Source code for prance

"""
Prance implements parsers for Swagger/OpenAPI 2.0 and 3.0.0 API specs.

See https://openapis.org/ for details on the specification.

Included is a BaseParser that reads and validates swagger specs, and a
ResolvingParser that additionally resolves any $ref references.
"""

__author__ = "Jens Finkhaeuser"
__copyright__ = "Copyright (c) 2016-2021 Jens Finkhaeuser"
__license__ = "MIT"
__all__ = ("util", "mixins", "cli", "convert")

try:
    from prance._version import version as __version__
except ImportError:
    # todo: better gussing
    __version__ = "0.20.0+unknown"


# Define our own error class
[docs]class ValidationError(Exception): pass
from . import mixins # Placeholder for when no URL is specified for the main spec file import sys if sys.platform == "win32": # pragma: nocover # Placeholder must be absolute _PLACEHOLDER_URL = "file:///c:/__placeholder_url__.yaml" else: _PLACEHOLDER_URL = "file:///__placeholder_url__.yaml"
[docs]class BaseParser(mixins.YAMLMixin, mixins.JSONMixin): """ The BaseParser loads, parses and validates OpenAPI 2.0 and 3.0.0 specs. Uses :py:class:`YAMLMixin` and :py:class:`JSONMixin` for additional functionality. """ BACKENDS = { "flex": ((2,), "_validate_flex"), "swagger-spec-validator": ((2,), "_validate_swagger_spec_validator"), "openapi-spec-validator": ((2, 3), "_validate_openapi_spec_validator"), } SPEC_VERSION_2_PREFIX = "Swagger/OpenAPI" SPEC_VERSION_3_PREFIX = "OpenAPI" def __init__(self, url=None, spec_string=None, lazy=False, **kwargs): """ Load, parse and validate specs. You can either provide a URL or a spec string, but not both. :param str url: The URL of the file to load. URLs missing a scheme are assumed to be file URLs. :param str spec_string: The specifications to parse. :param bool lazy: If true, do not load or parse anything. Instead wait for the parse function to be invoked. :param str backend: [optional] one of 'flex', 'swagger-spec-validator' or 'openapi-spec-validator'. Determines the validation backend to use. Defaults to the first installed backend in the ordered list obtained from util.validation_backends(). :param bool strict: [optional] Applies only to the 'swagger-spec-validator' backend. If False, accepts non-String keys by stringifying them before validation. Defaults to True. :param str encoding: [optional] For local URLs, use the given file encoding instead of auto-detecting. Defaults to None. """ assert url or spec_string and not (url and spec_string), ( "You must provide either a URL to read, or a spec string to " "parse, but not both!" ) # Keep the parameters around for later use self.url = None if url: from .util.url import absurl from .util.fs import abspath import os self.url = absurl(url, abspath(os.getcwd())) else: self.url = _PLACEHOLDER_URL self._spec_string = spec_string # Initialize variables we're filling later self.specification = None self.version = None self.version_name = None self.version_parsed = () self.valid = False # Add kw args as options self.options = kwargs # Verify backend from .util import default_validation_backend self.backend = self.options.get("backend", default_validation_backend()) if self.backend not in BaseParser.BACKENDS.keys(): raise ValueError( f"Backend may only be one of {BaseParser.BACKENDS.keys()}!" ) # Start parsing if lazy mode is not requested. if not lazy: self.parse()
[docs] def parse(self): # noqa: F811 """ When the BaseParser was lazily created, load and parse now. You can use this function to re-use an existing parser for parsing multiple files by setting its url property and then invoking this function. """ strict = self.options.get("strict", True) # If we have a file name, we need to read that in. if self.url and self.url != _PLACEHOLDER_URL: from .util.url import fetch_url encoding = self.options.get("encoding", None) self.specification = fetch_url(self.url, encoding=encoding, strict=strict) # If we have a spec string, try to parse it. if self._spec_string: from .util.formats import parse_spec self.specification = parse_spec(self._spec_string, self.url) # If we have a parsed spec, convert it to JSON. Then we can validate # the JSON. At this point, we *require* a parsed specification to exist, # so we might as well assert. assert self.specification, "No specification parsed, cannot validate!" self._validate()
def _validate(self): # Ensure specification is a mapping from collections.abc import Mapping if not isinstance(self.specification, Mapping): raise ValidationError("Could not parse specifications!") # Ensure the selected backend supports the given spec version versions, validator_name = BaseParser.BACKENDS[self.backend] # Fetch the spec version. Note that this is the spec version the spec # *claims* to be; we later set the one we actually could validate as. spec_version = None if spec_version is None: spec_version = self.specification.get("openapi", None) if spec_version is None: spec_version = self.specification.get("swagger", None) if spec_version is None: raise ValidationError( "Could not determine specification schema " "version!" ) # Try parsing the spec version, examine the first component. import distutils.version parsed = distutils.version.StrictVersion(spec_version).version if parsed[0] not in versions: raise ValidationError( 'Version mismatch: selected backend "%s"' " does not support specified version %s!" % (self.backend, spec_version) ) # Validate the parsed specs, using the given validation backend. validator = getattr(self, validator_name) # Set valid flag according to whether validator succeeds self.valid = False validator(parsed) self.valid = True def __set_version(self, prefix, version): self.version_name = prefix self.version_parsed = version import semver self.semver = str(semver.VersionInfo(*version)) stringified = self.semver if prefix == BaseParser.SPEC_VERSION_2_PREFIX: stringified = "%d.%d" % (version[0], version[1]) self.version = f"{self.version_name} {stringified}" def _validate_flex(self, spec_version): # pragma: nocover # Set the version independently of whether validation succeeds self.__set_version(BaseParser.SPEC_VERSION_2_PREFIX, spec_version) from flex.exceptions import ValidationError as JSEValidationError from flex.core import parse as validate try: validate(self.specification) except JSEValidationError as ex: from .util.exceptions import raise_from raise_from(ValidationError, ex) def _validate_swagger_spec_validator(self, spec_version): # pragma: nocover # Set the version independently of whether validation succeeds self.__set_version(BaseParser.SPEC_VERSION_2_PREFIX, spec_version) from swagger_spec_validator.common import SwaggerValidationError as SSVErr from swagger_spec_validator.validator20 import validate_spec try: validate_spec(self.specification) except SSVErr as ex: from .util.exceptions import raise_from raise_from(ValidationError, ex) def _validate_openapi_spec_validator(self, spec_version): # pragma: nocover from openapi_spec_validator import validate_v2_spec, validate_v3_spec from jsonschema.exceptions import ValidationError as JSEValidationError from jsonschema.exceptions import RefResolutionError # Validate according to detected version. Unsupported versions are # already caught outside of this function. from .util.exceptions import raise_from if spec_version[0] == 3: # Set the version independently of whether validation succeeds self.__set_version(BaseParser.SPEC_VERSION_3_PREFIX, spec_version) try: validate_v3_spec(self.specification) except TypeError as type_ex: raise_from(ValidationError, type_ex, self._strict_warning()) except JSEValidationError as v3_ex: raise_from(ValidationError, v3_ex) except RefResolutionError as ref_ex: raise_from(ValidationError, ref_ex) elif spec_version[0] == 2: # Set the version independently of whether validation succeeds self.__set_version(BaseParser.SPEC_VERSION_2_PREFIX, spec_version) try: validate_v2_spec(self.specification) except TypeError as type_ex: # pragma: nocover raise_from(ValidationError, type_ex, self._strict_warning()) except JSEValidationError as v2_ex: raise_from(ValidationError, v2_ex) except RefResolutionError as ref_ex: raise_from(ValidationError, ref_ex) def _strict_warning(self): """Return a warning if strict mode is off.""" if self.options.get("strict", True): return ( "Strict mode enabled (the default), so this could be due to an " "integer key, such as an HTTP status code." ) return ( "Strict mode disabled. Prance cannot help you narrow this further " "down, sorry." )
[docs]class ResolvingParser(BaseParser): """The ResolvingParser extends BaseParser with resolving references by inlining.""" def __init__(self, url=None, spec_string=None, lazy=False, **kwargs): """ See :py:class:`BaseParser`. Resolves JSON pointers/references (i.e. '$ref' keys) before validating the specs. The implication is that self.specfication is fully resolved, and does not contain any references. Additional parameters, see :py::class:`util.RefResolver`. """ # Create a reference cache self.__reference_cache = {} BaseParser.__init__(self, url=url, spec_string=spec_string, lazy=lazy, **kwargs) def _validate(self): # We have a problem with the BaseParser's validate function: the # jsonschema implementation underlying it does not accept relative # path references, but the Swagger specs allow them: # http://swagger.io/specification/#referenceObject # We therefore use our own resolver first, and validate later. from .util.resolver import RefResolver forward_arg_names = ( "encoding", "recursion_limit", "recursion_limit_handler", "resolve_types", "resolve_method", "strict", ) forward_args = { k: v for (k, v) in self.options.items() if k in forward_arg_names } resolver = RefResolver( self.specification, self.url, reference_cache=self.__reference_cache, **forward_args, ) resolver.resolve_references() self.specification = resolver.specs # Now validate - the BaseParser knows the specifics BaseParser._validate(self)
# Underscored to allow some time for the public API to be stabilized. class _TranslatingParser(BaseParser): def _validate(self): from .util.translator import _RefTranslator translator = _RefTranslator(self.specification, self.url) translator.translate_references() self.specification = translator.specs BaseParser._validate(self)