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helm/expandybird/expansion/schema_validation_utils.py

97 lines
3.4 KiB

# Copyright 2015 The Kubernetes Authors All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Helper functions for Schema Validation."""
import jsonschema
DEFAULT = 'default'
PROPERTIES = 'properties'
REF = '$ref'
REQUIRED = 'required'
def ExtendWithDefault(validator_class):
"""Takes a validator and makes it set default values on properties.
Args:
validator_class: A class to add our overridden validators to
Returns:
A validator_class that will set default values and ignore required fields
"""
validate_properties = validator_class.VALIDATORS['properties']
def SetDefaultsInProperties(validator, user_schema, user_properties,
parent_schema):
SetDefaults(validator, user_schema or {}, user_properties, parent_schema,
validate_properties)
return jsonschema.validators.extend(
validator_class, {PROPERTIES: SetDefaultsInProperties,
REQUIRED: IgnoreKeyword})
def SetDefaults(validator, user_schema, user_properties, parent_schema,
validate_properties):
"""Populate the default values of properties.
Args:
validator: A generator that validates the "properties" keyword of the schema
user_schema: Schema which might define defaults, might be a nested part of
the entire schema file.
user_properties: User provided values which we are setting defaults on
parent_schema: Schema object that contains the schema being evaluated on
this pass, user_schema.
validate_properties: Validator function, called recursively.
"""
for schema_property, subschema in user_schema.iteritems():
# The ordering of these conditions assumes that '$ref' blocks override
# all other schema info, which is what the jsonschema library assumes.
# If the subschema has a reference,
# see if that reference defines a 'default' value
if REF in subschema:
out = ResolveReferencedDefault(validator, subschema[REF])
user_properties.setdefault(schema_property, out)
# Otherwise, see if the subschema has a 'default' value
elif DEFAULT in subschema:
user_properties.setdefault(schema_property, subschema[DEFAULT])
# Recursively apply defaults. This is a generator, so we must wrap with list()
list(validate_properties(validator, user_schema,
user_properties, parent_schema))
def ResolveReferencedDefault(validator, ref):
"""Resolves a reference, and returns any default value it defines.
Args:
validator: A generator that validates the "$ref" keyword
ref: The target of the "$ref" keyword
Returns:
The value of the 'default' field found in the referenced schema, or None
"""
with validator.resolver.resolving(ref) as resolved:
if DEFAULT in resolved:
return resolved[DEFAULT]
def IgnoreKeyword(
unused_validator, unused_required, unused_instance, unused_schema):
"""Validator for JsonSchema that does nothing."""
pass