keys in schema, #332 by @tiangolo
• support for passing Config class in dataclasses decorator, #276 by @jarekkar (breaking change: this supersedes the validate_assignment argument with config)
• support for nested dataclasses, #334 by @samuelcolvin
• better errors when getting an ImportError with PyObject, #309 by @samuelcolvin
• rename get_validators to __get_validators__, deprecation warning on use of old name, #338 by @samuelcolvin
• support ClassVar by excluding such attributes from fields, #184 by @samuelcolvin

v0.16.1 (2018-12-10)

• fix create_model to correctly use the passed __config__, #320 by @hugoduncan

v0.16.0 (2018-12-03)

• breaking change: refactor schema generation to be compatible with JSON Schema and OpenAPI specs, #308 by @tiangolo
• add schema to schema module to generate top-level schemas from base models, #308 by @tiangolo
• add additional fields to Schema class to declare validation for str and numeric values, #311 by @tiangolo
• rename _schema to schema on fields, #318 by @samuelcolvin
• add case_insensitive option to BaseSettings Config, #277 by @jasonkuhrt

v0.15.0 (2018-11-18)

• move codebase to use black, #287 by @samuelcolvin
• fix alias use in settings, #286 by @jasonkuhrt and @samuelcolvin
• fix datetime parsing in parse_date, #298 by @samuelcolvin
• allow dataclass inheritance, fix #293 by @samuelcolvin
• fix PyObject = None, fix #305 by @samuelcolvin
• allow Pattern type, fix #303 by @samuelcolvin

v0.14.0 (2018-10-02)

• dataclasses decorator, #269 by @Gaunt and @samuelcolvin

v0.13.1 (2018-09-21)

• fix issue where int_validator doesn't cast a bool to an int #264 by @nphyatt
• add deep copy support for BaseModel.copy() #249, @gangefors

v0.13.0 (2018-08-25)

• raise an exception if a field's name shadows an existing BaseModel attribute #242
• add UrlStr and urlstr types #236
• timedelta json encoding ISO8601 and total seconds, custom json encoders #247, by @cfkanesan and @samuelcolvin
• allow timedelta objects as values for properties of type timedelta (matches datetime etc. behavior) #247

v0.12.1 (2018-07-31)

• fix schema generation for fields defined using typing.Any #237

v0.12.0 (2018-07-31)

• add by_alias argument in .dict() and .json() model methods #205
• add Json type support #214
• support tuples #227
• major improvements and changes to schema #213

v0.11.2 (2018-07-05)

• add NewType support #115
• fix list, set & tuple validation #225
• separate out validate_model method, allow errors to be returned along with valid values #221

v0.11.1 (2018-07-02)

• support Python 3.7 #216, thanks @layday
• Allow arbitrary types in model #209, thanks @oldPadavan

v0.11.0 (2018-06-28)

• make list, tuple and set types stricter #86
• breaking change: remove msgpack parsing #201
• add FilePath and DirectoryPath types #10
• model schema generation #190
• JSON serialisation of models and schemas #133

v0.10.0 (2018-06-11)

• add Config.allow_population_by_alias #160, thanks @bendemaree
• breaking change: new errors format #179, thanks @Gr1N
• breaking change: removed Config.min_number_size and Config.max_number_size #183, thanks @Gr1N
• breaking change: correct behaviour of lt and gt arguments to conint etc. #188 for the old behaviour use le and ge #194, thanks @jaheba
• added error context and ability to redefine error message templates using Config.error_msg_templates #183, thanks @Gr1N
• fix typo in validator exception #150
• copy defaults to model values, so different models don't share objects #154

v0.9.1 (2018-05-10)

• allow custom get_field_config on config classes #159
• add UUID1, UUID3, UUID4 and UUID5 types #167, thanks @Gr1N
• modify some inconsistent docstrings and annotations #173, thanks @YannLuo
• fix type annotations for exotic types #171, thanks @Gr1N
• re-use type validators in exotic types #171
• scheduled monthly requirements updates #168
• add Decimal, ConstrainedDecimal and condecimal types #170, thanks @Gr1N

v0.9.0 (2018-04-28)

• tweak email-validator import error message #145
• fix parse error of parse_date() and parse_datetime() when input is 0 #144, thanks @YannLuo
• add Config.anystr_strip_whitespace and strip_whitespace kwarg to constr, by default values is False #163, thanks @Gr1N
• add ConstrainedFloat, confloat, PositiveFloat and NegativeFloat types #166, thanks @Gr1N

v0.8.0 (2018-03-25)

• fix type annotation for inherit_config #139
• breaking change: check for invalid field names in validators #140
• validate attributes of parent models #141
• breaking change: email validation now uses email-validator #142

v0.7.1 (2018-02-07)

• fix bug with create_model modifying the base class

v0.7.0 (2018-02-06)

• added compatibility with abstract base classes (ABCs) #123
• add create_model method #113 #125
• breaking change: rename .config to .__config__ on a model
• breaking change: remove deprecated .values() on a model, use .dict() instead
• remove use of OrderedDict and use simple dict #126
• add Config.use_enum_values #127
• add wildcard validators of the form @validate('*') #128

v0.6.4 (2018-02-01)

• allow python date and times objects #122

v0.6.3 (2017-11-26)

• fix direct install without README.rst present

v0.6.2 (2017-11-13)

• errors for invalid validator use
• safer check for complex models in Settings

v0.6.1 (2017-11-08)

• prevent duplicate validators, #101
• add always kwarg to validators, #102

v0.6.0 (2017-11-07)

• assignment validation #94, thanks petroswork!
• JSON in environment variables for complex types, #96
• add validator decorators for complex validation, #97
• depreciate values(...) and replace with .dict(...), #99

v0.5.0 (2017-10-23)

• add UUID validation #89
• remove index and track from error object (json) if they're null #90
• improve the error text when a list is provided rather than a dict #90
• add benchmarks table to docs #91

v0.4.0 (2017-07-08)

• show length in string validation error
• fix aliases in config during inheritance #55
• simplify error display
• use unicode ellipsis in truncate
• add parse_obj, parse_raw and parse_file helper functions #58
• switch annotation only fields to come first in fields list not last

v0.3.0 (2017-06-21)

• immutable models via config.allow_mutation = False, associated cleanup and performance improvement #44
• immutable helper methods construct() and copy() #53
• allow pickling of models #53
• setattr is removed as __setattr__ is now intelligent #44
• raise_exception removed, Models now always raise exceptions #44
• instance method validators removed
• django-restful-framework benchmarks added #47
• fix inheritance bug #49
• make str type stricter so list, dict etc are not coerced to strings. #52
• add StrictStr which only always strings as input #52

v0.2.1 (2017-06-07)

• pypi and travis together messed up the deploy of v0.2 this should fix it

v0.2.0 (2017-06-07)

• breaking change: values() on a model is now a method not a property, takes include and exclude arguments
• allow annotation only fields to support mypy
• add pretty to_string(pretty=True) method for models

v0.1.0 (2017-06-03)

• add docs
• add history