794 lines
24 KiB
Python
794 lines
24 KiB
Python
"""
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An implementation of JSON Schema for Python
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The main functionality is provided by the validator classes for each of the
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supported JSON Schema versions.
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Most commonly, :func:`validate` is the quickest way to simply validate a given
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instance under a schema, and will create a validator for you.
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"""
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from __future__ import division, unicode_literals
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import collections
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import json
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import itertools
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import operator
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import re
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import sys
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__version__ = "0.8.0"
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PY3 = sys.version_info[0] >= 3
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if PY3:
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from urllib import parse as urlparse
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from urllib.parse import unquote
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from urllib.request import urlopen
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basestring = unicode = str
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iteritems = operator.methodcaller("items")
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else:
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from itertools import izip as zip
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from urllib import unquote
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from urllib2 import urlopen
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import urlparse
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iteritems = operator.methodcaller("iteritems")
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FLOAT_TOLERANCE = 10 ** -15
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validators = {}
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def validates(version):
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"""
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Register the decorated validator for a ``version`` of the specification.
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Registered validators and their meta schemas will be considered when
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parsing ``$schema`` properties' URIs.
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:argument str version: an identifier to use as the version's name
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:returns: a class decorator to decorate the validator with the version
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"""
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def _validates(cls):
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validators[version] = cls
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return cls
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return _validates
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class UnknownType(Exception):
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"""
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An attempt was made to check if an instance was of an unknown type.
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"""
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class RefResolutionError(Exception):
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"""
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A JSON reference failed to resolve.
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"""
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class SchemaError(Exception):
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"""
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The provided schema is malformed.
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The same attributes are present as for :exc:`ValidationError`\s.
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"""
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def __init__(self, message, validator=None, path=()):
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super(SchemaError, self).__init__(message, validator, path)
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self.message = message
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self.path = list(path)
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self.validator = validator
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def __str__(self):
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return self.message
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class ValidationError(Exception):
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"""
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The instance didn't properly validate under the provided schema.
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Relevant attributes are:
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* ``message`` : a human readable message explaining the error
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* ``path`` : a list containing the path to the offending element (or []
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if the error happened globally) in *reverse* order (i.e.
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deepest index first).
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"""
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def __init__(self, message, validator=None, path=()):
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# Any validator that recurses (e.g. properties and items) must append
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# to the ValidationError's path to properly maintain where in the
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# instance the error occurred
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super(ValidationError, self).__init__(message, validator, path)
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self.message = message
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self.path = list(path)
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self.validator = validator
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def __str__(self):
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return self.message
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@validates("draft3")
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class Draft3Validator(object):
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"""
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A validator for JSON Schema draft 3.
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"""
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DEFAULT_TYPES = {
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"array" : list, "boolean" : bool, "integer" : int, "null" : type(None),
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"number" : (int, float), "object" : dict, "string" : basestring,
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}
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def __init__(self, schema, types=(), resolver=None):
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self._types = dict(self.DEFAULT_TYPES)
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self._types.update(types)
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if resolver is None:
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resolver = RefResolver.from_schema(schema)
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self.resolver = resolver
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self.schema = schema
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def is_type(self, instance, type):
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if type == "any":
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return True
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elif type not in self._types:
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raise UnknownType(type)
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type = self._types[type]
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# bool inherits from int, so ensure bools aren't reported as integers
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if isinstance(instance, bool):
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type = _flatten(type)
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if int in type and bool not in type:
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return False
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return isinstance(instance, type)
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def is_valid(self, instance, _schema=None):
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error = next(self.iter_errors(instance, _schema), None)
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return error is None
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@classmethod
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def check_schema(cls, schema):
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for error in cls(cls.META_SCHEMA).iter_errors(schema):
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raise SchemaError(
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error.message, validator=error.validator, path=error.path,
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)
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def iter_errors(self, instance, _schema=None):
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if _schema is None:
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_schema = self.schema
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for k, v in iteritems(_schema):
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validator = getattr(self, "validate_%s" % (k.lstrip("$"),), None)
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if validator is None:
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continue
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errors = validator(v, instance, _schema) or ()
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for error in errors:
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# set the validator if it wasn't already set by the called fn
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if error.validator is None:
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error.validator = k
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yield error
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def validate(self, *args, **kwargs):
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for error in self.iter_errors(*args, **kwargs):
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raise error
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def validate_type(self, types, instance, schema):
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types = _list(types)
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for type in types:
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if self.is_type(type, "object"):
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if self.is_valid(instance, type):
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break
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elif self.is_type(type, "string"):
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if self.is_type(instance, type):
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break
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else:
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yield ValidationError(_types_msg(instance, types))
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return
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def validate_properties(self, properties, instance, schema):
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if not self.is_type(instance, "object"):
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return
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for property, subschema in iteritems(properties):
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if property in instance:
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for error in self.iter_errors(instance[property], subschema):
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error.path.append(property)
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yield error
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elif subschema.get("required", False):
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yield ValidationError(
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"%r is a required property" % (property,),
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validator="required",
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path=[property],
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)
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def validate_patternProperties(self, patternProperties, instance, schema):
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if not self.is_type(instance, "object"):
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return
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for pattern, subschema in iteritems(patternProperties):
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for k, v in iteritems(instance):
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if re.match(pattern, k):
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for error in self.iter_errors(v, subschema):
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yield error
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def validate_additionalProperties(self, aP, instance, schema):
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if not self.is_type(instance, "object"):
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return
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extras = set(_find_additional_properties(instance, schema))
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if self.is_type(aP, "object"):
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for extra in extras:
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for error in self.iter_errors(instance[extra], aP):
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yield error
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elif not aP and extras:
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error = "Additional properties are not allowed (%s %s unexpected)"
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yield ValidationError(error % _extras_msg(extras))
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def validate_dependencies(self, dependencies, instance, schema):
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if not self.is_type(instance, "object"):
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return
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for property, dependency in iteritems(dependencies):
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if property not in instance:
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continue
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if self.is_type(dependency, "object"):
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for error in self.iter_errors(instance, dependency):
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yield error
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else:
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dependencies = _list(dependency)
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for dependency in dependencies:
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if dependency not in instance:
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yield ValidationError(
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"%r is a dependency of %r" % (dependency, property)
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)
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def validate_items(self, items, instance, schema):
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if not self.is_type(instance, "array"):
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return
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if self.is_type(items, "object"):
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for index, item in enumerate(instance):
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for error in self.iter_errors(item, items):
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error.path.append(index)
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yield error
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else:
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for (index, item), subschema in zip(enumerate(instance), items):
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for error in self.iter_errors(item, subschema):
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error.path.append(index)
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yield error
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def validate_additionalItems(self, aI, instance, schema):
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if (
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not self.is_type(instance, "array") or
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not self.is_type(schema.get("items"), "array")
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):
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return
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if self.is_type(aI, "object"):
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for item in instance[len(schema):]:
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for error in self.iter_errors(item, aI):
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yield error
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elif not aI and len(instance) > len(schema.get("items", [])):
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error = "Additional items are not allowed (%s %s unexpected)"
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yield ValidationError(
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error % _extras_msg(instance[len(schema.get("items", [])):])
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)
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def validate_minimum(self, minimum, instance, schema):
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if not self.is_type(instance, "number"):
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return
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instance = float(instance)
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if schema.get("exclusiveMinimum", False):
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failed = instance <= minimum
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cmp = "less than or equal to"
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else:
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failed = instance < minimum
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cmp = "less than"
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if failed:
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yield ValidationError(
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"%r is %s the minimum of %r" % (instance, cmp, minimum)
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)
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def validate_maximum(self, maximum, instance, schema):
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if not self.is_type(instance, "number"):
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return
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instance = float(instance)
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if schema.get("exclusiveMaximum", False):
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failed = instance >= maximum
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cmp = "greater than or equal to"
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else:
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failed = instance > maximum
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cmp = "greater than"
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if failed:
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yield ValidationError(
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"%r is %s the maximum of %r" % (instance, cmp, maximum)
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)
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def validate_minItems(self, mI, instance, schema):
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if self.is_type(instance, "array") and len(instance) < mI:
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yield ValidationError("%r is too short" % (instance,))
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def validate_maxItems(self, mI, instance, schema):
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if self.is_type(instance, "array") and len(instance) > mI:
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yield ValidationError("%r is too long" % (instance,))
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def validate_uniqueItems(self, uI, instance, schema):
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if uI and self.is_type(instance, "array") and not _uniq(instance):
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yield ValidationError("%r has non-unique elements" % instance)
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def validate_pattern(self, patrn, instance, schema):
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if self.is_type(instance, "string") and not re.match(patrn, instance):
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yield ValidationError("%r does not match %r" % (instance, patrn))
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def validate_minLength(self, mL, instance, schema):
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if self.is_type(instance, "string") and len(instance) < mL:
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yield ValidationError("%r is too short" % (instance,))
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def validate_maxLength(self, mL, instance, schema):
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if self.is_type(instance, "string") and len(instance) > mL:
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yield ValidationError("%r is too long" % (instance,))
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def validate_enum(self, enums, instance, schema):
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if instance not in enums:
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yield ValidationError("%r is not one of %r" % (instance, enums))
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def validate_divisibleBy(self, dB, instance, schema):
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if not self.is_type(instance, "number"):
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return
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if isinstance(dB, float):
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mod = instance % dB
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failed = (mod > FLOAT_TOLERANCE) and (dB - mod) > FLOAT_TOLERANCE
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else:
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failed = instance % dB
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if failed:
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yield ValidationError("%r is not divisible by %r" % (instance, dB))
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def validate_disallow(self, disallow, instance, schema):
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for disallowed in _list(disallow):
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if self.is_valid(instance, {"type" : [disallowed]}):
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yield ValidationError(
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"%r is disallowed for %r" % (disallowed, instance)
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)
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def validate_extends(self, extends, instance, schema):
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if self.is_type(extends, "object"):
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extends = [extends]
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for subschema in extends:
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for error in self.iter_errors(instance, subschema):
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yield error
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def validate_ref(self, ref, instance, schema):
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resolved = self.resolver.resolve(ref)
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for error in self.iter_errors(instance, resolved):
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yield error
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Draft3Validator.META_SCHEMA = {
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"$schema" : "http://json-schema.org/draft-03/schema#",
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"id" : "http://json-schema.org/draft-03/schema#",
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"type" : "object",
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"properties" : {
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"type" : {
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"type" : ["string", "array"],
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"items" : {"type" : ["string", {"$ref" : "#"}]},
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"uniqueItems" : True,
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"default" : "any"
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},
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"properties" : {
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"type" : "object",
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"additionalProperties" : {"$ref" : "#", "type": "object"},
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"default" : {}
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},
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"patternProperties" : {
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"type" : "object",
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"additionalProperties" : {"$ref" : "#"},
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"default" : {}
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},
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"additionalProperties" : {
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"type" : [{"$ref" : "#"}, "boolean"], "default" : {}
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},
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"items" : {
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"type" : [{"$ref" : "#"}, "array"],
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"items" : {"$ref" : "#"},
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"default" : {}
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},
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"additionalItems" : {
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"type" : [{"$ref" : "#"}, "boolean"], "default" : {}
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},
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"required" : {"type" : "boolean", "default" : False},
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"dependencies" : {
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"type" : ["string", "array", "object"],
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"additionalProperties" : {
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"type" : ["string", "array", {"$ref" : "#"}],
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"items" : {"type" : "string"}
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},
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"default" : {}
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},
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"minimum" : {"type" : "number"},
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"maximum" : {"type" : "number"},
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"exclusiveMinimum" : {"type" : "boolean", "default" : False},
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"exclusiveMaximum" : {"type" : "boolean", "default" : False},
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"minItems" : {"type" : "integer", "minimum" : 0, "default" : 0},
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"maxItems" : {"type" : "integer", "minimum" : 0},
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"uniqueItems" : {"type" : "boolean", "default" : False},
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"pattern" : {"type" : "string", "format" : "regex"},
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"minLength" : {"type" : "integer", "minimum" : 0, "default" : 0},
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"maxLength" : {"type" : "integer"},
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"enum" : {"type" : "array", "minItems" : 1, "uniqueItems" : True},
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"default" : {"type" : "any"},
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"title" : {"type" : "string"},
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"description" : {"type" : "string"},
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"format" : {"type" : "string"},
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"maxDecimal" : {"type" : "number", "minimum" : 0},
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"divisibleBy" : {
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"type" : "number",
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"minimum" : 0,
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"exclusiveMinimum" : True,
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"default" : 1
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},
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"disallow" : {
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"type" : ["string", "array"],
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"items" : {"type" : ["string", {"$ref" : "#"}]},
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"uniqueItems" : True
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},
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"extends" : {
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"type" : [{"$ref" : "#"}, "array"],
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"items" : {"$ref" : "#"},
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"default" : {}
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},
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"id" : {"type" : "string", "format" : "uri"},
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"$ref" : {"type" : "string", "format" : "uri"},
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"$schema" : {"type" : "string", "format" : "uri"},
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},
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"dependencies" : {
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"exclusiveMinimum" : "minimum", "exclusiveMaximum" : "maximum"
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},
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}
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class RefResolver(object):
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"""
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Resolve JSON References.
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:argument str base_uri: URI of the referring document
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:argument referrer: the actual referring document
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:argument dict store: a mapping from URIs to documents to cache
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"""
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def __init__(self, base_uri, referrer, store=()):
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self.base_uri = base_uri
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self.referrer = referrer
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self.store = dict(store, **_meta_schemas())
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@classmethod
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def from_schema(cls, schema, *args, **kwargs):
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"""
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Construct a resolver from a JSON schema object.
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:argument schema schema: the referring schema
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:rtype: :class:`RefResolver`
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"""
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return cls(schema.get("id", ""), schema, *args, **kwargs)
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def resolve(self, ref):
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"""
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Resolve a JSON ``ref``.
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:argument str ref: reference to resolve
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:returns: the referrant document
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"""
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base_uri = self.base_uri
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uri, fragment = urlparse.urldefrag(urlparse.urljoin(base_uri, ref))
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if uri in self.store:
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document = self.store[uri]
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elif not uri or uri == self.base_uri:
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document = self.referrer
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else:
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document = self.resolve_remote(uri)
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return self.resolve_fragment(document, fragment.lstrip("/"))
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def resolve_fragment(self, document, fragment):
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"""
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Resolve a ``fragment`` within the referenced ``document``.
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:argument document: the referrant document
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:argument str fragment: a URI fragment to resolve within it
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"""
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parts = unquote(fragment).split("/") if fragment else []
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for part in parts:
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part = part.replace("~1", "/").replace("~0", "~")
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if part not in document:
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raise RefResolutionError(
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"Unresolvable JSON pointer: %r" % fragment
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)
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document = document[part]
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return document
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def resolve_remote(self, uri):
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"""
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Resolve a remote ``uri``.
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Does not check the store first.
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:argument str uri: the URI to resolve
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:returns: the retrieved document
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"""
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return json.load(urlopen(uri))
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class ErrorTree(object):
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"""
|
|
ErrorTrees make it easier to check which validations failed.
|
|
|
|
"""
|
|
|
|
def __init__(self, errors=()):
|
|
self.errors = {}
|
|
self._contents = collections.defaultdict(self.__class__)
|
|
|
|
for error in errors:
|
|
container = self
|
|
for element in reversed(error.path):
|
|
container = container[element]
|
|
container.errors[error.validator] = error
|
|
|
|
def __contains__(self, k):
|
|
return k in self._contents
|
|
|
|
def __getitem__(self, k):
|
|
"""
|
|
Retrieve the child tree with key ``k``.
|
|
|
|
"""
|
|
|
|
return self._contents[k]
|
|
|
|
def __setitem__(self, k, v):
|
|
self._contents[k] = v
|
|
|
|
def __iter__(self):
|
|
return iter(self._contents)
|
|
|
|
def __len__(self):
|
|
return self.total_errors
|
|
|
|
def __repr__(self):
|
|
return "<%s (%s total errors)>" % (self.__class__.__name__, len(self))
|
|
|
|
@property
|
|
def total_errors(self):
|
|
"""
|
|
The total number of errors in the entire tree, including children.
|
|
|
|
"""
|
|
|
|
child_errors = sum(len(tree) for _, tree in iteritems(self._contents))
|
|
return len(self.errors) + child_errors
|
|
|
|
|
|
def _meta_schemas():
|
|
"""
|
|
Collect the urls and meta schemas from each known validator.
|
|
|
|
"""
|
|
|
|
meta_schemas = (v.META_SCHEMA for v in validators.values())
|
|
return dict((urlparse.urldefrag(m["id"])[0], m) for m in meta_schemas)
|
|
|
|
|
|
def _find_additional_properties(instance, schema):
|
|
"""
|
|
Return the set of additional properties for the given ``instance``.
|
|
|
|
Weeds out properties that should have been validated by ``properties`` and
|
|
/ or ``patternProperties``.
|
|
|
|
Assumes ``instance`` is dict-like already.
|
|
|
|
"""
|
|
|
|
properties = schema.get("properties", {})
|
|
patterns = "|".join(schema.get("patternProperties", {}))
|
|
for property in instance:
|
|
if property not in properties:
|
|
if patterns and re.search(patterns, property):
|
|
continue
|
|
yield property
|
|
|
|
|
|
def _extras_msg(extras):
|
|
"""
|
|
Create an error message for extra items or properties.
|
|
|
|
"""
|
|
|
|
if len(extras) == 1:
|
|
verb = "was"
|
|
else:
|
|
verb = "were"
|
|
return ", ".join(repr(extra) for extra in extras), verb
|
|
|
|
|
|
def _types_msg(instance, types):
|
|
"""
|
|
Create an error message for a failure to match the given types.
|
|
|
|
If the ``instance`` is an object and contains a ``name`` property, it will
|
|
be considered to be a description of that object and used as its type.
|
|
|
|
Otherwise the message is simply the reprs of the given ``types``.
|
|
|
|
"""
|
|
|
|
reprs = []
|
|
for type in types:
|
|
try:
|
|
reprs.append(repr(type["name"]))
|
|
except Exception:
|
|
reprs.append(repr(type))
|
|
return "%r is not of type %s" % (instance, ", ".join(reprs))
|
|
|
|
|
|
def _flatten(suitable_for_isinstance):
|
|
"""
|
|
isinstance() can accept a bunch of really annoying different types:
|
|
* a single type
|
|
* a tuple of types
|
|
* an arbitrary nested tree of tuples
|
|
|
|
Return a flattened tuple of the given argument.
|
|
|
|
"""
|
|
|
|
types = set()
|
|
|
|
if not isinstance(suitable_for_isinstance, tuple):
|
|
suitable_for_isinstance = (suitable_for_isinstance,)
|
|
for thing in suitable_for_isinstance:
|
|
if isinstance(thing, tuple):
|
|
types.update(_flatten(thing))
|
|
else:
|
|
types.add(thing)
|
|
return tuple(types)
|
|
|
|
|
|
def _list(thing):
|
|
"""
|
|
Wrap ``thing`` in a list if it's a single str.
|
|
|
|
Otherwise, return it unchanged.
|
|
|
|
"""
|
|
|
|
if isinstance(thing, basestring):
|
|
return [thing]
|
|
return thing
|
|
|
|
|
|
def _delist(thing):
|
|
"""
|
|
Unwrap ``thing`` to a single element if its a single str in a list.
|
|
|
|
Otherwise, return it unchanged.
|
|
|
|
"""
|
|
|
|
if (
|
|
isinstance(thing, list) and
|
|
len(thing) == 1
|
|
and isinstance(thing[0], basestring)
|
|
):
|
|
return thing[0]
|
|
return thing
|
|
|
|
|
|
def _unbool(element, true=object(), false=object()):
|
|
"""
|
|
A hack to make True and 1 and False and 0 unique for _uniq.
|
|
|
|
"""
|
|
|
|
if element is True:
|
|
return true
|
|
elif element is False:
|
|
return false
|
|
return element
|
|
|
|
|
|
def _uniq(container):
|
|
"""
|
|
Check if all of a container's elements are unique.
|
|
|
|
Successively tries first to rely that the elements are hashable, then
|
|
falls back on them being sortable, and finally falls back on brute
|
|
force.
|
|
|
|
"""
|
|
|
|
try:
|
|
return len(set(_unbool(i) for i in container)) == len(container)
|
|
except TypeError:
|
|
try:
|
|
sort = sorted(_unbool(i) for i in container)
|
|
sliced = itertools.islice(sort, 1, None)
|
|
for i, j in zip(sort, sliced):
|
|
if i == j:
|
|
return False
|
|
except (NotImplementedError, TypeError):
|
|
seen = []
|
|
for e in container:
|
|
e = _unbool(e)
|
|
if e in seen:
|
|
return False
|
|
seen.append(e)
|
|
return True
|
|
|
|
|
|
def validate(instance, schema, cls=Draft3Validator, *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 or don't care, you might prefer using the ``validate`` method
|
|
directly on a specific validator (e.g. :meth:`Draft3Validator.validate`).
|
|
|
|
``cls`` is a validator class that will be used to validate the instance.
|
|
By default this is a draft 3 validator. Any other provided positional and
|
|
keyword arguments will be provided to this class when constructing a
|
|
validator.
|
|
|
|
:raises:
|
|
:exc:`ValidationError` if the instance is invalid
|
|
|
|
:exc:`SchemaError` if the schema itself is invalid
|
|
|
|
"""
|
|
|
|
|
|
cls.check_schema(schema)
|
|
cls(schema, *args, **kwargs).validate(instance)
|