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|
"""JSON schemas and associated utilities."""
from os import path
import json
from typing import Mapping
from pkg_resources import resource_string
import jsonschema
from stringcase import snakecase
class _LocalRefResolver(jsonschema.RefResolver):
"""Resolve package-local JSON schema id's."""
def __init__(self):
"""Initialize a new instance."""
jsonschema.RefResolver.__init__(self, "", "")
@staticmethod
def _ref_to_file(ref: str) -> str:
"""Translate a JSON schema ref to its corresponding file name.
>>> _LocalRefResolver._ref_to_file("/addressSchema")
'address_schema.json'
"""
_ref = ref.lstrip("/")
# handle weird special cases
_ref = _ref.replace("ECSignature", "EcSignature")
_ref = _ref.replace("Schema", "")
return f"{snakecase(_ref)}_schema.json"
def resolve_from_url(self, url: str) -> str:
"""Resolve the given URL.
:param url: a string representing the URL of the JSON schema to fetch.
:returns: a string representing the deserialized JSON schema
:raises jsonschema.ValidationError: when the resource associated with
`url` does not exist.
"""
ref = url.replace("file://", "")
return json.loads(
resource_string(
"zero_ex.json_schemas",
f"schemas/{_LocalRefResolver._ref_to_file(ref)}",
)
)
# Instantiate the `_LocalRefResolver()` only once so that `assert_valid()` can
# perform multiple schema validations without reading from disk the schema
# every time.
_LOCAL_RESOLVER = _LocalRefResolver()
def assert_valid(data: Mapping, schema_id: str) -> None:
"""Validate the given `data` against the specified `schema`.
:param data: Python dictionary to be validated as a JSON object.
:param schema_id: id property of the JSON schema to validate against. Must
be one of those listed in `the 0x JSON schema files
<https://github.com/0xProject/0x-monorepo/tree/development/packages/json-schemas/schemas>`_.
Raises an exception if validation fails.
>>> assert_valid(
... {'v': 27, 'r': '0x'+'f'*64, 's': '0x'+'f'*64},
... '/ECSignature',
... )
"""
# noqa
_, schema = _LOCAL_RESOLVER.resolve(schema_id)
jsonschema.validate(data, schema, resolver=_LOCAL_RESOLVER)
|
