Creating or Extending Validator Classes¶
-
jsonschema.validators.
create
(meta_schema, validators=(), version=None, default_types=None, type_checker=None, id_of=<function _id_of>)[source]¶ Create a new validator class.
- Parameters
meta_schema (collections.Mapping) – the meta schema for the new validator class
validators (collections.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 validator.
If unprovided, a
jsonschema.TypeChecker
will be created with a set of default types typical of JSON Schema drafts.default_types (collections.Mapping) –
Deprecated since version 3.0.0: Please use the type_checker argument instead.
If set, it provides mappings of JSON types to Python types that will be converted to functions and redefined in this object’s
jsonschema.TypeChecker
.id_of (collections.Callable) – A function that given a schema, returns its ID.
- Returns
a new
jsonschema.IValidator
class
-
jsonschema.validators.
extend
(validator, validators=(), version=None, type_checker=None)[source]¶ Create a new validator class by extending an existing one.
- Parameters
validator (jsonschema.IValidator) – an existing validator class
validators (collections.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["validator_name"]
.version (str) – a version for the new validator class
type_checker (jsonschema.TypeChecker) –
a type checker, used when applying the type validator.
If unprovided, the type checker of the extended
jsonschema.IValidator
will be carried along.`
- Returns
a new
jsonschema.IValidator
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.create.<locals>.Validator'>)[source]¶ Retrieve the validator class appropriate for validating the given schema.
Uses the $schema property that should be present in the given schema to look up the appropriate validator class.
- Parameters
schema (collections.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
properties’ 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.