Mini Shell
from __future__ import absolute_import
from warnings import warn
from cerberus import errors
from cerberus.platform import (
_str_type,
Callable,
Hashable,
Mapping,
MutableMapping,
Sequence,
)
from cerberus.utils import (
get_Validator_class,
validator_factory,
mapping_hash,
TypeDefinition,
)
class _Abort(Exception):
pass
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)
types_mapping = SchemaValidator.types_mapping.copy()
types_mapping.update(
{
'callable': TypeDefinition('callable', (Callable,), ()),
'hashable': TypeDefinition('hashable', (Hashable,), ()),
}
)
SchemaValidator.types_mapping = types_mapping
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):
if hasattr(self, "schema"):
return str(self.schema)
else:
return "No schema data is set yet."
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
# TODO remove this with the next major release
schema = cls._rename_deprecated_rulenames(schema)
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, rules in schema.items():
for of_rule in [x for x in rules if is_of_rule(x)]:
operator, rule = of_rule.split('_', 1)
rules.update({operator: []})
for value in rules[of_rule]:
rules[operator].append({rule: value})
del rules[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]
# TODO remove the last two values in the tuple with the next major release
for rule in ('keysrules', 'valuesrules', '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]:
if not isinstance(schema[field][rule], Sequence):
continue
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 get(self, item, default=None):
return self.schema.get(item, default)
def items(self):
return self.schema.items()
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
# TODO remove with next major release
@staticmethod
def _rename_deprecated_rulenames(schema):
for field, rules in schema.items():
if isinstance(rules, str): # registry reference
continue
for old, new in (
('keyschema', 'keysrules'),
('validator', 'check_with'),
('valueschema', 'valuesrules'),
):
if old not in rules:
continue
if new in rules:
raise RuntimeError(
"The rule '{new}' is also present with its old "
"name '{old}' in the same set of rules."
)
warn(
"The rule '{old}' was renamed to '{new}'. The old name will "
"not be available in the next major release of "
"Cerberus.".format(old=old, new=new),
DeprecationWarning,
)
schema[field][new] = schema[field][old]
schema[field].pop(old)
return schema
def regenerate_validation_schema(self):
self.validation_schema = SchemaValidationSchema(self.validator)
def validate(self, schema=None):
"""
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 the assigned Validator object.
Raises a :class:`~cerberus.base.SchemaError` when an invalid
schema is encountered.
"""
if schema is None:
schema = self.schema
_hash = (mapping_hash(schema), mapping_hash(self.validator.types_mapping))
if _hash not in self.validator._valid_schemas:
self._validate(schema)
self.validator._valid_schemas.add(_hash)
def _validate(self, schema):
if isinstance(schema, _str_type):
schema = self.validator.schema_registry.get(schema, schema)
test_schema = {}
for field, rules in schema.items():
if isinstance(rules, _str_type):
test_schema[field] = rules_set_registry.get(rules, rules)
else:
test_rules = {}
for rule, constraint in rules.items():
test_rules[rule.replace(" ", "_")] = constraint
test_schema[field] = test_rules
if not self.schema_validator(test_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
def copy(self):
# Override ancestor's copy, because
# UnvalidatedSchema does not have .validator:
return self.__class__(self.schema.copy())
class SchemaValidationSchema(UnvalidatedSchema):
def __init__(self, validator):
self.schema = {
'allow_unknown': False,
'schema': validator.rules,
'type': 'dict',
}
class SchemaValidatorMixin(object):
"""
This validator mixin provides mechanics to validate schemas passed to a Cerberus
validator.
"""
def __init__(self, *args, **kwargs):
kwargs.setdefault('known_rules_set_refs', set())
kwargs.setdefault('known_schema_refs', set())
super(SchemaValidatorMixin, self).__init__(*args, **kwargs)
@property
def known_rules_set_refs(self):
"""The encountered references to rules set registry items."""
return self._config['known_rules_set_refs']
@property
def known_schema_refs(self):
"""The encountered references to schema registry items."""
return self._config['known_schema_refs']
@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 _check_with_bulk_schema(self, field, value):
# resolve schema registry reference
if isinstance(value, _str_type):
if value in self.known_rules_set_refs:
return
else:
self.known_rules_set_refs.add(value)
definition = self.target_validator.rules_set_registry.get(value)
if definition is None:
self._error(field, 'Rules set definition %s not found.' % value)
return
else:
value = definition
_hash = (
mapping_hash({'turing': value}),
mapping_hash(self.target_validator.types_mapping),
)
if _hash in self.target_validator._valid_schemas:
return
validator = self._get_child_validator(
document_crumb=field,
allow_unknown=False,
schema=self.target_validator.rules,
)
validator(value, normalize=False)
if validator._errors:
self._error(validator._errors)
else:
self.target_validator._valid_schemas.add(_hash)
def _check_with_dependencies(self, field, value):
if isinstance(value, _str_type):
pass
elif isinstance(value, Mapping):
validator = self._get_child_validator(
document_crumb=field,
schema={'valuesrules': {'type': 'list'}},
allow_unknown=True,
)
if not validator(value, normalize=False):
self._error(validator._errors)
elif isinstance(value, Sequence):
if not all(isinstance(x, Hashable) for x in value):
path = self.document_path + (field,)
self._error(path, 'All dependencies must be a hashable type.')
def _check_with_items(self, field, value):
for i, schema in enumerate(value):
self._check_with_bulk_schema((field, i), schema)
def _check_with_schema(self, field, value):
try:
value = self._handle_schema_reference_for_validator(field, value)
except _Abort:
return
_hash = (mapping_hash(value), mapping_hash(self.target_validator.types_mapping))
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(self._expand_rules_set_refs(value), normalize=False)
if validator._errors:
self._error(validator._errors)
else:
self.target_validator._valid_schemas.add(_hash)
def _check_with_type(self, field, value):
value = set((value,)) if isinstance(value, _str_type) else set(value)
invalid_constraints = value - set(self.target_validator.types)
if invalid_constraints:
self._error(
field, 'Unsupported types: {}'.format(', '.join(invalid_constraints))
)
def _expand_rules_set_refs(self, schema):
result = {}
for k, v in schema.items():
if isinstance(v, _str_type):
result[k] = self.target_validator.rules_set_registry.get(v)
else:
result[k] = v
return result
def _handle_schema_reference_for_validator(self, field, value):
if not isinstance(value, _str_type):
return value
if value in self.known_schema_refs:
raise _Abort
self.known_schema_refs.add(value)
definition = self.target_validator.schema_registry.get(value)
if definition is None:
path = self.document_path + (field,)
self._error(path, 'Schema definition {} not found.'.format(value))
raise _Abort
return definition
def _validate_logical(self, rule, field, value):
"""{'allowed': ('allof', 'anyof', 'noneof', 'oneof')}"""
if not isinstance(value, Sequence):
self._error(field, errors.BAD_TYPE)
return
validator = self._get_child_validator(
document_crumb=rule,
allow_unknown=False,
schema=self.target_validator.validation_rules,
)
for constraints in value:
_hash = (
mapping_hash({'turing': constraints}),
mapping_hash(self.target_validator.types_mapping),
)
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)
####
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 clear(self):
"""Purge all definitions in the registry."""
self._storage.clear()
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 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()
Zerion Mini Shell 1.0