Creating or Extending Validator Classes#
- jsonschema.validators.create(meta_schema, validators=(), version=None, type_checker=TypeChecker(_type_checkers=pmap({'integer': <function <lambda>>, 'object': <function is_object>, 'number': <function is_number>, 'boolean': <function is_bool>, 'string': <function is_string>, 'null': <function is_null>, 'array': <function is_array>})), format_checker=<FormatChecker checkers=['date', 'email', 'idn-email', 'idn-hostname', 'ipv4', 'ipv6', 'regex', 'uuid']>, id_of=<function _id_of>, applicable_validators=operator.methodcaller('items'))[source]#
Create a new validator class.
- Parameters:
meta_schema (collections.abc.Mapping) – the meta schema for the new validator class
validators (collections.abc.Mapping) –
a mapping from names to callables, where each callable will validate the schema property with the given name.
Each callable should take 4 arguments:
a validator instance,
the value of the property being validated within the instance
the instance
the schema
version (str) – an identifier for the version that this validator class will validate. If provided, the returned validator class will have its
__name__
set to include the version, and also will havejsonschema.validators.validates
automatically called for the given version.type_checker (jsonschema.TypeChecker) –
a type checker, used when applying the type keyword.
If unprovided, a
jsonschema.TypeChecker
will be created with a set of default types typical of JSON Schema drafts.format_checker (jsonschema.FormatChecker) –
a format checker, used when applying the format keyword.
If unprovided, a
jsonschema.FormatChecker
will be created with a set of default formats typical of JSON Schema drafts.id_of (collections.abc.Callable) – A function that given a schema, returns its ID.
applicable_validators (collections.abc.Callable) – A function that given a schema, returns the list of applicable validators (validation keywords and callables) which will be used to validate the instance.
- Returns:
a new
jsonschema.protocols.Validator
class
- jsonschema.validators.extend(validator, validators=(), version=None, type_checker=None, format_checker=None)[source]#
Create a new validator class by extending an existing one.
- Parameters:
validator (jsonschema.protocols.Validator) – an existing validator class
validators (collections.abc.Mapping) –
a mapping of new validator callables to extend with, whose structure is as in
create
.Note
Any validator callables with the same name as an existing one will (silently) replace the old validator callable entirely, effectively overriding any validation done in the “parent” validator class.
If you wish to instead extend the behavior of a parent’s validator callable, delegate and call it directly in the new validator function by retrieving it using
OldValidator.VALIDATORS["validation_keyword_name"]
.version (str) – a version for the new validator class
type_checker (jsonschema.TypeChecker) –
a type checker, used when applying the type keyword.
If unprovided, the type checker of the extended
jsonschema.protocols.Validator
will be carried along.format_checker (jsonschema.FormatChecker) –
a format checker, used when applying the format keyword.
If unprovided, the format checker of the extended
jsonschema.protocols.Validator
will be carried along.
- Returns:
a new
jsonschema.protocols.Validator
class extending the one provided
Note
Meta Schemas
The new validator class will have its parent’s meta schema.
If you wish to change or extend the meta schema in the new validator class, modify
META_SCHEMA
directly on the returned class. Note that no implicit copying is done, so a copy should likely be made before modifying it, in order to not affect the old validator.
- jsonschema.validators.validator_for(schema, default=<class 'jsonschema.validators.Draft202012Validator'>)[source]#
Retrieve the validator class appropriate for validating the given schema.
Uses the $schema keyword that should be present in the given schema to look up the appropriate validator class.
- Parameters:
schema (collections.abc.Mapping or bool) – the schema to look at
default –
the default to return if the appropriate validator class cannot be determined.
If unprovided, the default is to return the latest supported draft.
- jsonschema.validators.validates(version)[source]#
Register the decorated validator for a
version
of the specification.Registered validators and their meta schemas will be considered when parsing $schema keywords’ URIs.
- Parameters:
version (str) – An identifier to use as the version’s name
- Returns:
a class decorator to decorate the validator with the version
- Return type:
Creating Validation Errors#
Any validating function that validates against a subschema should call
descend
, rather than iter_errors
. If it recurses into the
instance, or schema, it should pass one or both of the path
or
schema_path
arguments to descend
in order to properly maintain
where in the instance or schema respectively the error occurred.
The Validator Protocol#
jsonschema
defines a protocol
,
jsonschema.protocols.Validator
which can be used in type annotations to
describe the type of a validator object.
For full details, see The Validator Protocol.