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bazarr/libs/jsonschema/validators.py

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Added Swagger documentation for Bazarr API
2022-09-22 03:51:34 +00:00
"""
Creation and extension of validators, with implementations for existing drafts.
"""
from __future__ import annotations
from collections import deque
from collections.abc import Sequence
from functools import lru_cache
from operator import methodcaller
from urllib.parse import unquote, urldefrag, urljoin, urlsplit
from urllib.request import urlopen
from warnings import warn
import contextlib
import json
import reprlib
import typing
import warnings
import attr
from jsonschema import (
_format,
_legacy_validators,
_types,
_utils,
_validators,
exceptions,
)
_UNSET = _utils.Unset()
_VALIDATORS: dict[str, typing.Any] = {}
_META_SCHEMAS = _utils.URIDict()
_VOCABULARIES: list[tuple[str, typing.Any]] = []
def __getattr__(name):
if name == "ErrorTree":
warnings.warn(
"Importing ErrorTree from jsonschema.validators is deprecated. "
"Instead import it from jsonschema.exceptions.",
DeprecationWarning,
stacklevel=2,
)
from jsonschema.exceptions import ErrorTree
return ErrorTree
elif name == "validators":
warnings.warn(
"Accessing jsonschema.validators.validators is deprecated. "
"Use jsonschema.validators.validator_for with a given schema.",
DeprecationWarning,
stacklevel=2,
)
return _VALIDATORS
elif name == "meta_schemas":
warnings.warn(
"Accessing jsonschema.validators.meta_schemas is deprecated. "
"Use jsonschema.validators.validator_for with a given schema.",
DeprecationWarning,
stacklevel=2,
)
return _META_SCHEMAS
raise AttributeError(f"module {__name__} has no attribute {name}")
def validates(version):
"""
Register the decorated validator for a ``version`` of the specification.
Registered validators and their meta schemas will be considered when
parsing :kw:`$schema` keywords' URIs.
Arguments:
version (str):
An identifier to use as the version's name
Returns:
collections.abc.Callable:
a class decorator to decorate the validator with the version
"""
def _validates(cls):
_VALIDATORS[version] = cls
meta_schema_id = cls.ID_OF(cls.META_SCHEMA)
_META_SCHEMAS[meta_schema_id] = cls
return cls
return _validates
def _id_of(schema):
"""
Return the ID of a schema for recent JSON Schema drafts.
"""
if schema is True or schema is False:
return ""
return schema.get("$id", "")
def _store_schema_list():
if not _VOCABULARIES:
_VOCABULARIES.extend(_utils.load_schema("vocabularies").items())
return [
(id, validator.META_SCHEMA) for id, validator in _META_SCHEMAS.items()
] + _VOCABULARIES
def create(
meta_schema,
validators=(),
version=None,
type_checker=_types.draft202012_type_checker,
format_checker=_format.draft202012_format_checker,
id_of=_id_of,
applicable_validators=methodcaller("items"),
):
"""
Create a new validator class.
Arguments:
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:
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 :kw:`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 :kw:`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
"""
# preemptively don't shadow the `Validator.format_checker` local
format_checker_arg = format_checker
@attr.s
class Validator:
VALIDATORS = dict(validators)
META_SCHEMA = dict(meta_schema)
TYPE_CHECKER = type_checker
FORMAT_CHECKER = format_checker_arg
ID_OF = staticmethod(id_of)
schema = attr.ib(repr=reprlib.repr)
resolver = attr.ib(default=None, repr=False)
format_checker = attr.ib(default=None)
def __init_subclass__(cls):
warnings.warn(
(
"Subclassing validator classes is not intended to "
"be part of their public API. A future version "
"will make doing so an error, as the behavior of "
"subclasses isn't guaranteed to stay the same "
"between releases of jsonschema. Instead, prefer "
"composition of validators, wrapping them in an object "
"owned entirely by the downstream library."
),
DeprecationWarning,
stacklevel=2,
)
def __attrs_post_init__(self):
if self.resolver is None:
self.resolver = RefResolver.from_schema(
self.schema,
id_of=id_of,
)
@classmethod
def check_schema(cls, schema):
Validator = validator_for(cls.META_SCHEMA, default=cls)
for error in Validator(cls.META_SCHEMA).iter_errors(schema):
raise exceptions.SchemaError.create_from(error)
def evolve(self, **changes):
# Essentially reproduces attr.evolve, but may involve instantiating
# a different class than this one.
cls = self.__class__
schema = changes.setdefault("schema", self.schema)
NewValidator = validator_for(schema, default=cls)
for field in attr.fields(cls):
if not field.init:
continue
attr_name = field.name # To deal with private attributes.
init_name = attr_name if attr_name[0] != "_" else attr_name[1:]
if init_name not in changes:
changes[init_name] = getattr(self, attr_name)
return NewValidator(**changes)
def iter_errors(self, instance, _schema=None):
if _schema is not None:
warnings.warn(
(
"Passing a schema to Validator.iter_errors "
"is deprecated and will be removed in a future "
"release. Call validator.evolve(schema=new_schema)."
"iter_errors(...) instead."
),
DeprecationWarning,
stacklevel=2,
)
else:
_schema = self.schema
if _schema is True:
return
elif _schema is False:
yield exceptions.ValidationError(
f"False schema does not allow {instance!r}",
validator=None,
validator_value=None,
instance=instance,
schema=_schema,
)
return
scope = id_of(_schema)
if scope:
self.resolver.push_scope(scope)
try:
for k, v in applicable_validators(_schema):
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,
type_checker=self.TYPE_CHECKER,
)
if k not in {"if", "$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.evolve(schema=schema).iter_errors(instance):
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):
if _schema is not None:
warnings.warn(
(
"Passing a schema to Validator.is_valid is deprecated "
"and will be removed in a future release. Call "
"validator.evolve(schema=new_schema).is_valid(...) "
"instead."
),
DeprecationWarning,
stacklevel=2,
)
self = self.evolve(schema=_schema)
error = next(self.iter_errors(instance), None)
return error is None
if version is not None:
safe = version.title().replace(" ", "").replace("-", "")
Validator.__name__ = Validator.__qualname__ = f"{safe}Validator"
Validator = validates(version)(Validator)
return Validator
def extend(
validator,
validators=(),
version=None,
type_checker=None,
format_checker=None,
):
"""
Create a new validator class by extending an existing one.
Arguments:
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 :kw:`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 :kw:`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.
"""
all_validators = dict(validator.VALIDATORS)
all_validators.update(validators)
if type_checker is None:
type_checker = validator.TYPE_CHECKER
if format_checker is None:
format_checker = validator.FORMAT_CHECKER
return create(
meta_schema=validator.META_SCHEMA,
validators=all_validators,
version=version,
type_checker=type_checker,
format_checker=format_checker,
id_of=validator.ID_OF,
)
Draft3Validator = create(
meta_schema=_utils.load_schema("draft3"),
validators={
"$ref": _validators.ref,
"additionalItems": _validators.additionalItems,
"additionalProperties": _validators.additionalProperties,
"dependencies": _legacy_validators.dependencies_draft3,
"disallow": _legacy_validators.disallow_draft3,
"divisibleBy": _validators.multipleOf,
"enum": _validators.enum,
"extends": _legacy_validators.extends_draft3,
"format": _validators.format,
"items": _legacy_validators.items_draft3_draft4,
"maxItems": _validators.maxItems,
"maxLength": _validators.maxLength,
"maximum": _legacy_validators.maximum_draft3_draft4,
"minItems": _validators.minItems,
"minLength": _validators.minLength,
"minimum": _legacy_validators.minimum_draft3_draft4,
"pattern": _validators.pattern,
"patternProperties": _validators.patternProperties,
"properties": _legacy_validators.properties_draft3,
"type": _legacy_validators.type_draft3,
"uniqueItems": _validators.uniqueItems,
},
type_checker=_types.draft3_type_checker,
format_checker=_format.draft3_format_checker,
version="draft3",
id_of=lambda schema: schema.get("id", ""),
applicable_validators=_legacy_validators.ignore_ref_siblings,
)
Draft4Validator = create(
meta_schema=_utils.load_schema("draft4"),
validators={
"$ref": _validators.ref,
"additionalItems": _validators.additionalItems,
"additionalProperties": _validators.additionalProperties,
"allOf": _validators.allOf,
"anyOf": _validators.anyOf,
"dependencies": _legacy_validators.dependencies_draft4_draft6_draft7,
"enum": _validators.enum,
"format": _validators.format,
"items": _legacy_validators.items_draft3_draft4,
"maxItems": _validators.maxItems,
"maxLength": _validators.maxLength,
"maxProperties": _validators.maxProperties,
"maximum": _legacy_validators.maximum_draft3_draft4,
"minItems": _validators.minItems,
"minLength": _validators.minLength,
"minProperties": _validators.minProperties,
"minimum": _legacy_validators.minimum_draft3_draft4,
"multipleOf": _validators.multipleOf,
"not": _validators.not_,
"oneOf": _validators.oneOf,
"pattern": _validators.pattern,
"patternProperties": _validators.patternProperties,
"properties": _validators.properties,
"required": _validators.required,
"type": _validators.type,
"uniqueItems": _validators.uniqueItems,
},
type_checker=_types.draft4_type_checker,
format_checker=_format.draft4_format_checker,
version="draft4",
id_of=lambda schema: schema.get("id", ""),
applicable_validators=_legacy_validators.ignore_ref_siblings,
)
Draft6Validator = create(
meta_schema=_utils.load_schema("draft6"),
validators={
"$ref": _validators.ref,
"additionalItems": _validators.additionalItems,
"additionalProperties": _validators.additionalProperties,
"allOf": _validators.allOf,
"anyOf": _validators.anyOf,
"const": _validators.const,
"contains": _legacy_validators.contains_draft6_draft7,
"dependencies": _legacy_validators.dependencies_draft4_draft6_draft7,
"enum": _validators.enum,
"exclusiveMaximum": _validators.exclusiveMaximum,
"exclusiveMinimum": _validators.exclusiveMinimum,
"format": _validators.format,
"items": _legacy_validators.items_draft6_draft7_draft201909,
"maxItems": _validators.maxItems,
"maxLength": _validators.maxLength,
"maxProperties": _validators.maxProperties,
"maximum": _validators.maximum,
"minItems": _validators.minItems,
"minLength": _validators.minLength,
"minProperties": _validators.minProperties,
"minimum": _validators.minimum,
"multipleOf": _validators.multipleOf,
"not": _validators.not_,
"oneOf": _validators.oneOf,
"pattern": _validators.pattern,
"patternProperties": _validators.patternProperties,
"properties": _validators.properties,
"propertyNames": _validators.propertyNames,
"required": _validators.required,
"type": _validators.type,
"uniqueItems": _validators.uniqueItems,
},
type_checker=_types.draft6_type_checker,
format_checker=_format.draft6_format_checker,
version="draft6",
applicable_validators=_legacy_validators.ignore_ref_siblings,
)
Draft7Validator = create(
meta_schema=_utils.load_schema("draft7"),
validators={
"$ref": _validators.ref,
"additionalItems": _validators.additionalItems,
"additionalProperties": _validators.additionalProperties,
"allOf": _validators.allOf,
"anyOf": _validators.anyOf,
"const": _validators.const,
"contains": _legacy_validators.contains_draft6_draft7,
"dependencies": _legacy_validators.dependencies_draft4_draft6_draft7,
"enum": _validators.enum,
"exclusiveMaximum": _validators.exclusiveMaximum,
"exclusiveMinimum": _validators.exclusiveMinimum,
"format": _validators.format,
"if": _validators.if_,
"items": _legacy_validators.items_draft6_draft7_draft201909,
"maxItems": _validators.maxItems,
"maxLength": _validators.maxLength,
"maxProperties": _validators.maxProperties,
"maximum": _validators.maximum,
"minItems": _validators.minItems,
"minLength": _validators.minLength,
"minProperties": _validators.minProperties,
"minimum": _validators.minimum,
"multipleOf": _validators.multipleOf,
"not": _validators.not_,
"oneOf": _validators.oneOf,
"pattern": _validators.pattern,
"patternProperties": _validators.patternProperties,
"properties": _validators.properties,
"propertyNames": _validators.propertyNames,
"required": _validators.required,
"type": _validators.type,
"uniqueItems": _validators.uniqueItems,
},
type_checker=_types.draft7_type_checker,
format_checker=_format.draft7_format_checker,
version="draft7",
applicable_validators=_legacy_validators.ignore_ref_siblings,
)
Draft201909Validator = create(
meta_schema=_utils.load_schema("draft2019-09"),
validators={
"$recursiveRef": _legacy_validators.recursiveRef,
"$ref": _validators.ref,
"additionalItems": _validators.additionalItems,
"additionalProperties": _validators.additionalProperties,
"allOf": _validators.allOf,
"anyOf": _validators.anyOf,
"const": _validators.const,
"contains": _validators.contains,
"dependentRequired": _validators.dependentRequired,
"dependentSchemas": _validators.dependentSchemas,
"enum": _validators.enum,
"exclusiveMaximum": _validators.exclusiveMaximum,
"exclusiveMinimum": _validators.exclusiveMinimum,
"format": _validators.format,
"if": _validators.if_,
"items": _legacy_validators.items_draft6_draft7_draft201909,
"maxItems": _validators.maxItems,
"maxLength": _validators.maxLength,
"maxProperties": _validators.maxProperties,
"maximum": _validators.maximum,
"minItems": _validators.minItems,
"minLength": _validators.minLength,
"minProperties": _validators.minProperties,
"minimum": _validators.minimum,
"multipleOf": _validators.multipleOf,
"not": _validators.not_,
"oneOf": _validators.oneOf,
"pattern": _validators.pattern,
"patternProperties": _validators.patternProperties,
"properties": _validators.properties,
"propertyNames": _validators.propertyNames,
"required": _validators.required,
"type": _validators.type,
"unevaluatedItems": _legacy_validators.unevaluatedItems_draft2019,
"unevaluatedProperties": _validators.unevaluatedProperties,
"uniqueItems": _validators.uniqueItems,
},
type_checker=_types.draft201909_type_checker,
format_checker=_format.draft201909_format_checker,
version="draft2019-09",
)
Draft202012Validator = create(
meta_schema=_utils.load_schema("draft2020-12"),
validators={
"$dynamicRef": _validators.dynamicRef,
"$ref": _validators.ref,
"additionalItems": _validators.additionalItems,
"additionalProperties": _validators.additionalProperties,
"allOf": _validators.allOf,
"anyOf": _validators.anyOf,
"const": _validators.const,
"contains": _validators.contains,
"dependentRequired": _validators.dependentRequired,
"dependentSchemas": _validators.dependentSchemas,
"enum": _validators.enum,
"exclusiveMaximum": _validators.exclusiveMaximum,
"exclusiveMinimum": _validators.exclusiveMinimum,
"format": _validators.format,
"if": _validators.if_,
"items": _validators.items,
"maxItems": _validators.maxItems,
"maxLength": _validators.maxLength,
"maxProperties": _validators.maxProperties,
"maximum": _validators.maximum,
"minItems": _validators.minItems,
"minLength": _validators.minLength,
"minProperties": _validators.minProperties,
"minimum": _validators.minimum,
"multipleOf": _validators.multipleOf,
"not": _validators.not_,
"oneOf": _validators.oneOf,
"pattern": _validators.pattern,
"patternProperties": _validators.patternProperties,
"prefixItems": _validators.prefixItems,
"properties": _validators.properties,
"propertyNames": _validators.propertyNames,
"required": _validators.required,
"type": _validators.type,
"unevaluatedItems": _validators.unevaluatedItems,
"unevaluatedProperties": _validators.unevaluatedProperties,
"uniqueItems": _validators.uniqueItems,
},
type_checker=_types.draft202012_type_checker,
format_checker=_format.draft202012_format_checker,
version="draft2020-12",
)
_LATEST_VERSION = Draft202012Validator
class RefResolver:
"""
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(_store_schema_list())
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.
"""
warnings.warn(
"jsonschema.RefResolver.in_scope is deprecated and will be "
"removed in a future release.",
DeprecationWarning,
stacklevel=3,
)
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 _find_in_referrer(self, key):
return self._get_subschemas_cache()[key]
@lru_cache() # noqa: B019
def _get_subschemas_cache(self):
cache = {key: [] for key in _SUBSCHEMAS_KEYWORDS}
for keyword, subschema in _search_schema(
self.referrer, _match_subschema_keywords,
):
cache[keyword].append(subschema)
return cache
@lru_cache() # noqa: B019
def _find_in_subschemas(self, url):
subschemas = self._get_subschemas_cache()["$id"]
if not subschemas:
return None
uri, fragment = urldefrag(url)
for subschema in subschemas:
target_uri = self._urljoin_cache(
self.resolution_scope, subschema["$id"],
)
if target_uri.rstrip("/") == uri.rstrip("/"):
if fragment:
subschema = self.resolve_fragment(subschema, fragment)
return url, subschema
return None
def resolve(self, ref):
"""
Resolve the given reference.
"""
url = self._urljoin_cache(self.resolution_scope, ref).rstrip("/")
match = self._find_in_subschemas(url)
if match is not None:
return match
return url, self._remote_cache(url)
def resolve_from_url(self, url):
"""
Resolve the given URL.
"""
url, fragment = urldefrag(url)
if url:
try:
document = self.store[url]
except KeyError:
try:
document = self.resolve_remote(url)
except Exception as exc:
raise exceptions.RefResolutionError(exc)
else:
document = self.referrer
return self.resolve_fragment(document, fragment)
def resolve_fragment(self, document, fragment):
"""
Resolve a ``fragment`` within the referenced ``document``.
Arguments:
document:
The referent document
fragment (str):
a URI fragment to resolve within it
"""
fragment = fragment.lstrip("/")
if not fragment:
return document
if document is self.referrer:
find = self._find_in_referrer
else:
def find(key):
yield from _search_schema(document, _match_keyword(key))
for keyword in ["$anchor", "$dynamicAnchor"]:
for subschema in find(keyword):
if fragment == subschema[keyword]:
return subschema
for keyword in ["id", "$id"]:
for subschema in find(keyword):
if "#" + fragment == subschema[keyword]:
return subschema
# Resolve via path
parts = unquote(fragment).split("/") if fragment else []
for part in parts:
part = part.replace("~1", "/").replace("~0", "~")
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(
f"Unresolvable JSON pointer: {fragment!r}",
)
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 ["http", "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
_SUBSCHEMAS_KEYWORDS = ("$id", "id", "$anchor", "$dynamicAnchor")
def _match_keyword(keyword):
def matcher(value):
if keyword in value:
yield value
return matcher
def _match_subschema_keywords(value):
for keyword in _SUBSCHEMAS_KEYWORDS:
if keyword in value:
yield keyword, value
def _search_schema(schema, matcher):
"""Breadth-first search routine."""
values = deque([schema])
while values:
value = values.pop()
if not isinstance(value, dict):
continue
yield from matcher(value)
values.extendleft(value.values())
def validate(instance, schema, cls=None, *args, **kwargs):
"""
Validate an instance under the given schema.
>>> validate([2, 3, 4], {"maxItems": 2})
Traceback (most recent call last):
...
ValidationError: [2, 3, 4] is too long
:func:`validate` will first verify that the provided schema is
itself valid, since not doing so can lead to less obvious error
messages and fail in less obvious or consistent ways.
If you know you have a valid schema already, especially if you
intend to validate multiple instances with the same schema, you
likely would prefer using the `Validator.validate` method directly
on a specific validator (e.g. ``Draft7Validator.validate``).
Arguments:
instance:
The instance to validate
schema:
The schema to validate with
cls (Validator):
The class that will be used to validate the instance.
If the ``cls`` argument is not provided, two things will happen
in accordance with the specification. First, if the schema has a
:kw:`$schema` keyword containing a known meta-schema [#]_ then the
proper validator will be used. The specification recommends that
all schemas contain :kw:`$schema` properties for this reason. If no
:kw:`$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=_UNSET):
"""
Retrieve the validator class appropriate for validating the given schema.
Uses the :kw:`$schema` keyword that should be present in the given
schema to look up the appropriate validator class.
Arguments:
schema (collections.abc.Mapping or bool):
the schema to look at
default:
the default to return if the appropriate validator class
cannot be determined.
If unprovided, the default is to return the latest supported
draft.
"""
DefaultValidator = _LATEST_VERSION if default is _UNSET else default
if schema is True or schema is False or "$schema" not in schema:
return DefaultValidator
if schema["$schema"] not in _META_SCHEMAS:
if default is _UNSET:
warn(
(
"The metaschema specified by $schema was not found. "
"Using the latest draft to validate, but this will raise "
"an error in the future."
),
DeprecationWarning,
stacklevel=2,
)
return _META_SCHEMAS.get(schema["$schema"], DefaultValidator)