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"""
Creation and extension of validators, with implementations for existing drafts.
"""
from __future__ import division
from warnings import warn
import contextlib
import json
import numbers
from six import add_metaclass
from jsonschema import (
_legacy_validators,
_types,
_utils,
_validators,
exceptions,
)
from jsonschema.compat import (
Sequence,
int_types,
iteritems,
lru_cache,
str_types,
unquote,
urldefrag,
urljoin,
urlopen,
urlsplit,
)
# Sigh. https://gitlab.com/pycqa/flake8/issues/280
# https://github.com/pyga/ebb-lint/issues/7
# Imported for backwards compatibility.
from jsonschema.exceptions import ErrorTree
ErrorTree
class _DontDoThat(Exception):
"""
Raised when a Validators with non-default type checker is misused.
Asking one for DEFAULT_TYPES doesn't make sense, since type checkers
exist for the unrepresentable cases where DEFAULT_TYPES can't
represent the type relationship.
"""
def __str__(self):
return "DEFAULT_TYPES cannot be used on Validators using TypeCheckers"
validators = {}
meta_schemas = _utils.URIDict()
def _generate_legacy_type_checks(types=()):
"""
Generate newer-style type checks out of JSON-type-name-to-type mappings.
Arguments:
types (dict):
A mapping of type names to their Python types
Returns:
A dictionary of definitions to pass to `TypeChecker`
"""
types = dict(types)
def gen_type_check(pytypes):
pytypes = _utils.flatten(pytypes)
def type_check(checker, instance):
if isinstance(instance, bool):
if bool not in pytypes:
return False
return isinstance(instance, pytypes)
return type_check
definitions = {}
for typename, pytypes in iteritems(types):
definitions[typename] = gen_type_check(pytypes)
return definitions
_DEPRECATED_DEFAULT_TYPES = {
u"array": list,
u"boolean": bool,
u"integer": int_types,
u"null": type(None),
u"number": numbers.Number,
u"object": dict,
u"string": str_types,
}
_TYPE_CHECKER_FOR_DEPRECATED_DEFAULT_TYPES = _types.TypeChecker(
type_checkers=_generate_legacy_type_checks(_DEPRECATED_DEFAULT_TYPES),
)
def validates(version):
"""
Register the decorated validator for a ``version`` of the specification.
Registered validators and their meta schemas will be considered when
parsing ``$schema`` properties' URIs.
Arguments:
version (str):
An identifier to use as the version's name
Returns:
collections.Callable:
a class decorator to decorate the validator with the version
"""
def _validates(cls):
validators[version] = cls
meta_schema_id = cls.ID_OF(cls.META_SCHEMA)
if meta_schema_id:
meta_schemas[meta_schema_id] = cls
return cls
return _validates
def _DEFAULT_TYPES(self):
if self._CREATED_WITH_DEFAULT_TYPES is None:
raise _DontDoThat()
warn(
(
"The DEFAULT_TYPES attribute is deprecated. "
"See the type checker attached to this validator instead."
),
DeprecationWarning,
stacklevel=2,
)
return self._DEFAULT_TYPES
class _DefaultTypesDeprecatingMetaClass(type):
DEFAULT_TYPES = property(_DEFAULT_TYPES)
def _id_of(schema):
if schema is True or schema is False:
return u""
return schema.get(u"$id", u"")
def create(
meta_schema,
validators=(),
version=None,
default_types=None,
type_checker=None,
id_of=_id_of,
):
"""
Create a new validator class.
Arguments:
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:
1. a validator instance,
2. the value of the property being validated within the
instance
3. the instance
4. 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 have `jsonschema.validators.validates` automatically
called for the given version.
type_checker (jsonschema.TypeChecker):
a type checker, used when applying the :validator:`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:: 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
"""
if default_types is not None:
if type_checker is not None:
raise TypeError(
"Do not specify default_types when providing a type checker.",
)
_created_with_default_types = True
warn(
(
"The default_types argument is deprecated. "
"Use the type_checker argument instead."
),
DeprecationWarning,
stacklevel=2,
)
type_checker = _types.TypeChecker(
type_checkers=_generate_legacy_type_checks(default_types),
)
else:
default_types = _DEPRECATED_DEFAULT_TYPES
if type_checker is None:
_created_with_default_types = False
type_checker = _TYPE_CHECKER_FOR_DEPRECATED_DEFAULT_TYPES
elif type_checker is _TYPE_CHECKER_FOR_DEPRECATED_DEFAULT_TYPES:
_created_with_default_types = False
else:
_created_with_default_types = None
@add_metaclass(_DefaultTypesDeprecatingMetaClass)
class Validator(object):
VALIDATORS = dict(validators)
META_SCHEMA = dict(meta_schema)
TYPE_CHECKER = type_checker
ID_OF = staticmethod(id_of)
DEFAULT_TYPES = property(_DEFAULT_TYPES)
_DEFAULT_TYPES = dict(default_types)
_CREATED_WITH_DEFAULT_TYPES = _created_with_default_types
def __init__(
self,
schema,
types=(),
resolver=None,
format_checker=None,
):
if types:
warn(
(
"The types argument is deprecated. Provide "
"a type_checker to jsonschema.validators.extend "
"instead."
),
DeprecationWarning,
stacklevel=2,
)
self.TYPE_CHECKER = self.TYPE_CHECKER.redefine_many(
_generate_legacy_type_checks(types),
)
if resolver is None:
resolver = RefResolver.from_schema(schema, id_of=id_of)
self.resolver = resolver
self.format_checker = format_checker
self.schema = schema
@classmethod
def check_schema(cls, schema):
for error in cls(cls.META_SCHEMA).iter_errors(schema):
raise exceptions.SchemaError.create_from(error)
def iter_errors(self, instance, _schema=None):
if _schema is None:
_schema = self.schema
if _schema is True:
return
elif _schema is False:
yield exceptions.ValidationError(
"False schema does not allow %r" % (instance,),
validator=None,
validator_value=None,
instance=instance,
schema=_schema,
)
return
scope = id_of(_schema)
if scope:
self.resolver.push_scope(scope)
try:
ref = _schema.get(u"$ref")
if ref is not None:
validators = [(u"$ref", ref)]
else:
validators = iteritems(_schema)
for k, v in validators:
validator = self.VALIDATORS.get(k)
if validator is None:
continue
errors = validator(self, v, instance, _schema) or ()
for error in errors:
# set details if not already set by the called fn
error._set(
validator=k,
validator_value=v,
instance=instance,
schema=_schema,
)
if k != u"$ref":
error.schema_path.appendleft(k)
yield error
finally:
if scope:
self.resolver.pop_scope()
def descend(self, instance, schema, path=None, schema_path=None):
for error in self.iter_errors(instance, schema):
if path is not None:
error.path.appendleft(path)
if schema_path is not None:
error.schema_path.appendleft(schema_path)
yield error
def validate(self, *args, **kwargs):
for error in self.iter_errors(*args, **kwargs):
raise error
def is_type(self, instance, type):
try:
return self.TYPE_CHECKER.is_type(instance, type)
except exceptions.UndefinedTypeCheck:
raise exceptions.UnknownType(type, instance, self.schema)
def is_valid(self, instance, _schema=None):
error = next(self.iter_errors(instance, _schema), None)
return error is None
if version is not None:
Validator = validates(version)(Validator)
Validator.__name__ = version.title().replace(" ", "") + "Validator"
return Validator
def extend(validator, validators=(), version=None, type_checker=None):
"""
Create a new validator class by extending an existing one.
Arguments:
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 :validator:`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.
"""
all_validators = dict(validator.VALIDATORS)
all_validators.update(validators)
if type_checker is None:
type_checker = validator.TYPE_CHECKER
elif validator._CREATED_WITH_DEFAULT_TYPES:
raise TypeError(
"Cannot extend a validator created with default_types "
"with a type_checker. Update the validator to use a "
"type_checker when created."
)
return create(
meta_schema=validator.META_SCHEMA,
validators=all_validators,
version=version,
type_checker=type_checker,
id_of=validator.ID_OF,
)
Draft3Validator = create(
meta_schema=_utils.load_schema("draft3"),
validators={
u"$ref": _validators.ref,
u"additionalItems": _validators.additionalItems,
u"additionalProperties": _validators.additionalProperties,
u"dependencies": _legacy_validators.dependencies_draft3,
u"disallow": _legacy_validators.disallow_draft3,
u"divisibleBy": _validators.multipleOf,
u"enum": _validators.enum,
u"extends": _legacy_validators.extends_draft3,
u"format": _validators.format,
u"items": _legacy_validators.items_draft3_draft4,
u"maxItems": _validators.maxItems,
u"maxLength": _validators.maxLength,
u"maximum": _legacy_validators.maximum_draft3_draft4,
u"minItems": _validators.minItems,
u"minLength": _validators.minLength,
u"minimum": _legacy_validators.minimum_draft3_draft4,
u"pattern": _validators.pattern,
u"patternProperties": _validators.patternProperties,
u"properties": _legacy_validators.properties_draft3,
u"type": _legacy_validators.type_draft3,
u"uniqueItems": _validators.uniqueItems,
},
type_checker=_types.draft3_type_checker,
version="draft3",
id_of=lambda schema: schema.get(u"id", ""),
)
Draft4Validator = create(
meta_schema=_utils.load_schema("draft4"),
validators={
u"$ref": _validators.ref,
u"additionalItems": _validators.additionalItems,
u"additionalProperties": _validators.additionalProperties,
u"allOf": _validators.allOf,
u"anyOf": _validators.anyOf,
u"dependencies": _validators.dependencies,
u"enum": _validators.enum,
u"format": _validators.format,
u"items": _legacy_validators.items_draft3_draft4,
u"maxItems": _validators.maxItems,
u"maxLength": _validators.maxLength,
u"maxProperties": _validators.maxProperties,
u"maximum": _legacy_validators.maximum_draft3_draft4,
u"minItems": _validators.minItems,
u"minLength": _validators.minLength,
u"minProperties": _validators.minProperties,
u"minimum": _legacy_validators.minimum_draft3_draft4,
u"multipleOf": _validators.multipleOf,
u"not": _validators.not_,
u"oneOf": _validators.oneOf,
u"pattern": _validators.pattern,
u"patternProperties": _validators.patternProperties,
u"properties": _validators.properties,
u"required": _validators.required,
u"type": _validators.type,
u"uniqueItems": _validators.uniqueItems,
},
type_checker=_types.draft4_type_checker,
version="draft4",
id_of=lambda schema: schema.get(u"id", ""),
)
Draft6Validator = create(
meta_schema=_utils.load_schema("draft6"),
validators={
u"$ref": _validators.ref,
u"additionalItems": _validators.additionalItems,
u"additionalProperties": _validators.additionalProperties,
u"allOf": _validators.allOf,
u"anyOf": _validators.anyOf,
u"const": _validators.const,
u"contains": _validators.contains,
u"dependencies": _validators.dependencies,
u"enum": _validators.enum,
u"exclusiveMaximum": _validators.exclusiveMaximum,
u"exclusiveMinimum": _validators.exclusiveMinimum,
u"format": _validators.format,
u"items": _validators.items,
u"maxItems": _validators.maxItems,
u"maxLength": _validators.maxLength,
u"maxProperties": _validators.maxProperties,
u"maximum": _validators.maximum,
u"minItems": _validators.minItems,
u"minLength": _validators.minLength,
u"minProperties": _validators.minProperties,
u"minimum": _validators.minimum,
u"multipleOf": _validators.multipleOf,
u"not": _validators.not_,
u"oneOf": _validators.oneOf,
u"pattern": _validators.pattern,
u"patternProperties": _validators.patternProperties,
u"properties": _validators.properties,
u"propertyNames": _validators.propertyNames,
u"required": _validators.required,
u"type": _validators.type,
u"uniqueItems": _validators.uniqueItems,
},
type_checker=_types.draft6_type_checker,
version="draft6",
)
Draft7Validator = create(
meta_schema=_utils.load_schema("draft7"),
validators={
u"$ref": _validators.ref,
u"additionalItems": _validators.additionalItems,
u"additionalProperties": _validators.additionalProperties,
u"allOf": _validators.allOf,
u"anyOf": _validators.anyOf,
u"const": _validators.const,
u"contains": _validators.contains,
u"dependencies": _validators.dependencies,
u"enum": _validators.enum,
u"exclusiveMaximum": _validators.exclusiveMaximum,
u"exclusiveMinimum": _validators.exclusiveMinimum,
u"format": _validators.format,
u"if": _validators.if_,
u"items": _validators.items,
u"maxItems": _validators.maxItems,
u"maxLength": _validators.maxLength,
u"maxProperties": _validators.maxProperties,
u"maximum": _validators.maximum,
u"minItems": _validators.minItems,
u"minLength": _validators.minLength,
u"minProperties": _validators.minProperties,
u"minimum": _validators.minimum,
u"multipleOf": _validators.multipleOf,
u"oneOf": _validators.oneOf,
u"not": _validators.not_,
u"pattern": _validators.pattern,
u"patternProperties": _validators.patternProperties,
u"properties": _validators.properties,
u"propertyNames": _validators.propertyNames,
u"required": _validators.required,
u"type": _validators.type,
u"uniqueItems": _validators.uniqueItems,
},
type_checker=_types.draft7_type_checker,
version="draft7",
)
_LATEST_VERSION = Draft7Validator
class RefResolver(object):
"""
Resolve JSON References.
Arguments:
base_uri (str):
The URI of the referring document
referrer:
The actual referring document
store (dict):
A mapping from URIs to documents to cache
cache_remote (bool):
Whether remote refs should be cached after first resolution
handlers (dict):
A mapping from URI schemes to functions that should be used
to retrieve them
urljoin_cache (:func:`functools.lru_cache`):
A cache that will be used for caching the results of joining
the resolution scope to subscopes.
remote_cache (:func:`functools.lru_cache`):
A cache that will be used for caching the results of
resolved remote URLs.
Attributes:
cache_remote (bool):
Whether remote refs should be cached after first resolution
"""
def __init__(
self,
base_uri,
referrer,
store=(),
cache_remote=True,
handlers=(),
urljoin_cache=None,
remote_cache=None,
):
if urljoin_cache is None:
urljoin_cache = lru_cache(1024)(urljoin)
if remote_cache is None:
remote_cache = lru_cache(1024)(self.resolve_from_url)
self.referrer = referrer
self.cache_remote = cache_remote
self.handlers = dict(handlers)
self._scopes_stack = [base_uri]
self.store = _utils.URIDict(
(id, validator.META_SCHEMA)
for id, validator in iteritems(meta_schemas)
)
self.store.update(store)
self.store[base_uri] = referrer
self._urljoin_cache = urljoin_cache
self._remote_cache = remote_cache
@classmethod
def from_schema(cls, schema, id_of=_id_of, *args, **kwargs):
"""
Construct a resolver from a JSON schema object.
Arguments:
schema:
the referring schema
Returns:
`RefResolver`
"""
return cls(base_uri=id_of(schema), referrer=schema, *args, **kwargs)
def push_scope(self, scope):
"""
Enter a given sub-scope.
Treats further dereferences as being performed underneath the
given scope.
"""
self._scopes_stack.append(
self._urljoin_cache(self.resolution_scope, scope),
)
def pop_scope(self):
"""
Exit the most recent entered scope.
Treats further dereferences as being performed underneath the
original scope.
Don't call this method more times than `push_scope` has been
called.
"""
try:
self._scopes_stack.pop()
except IndexError:
raise exceptions.RefResolutionError(
"Failed to pop the scope from an empty stack. "
"`pop_scope()` should only be called once for every "
"`push_scope()`"
)
@property
def resolution_scope(self):
"""
Retrieve the current resolution scope.
"""
return self._scopes_stack[-1]
@property
def base_uri(self):
"""
Retrieve the current base URI, not including any fragment.
"""
uri, _ = urldefrag(self.resolution_scope)
return uri
@contextlib.contextmanager
def in_scope(self, scope):
"""
Temporarily enter the given scope for the duration of the context.
"""
self.push_scope(scope)
try:
yield
finally:
self.pop_scope()
@contextlib.contextmanager
def resolving(self, ref):
"""
Resolve the given ``ref`` and enter its resolution scope.
Exits the scope on exit of this context manager.
Arguments:
ref (str):
The reference to resolve
"""
url, resolved = self.resolve(ref)
self.push_scope(url)
try:
yield resolved
finally:
self.pop_scope()
def resolve(self, ref):
"""
Resolve the given reference.
"""
url = self._urljoin_cache(self.resolution_scope, ref)
return url, self._remote_cache(url)
def resolve_from_url(self, url):
"""
Resolve the given remote URL.
"""
url, fragment = urldefrag(url)
try:
document = self.store[url]
except KeyError:
try:
document = self.resolve_remote(url)
except Exception as exc:
raise exceptions.RefResolutionError(exc)
return self.resolve_fragment(document, fragment)
def resolve_fragment(self, document, fragment):
"""
Resolve a ``fragment`` within the referenced ``document``.
Arguments:
document:
The referent document
fragment (str):
a URI fragment to resolve within it
"""
fragment = fragment.lstrip(u"/")
parts = unquote(fragment).split(u"/") if fragment else []
for part in parts:
part = part.replace(u"~1", u"/").replace(u"~0", u"~")
if isinstance(document, Sequence):
# Array indexes should be turned into integers
try:
part = int(part)
except ValueError:
pass
try:
document = document[part]
except (TypeError, LookupError):
raise exceptions.RefResolutionError(
"Unresolvable JSON pointer: %r" % fragment
)
return document
def resolve_remote(self, uri):
"""
Resolve a remote ``uri``.
If called directly, does not check the store first, but after
retrieving the document at the specified URI it will be saved in
the store if :attr:`cache_remote` is True.
.. note::
If the requests_ library is present, ``jsonschema`` will use it to
request the remote ``uri``, so that the correct encoding is
detected and used.
If it isn't, or if the scheme of the ``uri`` is not ``http`` or
``https``, UTF-8 is assumed.
Arguments:
uri (str):
The URI to resolve
Returns:
The retrieved document
.. _requests: https://pypi.org/project/requests/
"""
try:
import requests
except ImportError:
requests = None
scheme = urlsplit(uri).scheme
if scheme in self.handlers:
result = self.handlers[scheme](uri)
elif scheme in [u"http", u"https"] and requests:
# Requests has support for detecting the correct encoding of
# json over http
result = requests.get(uri).json()
else:
# Otherwise, pass off to urllib and assume utf-8
with urlopen(uri) as url:
result = json.loads(url.read().decode("utf-8"))
if self.cache_remote:
self.store[uri] = result
return result
def validate(instance, schema, cls=None, *args, **kwargs):
"""
Validate an instance under the given schema.
>>> validate([2, 3, 4], {"maxItems": 2})
Traceback (most recent call last):
...
ValidationError: [2, 3, 4] is too long
:func:`validate` will first verify that the provided schema is
itself valid, since not doing so can lead to less obvious error
messages and fail in less obvious or consistent ways.
If you know you have a valid schema already, especially if you
intend to validate multiple instances with the same schema, you
likely would prefer using the `IValidator.validate` method directly
on a specific validator (e.g. ``Draft7Validator.validate``).
Arguments:
instance:
The instance to validate
schema:
The schema to validate with
cls (IValidator):
The class that will be used to validate the instance.
If the ``cls`` argument is not provided, two things will happen
in accordance with the specification. First, if the schema has a
:validator:`$schema` property containing a known meta-schema [#]_
then the proper validator will be used. The specification recommends
that all schemas contain :validator:`$schema` properties for this
reason. If no :validator:`$schema` property is found, the default
validator class is the latest released draft.
Any other provided positional and keyword arguments will be passed
on when instantiating the ``cls``.
Raises:
`jsonschema.exceptions.ValidationError` if the instance
is invalid
`jsonschema.exceptions.SchemaError` if the schema itself
is invalid
.. rubric:: Footnotes
.. [#] known by a validator registered with
`jsonschema.validators.validates`
"""
if cls is None:
cls = validator_for(schema)
cls.check_schema(schema)
validator = cls(schema, *args, **kwargs)
error = exceptions.best_match(validator.iter_errors(instance))
if error is not None:
raise error
def validator_for(schema, default=_LATEST_VERSION):
"""
Retrieve the validator class appropriate for validating the given schema.
Uses the :validator:`$schema` property that should be present in the
given schema to look up the appropriate validator class.
Arguments:
schema (collections.Mapping or bool):
the schema to look at
default:
the default to return if the appropriate validator class
cannot be determined.
If unprovided, the default is to return the latest supported
draft.
"""
if schema is True or schema is False or u"$schema" not in schema:
return default
if schema[u"$schema"] not in meta_schemas:
warn(
(
"The metaschema specified by $schema was not found. "
"Using the latest draft to validate, but this will raise "
"an error in the future."
),
DeprecationWarning,
stacklevel=2,
)
return meta_schemas.get(schema[u"$schema"], _LATEST_VERSION)
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