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from __future__ import absolute_import
from collections import Callable, Hashable, Iterable, Mapping, MutableMapping
from copy import copy
from cerberus import errors
from cerberus.platform import _str_type
from cerberus.utils import get_Validator_class, validator_factory, mapping_hash
class SchemaError(Exception):
""" Raised when the validation schema is missing, has the wrong format or
contains errors. """
pass
class DefinitionSchema(MutableMapping):
""" A dict-subclass for caching of validated schemas. """
def __new__(cls, *args, **kwargs):
if 'SchemaValidator' not in globals():
global SchemaValidator
SchemaValidator = validator_factory('SchemaValidator',
SchemaValidatorMixin)
return super(DefinitionSchema, cls).__new__(cls)
def __init__(self, validator, schema={}):
"""
:param validator: An instance of Validator-(sub-)class that uses this
schema.
:param schema: A definition-schema as ``dict``. Defaults to an empty
one.
"""
if not isinstance(validator, get_Validator_class()):
raise RuntimeError('validator argument must be a Validator-'
'instance.')
self.validator = validator
if isinstance(schema, _str_type):
schema = validator.schema_registry.get(schema, schema)
if not isinstance(schema, Mapping):
try:
schema = dict(schema)
except Exception:
raise SchemaError(
errors.SCHEMA_ERROR_DEFINITION_TYPE.format(schema))
self.validation_schema = SchemaValidationSchema(validator)
self.schema_validator = SchemaValidator(
None, allow_unknown=self.validation_schema,
error_handler=errors.SchemaErrorHandler,
target_schema=schema, target_validator=validator)
schema = self.expand(schema)
self.validate(schema)
self.schema = schema
def __delitem__(self, key):
_new_schema = self.schema.copy()
try:
del _new_schema[key]
except ValueError:
raise SchemaError("Schema has no field '%s' defined" % key)
except Exception as e:
raise e
else:
del self.schema[key]
def __getitem__(self, item):
return self.schema[item]
def __iter__(self):
return iter(self.schema)
def __len__(self):
return len(self.schema)
def __repr__(self):
return str(self)
def __setitem__(self, key, value):
value = self.expand({0: value})[0]
self.validate({key: value})
self.schema[key] = value
def __str__(self):
return str(self.schema)
def copy(self):
return self.__class__(self.validator, self.schema.copy())
@classmethod
def expand(cls, schema):
try:
schema = cls._expand_logical_shortcuts(schema)
schema = cls._expand_subschemas(schema)
except Exception:
pass
return schema
@classmethod
def _expand_logical_shortcuts(cls, schema):
""" Expand agglutinated rules in a definition-schema.
:param schema: The schema-definition to expand.
:return: The expanded schema-definition.
"""
def is_of_rule(x):
return isinstance(x, _str_type) and \
x.startswith(('allof_', 'anyof_', 'noneof_', 'oneof_'))
for field in schema:
for of_rule in (x for x in schema[field] if is_of_rule(x)):
operator, rule = of_rule.split('_')
schema[field].update({operator: []})
for value in schema[field][of_rule]:
schema[field][operator].append({rule: value})
del schema[field][of_rule]
return schema
@classmethod
def _expand_subschemas(cls, schema):
def has_schema_rule():
return isinstance(schema[field], Mapping) and \
'schema' in schema[field]
def has_mapping_schema():
""" Tries to determine heuristically if the schema-constraints are
aimed to mappings. """
try:
return all(isinstance(x, Mapping) for x
in schema[field]['schema'].values())
except TypeError:
return False
for field in schema:
if not has_schema_rule():
pass
elif has_mapping_schema():
schema[field]['schema'] = cls.expand(schema[field]['schema'])
else: # assumes schema-constraints for a sequence
schema[field]['schema'] = \
cls.expand({0: schema[field]['schema']})[0]
for rule in ('keyschema', 'valueschema'):
if rule in schema[field]:
schema[field][rule] = \
cls.expand({0: schema[field][rule]})[0]
for rule in ('allof', 'anyof', 'items', 'noneof', 'oneof'):
if rule in schema[field]:
new_rules_definition = []
for item in schema[field][rule]:
new_rules_definition.append(cls.expand({0: item})[0])
schema[field][rule] = new_rules_definition
return schema
def update(self, schema):
try:
schema = self.expand(schema)
_new_schema = self.schema.copy()
_new_schema.update(schema)
self.validate(_new_schema)
except ValueError:
raise SchemaError(errors.SCHEMA_ERROR_DEFINITION_TYPE
.format(schema))
except Exception as e:
raise e
else:
self.schema = _new_schema
def regenerate_validation_schema(self):
self.validation_schema = SchemaValidationSchema(self.validator)
def validate(self, schema=None):
if schema is None:
schema = self.schema
_hash = mapping_hash(schema)
if _hash not in self.validator._valid_schemas:
self._validate(schema)
self.validator._valid_schemas.add(_hash)
def _validate(self, schema):
""" Validates a schema that defines rules against supported rules.
:param schema: The schema to be validated as a legal cerberus schema
according to the rules of this Validator object.
"""
if isinstance(schema, _str_type):
schema = self.validator.schema_registry.get(schema, schema)
if schema is None:
raise SchemaError(errors.SCHEMA_ERROR_MISSING)
schema = copy(schema)
for field in schema:
if isinstance(schema[field], _str_type):
schema[field] = rules_set_registry.get(schema[field],
schema[field])
if not self.schema_validator(schema, normalize=False):
raise SchemaError(self.schema_validator.errors)
class UnvalidatedSchema(DefinitionSchema):
def __init__(self, schema={}):
if not isinstance(schema, Mapping):
schema = dict(schema)
self.schema = schema
def validate(self, schema):
pass
class SchemaValidationSchema(UnvalidatedSchema):
def __init__(self, validator):
self.schema = {'allow_unknown': False,
'schema': validator.rules,
'type': 'dict'}
class SchemaValidatorMixin(object):
""" This validator is extended to validate schemas passed to a Cerberus
validator. """
@property
def known_rules_set_refs(self):
return self._config.get('known_rules_set_refs', ())
@known_rules_set_refs.setter
def known_rules_set_refs(self, value):
self._config['known_rules_set_refs'] = value
@property
def known_schema_refs(self):
return self._config.get('known_schema_refs', ())
@known_schema_refs.setter
def known_schema_refs(self, value):
self._config['known_schema_refs'] = value
@property
def target_schema(self):
""" The schema that is being validated. """
return self._config['target_schema']
@property
def target_validator(self):
""" The validator whose schema is being validated. """
return self._config['target_validator']
def _validate_logical(self, rule, field, value):
""" {'allowed': ('allof', 'anyof', 'noneof', 'oneof')} """
validator = self._get_child_validator(
document_crumb=rule,
schema=self.root_allow_unknown['schema'],
allow_unknown=self.root_allow_unknown['allow_unknown']
)
for constraints in value:
_hash = mapping_hash({'turing': constraints})
if _hash in self.target_validator._valid_schemas:
continue
validator(constraints, normalize=False)
if validator._errors:
self._error(validator._errors)
else:
self.target_validator._valid_schemas.add(_hash)
def _validate_type_callable(self, value):
if isinstance(value, Callable):
return True
def _validate_type_hashable(self, value):
if isinstance(value, Hashable):
return True
def _validate_type_hashables(self, value):
if self._validate_type_list(value):
return all(self._validate_type_hashable(x) for x in value)
def _validator_bulk_schema(self, field, value):
if isinstance(value, _str_type):
if value in self.known_rules_set_refs:
return
else:
self.known_rules_set_refs += (value,)
definition = self.target_validator.rules_set_registry.get(value)
if definition is None:
path = self.document_path + (field,)
self._error(path, 'Rules set definition %s not found.' % value)
return
else:
value = definition
_hash = mapping_hash({'turing': value})
if _hash in self.target_validator._valid_schemas:
return
validator = self._get_child_validator(
document_crumb=field,
schema=self.root_allow_unknown['schema'],
allow_unknown=self.root_allow_unknown['allow_unknown'])
validator(value, normalize=False)
if validator._errors:
self._error(validator._errors)
else:
self.target_validator._valid_schemas.add(_hash)
def _validator_handler(self, field, value):
if isinstance(value, Callable):
return
if isinstance(value, _str_type):
if value not in self.target_validator.validators + \
self.target_validator.coercers:
self._error(field, '%s is no valid coercer' % value)
elif isinstance(value, Iterable):
for handler in value:
self._validator_handler(field, handler)
def _validator_items(self, field, value):
for i, schema in enumerate(value):
self._validator_bulk_schema((field, i), schema)
def _validator_schema(self, field, value):
if isinstance(value, _str_type):
if value in self.known_schema_refs:
return
else:
self.known_schema_refs += (value,)
definition = self.target_validator.schema_registry.get(value)
if definition is None:
path = self.document_path + (field,)
self._error(path, 'Schema definition %s not found.' % value)
return
else:
value = definition
_hash = mapping_hash(value)
if _hash in self.target_validator._valid_schemas:
return
validator = self._get_child_validator(
document_crumb=field,
schema=None, allow_unknown=self.root_allow_unknown)
validator(value, normalize=False)
if validator._errors:
self._error(validator._errors)
else:
self.target_validator._valid_schemas.add(_hash)
####
class Registry(object):
""" A registry to store and retrieve schemas and parts of it by a name
that can be used in validation schemas.
:param definitions: Optional, initial definitions.
:type definitions: any :term:`mapping` """
def __init__(self, definitions={}):
self._storage = {}
self.extend(definitions)
def add(self, name, definition):
""" Register a definition to the registry. Existing definitions are
replaced silently.
:param name: The name which can be used as reference in a validation
schema.
:type name: :class:`str`
:param definition: The definition.
:type definition: any :term:`mapping` """
self._storage[name] = self._expand_definition(definition)
def all(self):
""" Returns a :class:`dict` with all registered definitions mapped to
their name. """
return self._storage
def extend(self, definitions):
""" Add several definitions at once. Existing definitions are
replaced silently.
:param definitions: The names and definitions.
:type definitions: a :term:`mapping` or an :term:`iterable` with
two-value :class:`tuple` s """
for name, definition in dict(definitions).items():
self.add(name, definition)
def clear(self):
""" Purge all definitions in the registry. """
self._storage.clear()
def get(self, name, default=None):
""" Retrieve a definition from the registry.
:param name: The reference that points to the definition.
:type name: :class:`str`
:param default: Return value if the reference isn't registered. """
return self._storage.get(name, default)
def remove(self, *names):
""" Unregister definitions from the registry.
:param names: The names of the definitions that are to be
unregistered. """
for name in names:
self._storage.pop(name, None)
class SchemaRegistry(Registry):
@classmethod
def _expand_definition(cls, definition):
return DefinitionSchema.expand(definition)
class RulesSetRegistry(Registry):
@classmethod
def _expand_definition(cls, definition):
return DefinitionSchema.expand({0: definition})[0]
schema_registry, rules_set_registry = SchemaRegistry(), RulesSetRegistry()