Source code for yggdrasil.metaschema.properties.MetaschemaProperty

import six
import jsonschema
from yggdrasil.metaschema.properties import MetaschemaPropertyMeta


[docs]@six.add_metaclass(MetaschemaPropertyMeta) class MetaschemaProperty(object): r"""Base class for adding properties to the metaschema. Class Attributes: name (str): Name of the property. [REQUIRED] schema (dict): JSON schema describing valid values for the property. [REQUIRED] types (list): Types of instances that the property is valid for. [AUTOMATED] python_types (list): Python types of instances that the property is valid for. [AUTOMATED] """ name = 'base' schema = None types = tuple() python_types = tuple() _encode = None _validate = None _compare = None _replaces_existing = False _skip_existing_validator = False _skip_formulaic_validator = False _dont_register = False
[docs] @classmethod def encode(cls, instance, typedef=None): r"""Method to encode the property given the object. Args: instance (object): Object to get property for. typedef (object, None): Template value in type definition to use for initializing encoding some cases. Defaults to None and is ignored. Returns: object: Encoded property for instance. """ if cls._encode is not None: return cls._encode(instance, typedef=typedef) raise NotImplementedError("Encode method not set.")
[docs] @classmethod def validate(cls, validator, value, instance, schema): r"""Validator for JSON schema validation of an instance by this property. If there is not a user provided validate function, the instance will be encoded and then the encoded value will be checked against the provided value using cls.compare. Args: validator (jsonschmea.Validator): JSON schema validator. value (object): Value of the property in the schema. instance (object): Instance to validate. schema (dict): Schema that instance should be validated against. Yields: str: Error messages associated with failed validation. """ errors = [] if cls._validate is False: pass elif cls._validate is not None: errors = cls._validate(validator, value, instance, schema) or () elif not cls._skip_formulaic_validator: is_type = False for t in cls.types: if validator.is_type(instance, t): is_type = True break if is_type: x = cls.encode(instance, typedef=value) errors = cls.compare(x, value) or () for e in errors: yield e
[docs] @classmethod def compare(cls, prop1, prop2, root1=None, root2=None): r"""Method to determine compatiblity of one property value with another. This method is not necessarily symmetric in that the second value may not be compatible with the first even if the first is compatible with the second. Args: prop1 (object): Property value to compare against prop2. prop2 (object): Property value to compare against. Yields: str: Comparision failure messages. """ if cls._compare is not None: errors = cls._compare(prop1, prop2) or () for e in errors: yield e else: if (prop1 != prop2): yield '%s is not equal to %s' % (prop1, prop2)
[docs] @classmethod def normalize(cls, validator, value, instance, schema): r"""Method to normalize the instance based on the property value. Args: validator (Validator): Validator class. value (object): Property value. instance (object): Object to normalize. schema (dict): Schema containing this property. Returns: object: Normalized object. """ return instance
[docs] @classmethod def normalize_in_schema(cls, schema): r"""Method to normalize the entry for this property in a schema. Args: schema (dict): Schema to normalize. Returns: dict: Normalized schema. """ return schema
[docs] @classmethod def post_validate(cls, validator, value, instance, schema): r"""Actions performed after validation if normalizing.""" pass
[docs] @classmethod def wrapped_validate(cls, validator, value, instance, schema): r"""Wrapped validator that handles errors produced by the native validate method and ensures that the property is parsed by the base validator and raises the correct error if necessary. Args: *args: All arguments are passed to the validate class method. **kwargs: All keyword arguments are passed to the validate class method. """ if validator._normalizing: validator._normalized = cls.normalize(validator, value, validator._normalized, schema) instance = validator._normalized try: failed = False errors = cls.validate(validator, value, instance, schema) or () for e in errors: failed = True yield jsonschema.ValidationError(e) if (((not failed) and (not cls._skip_existing_validator) and (cls.name in validator._base_validator.VALIDATORS))): errors = validator._base_validator.VALIDATORS[cls.name]( validator, value, instance, schema) or () for e in errors: failed = True yield e finally: if validator._normalizing and (not failed): cls.post_validate(validator, value, instance, schema)
[docs]def create_property(name, schema, encode, validate=None, compare=None, dont_register=False): r"""Create a new property class. Args: name (str): Name of the property. schema (dict): JSON schema describing valid values for the property. encode (function): Function to encode the property based on a provided instance. The function must take an instance as input and return the value of the property for that instance. validate (function, optional): Function to determine if an instance is valid under the contraint of this property. The function must take as input a jsonschema validator, a property value, an instance to evaluate, and the schema. The function must return a boolean: True if the instance is valid, False otherwise. See cls.validate for additional information and default behavior. compare (function, optional): Function to determine if two property values are compatible. The function must take as input two property values and return a boolean: True if the first property is compatible with the second, False otherwise. See cls.compare for additional information and default behavior. dont_register (bool, optional): If True, the created property will not be registered. Defaults to False. """ attr_dict = {'name': name, 'schema': schema, '_dont_register': dont_register} for k, x in zip(['_encode', '_validate', '_compare'], [encode, validate, compare]): if x is not None: attr_dict[k] = staticmethod(x) out = type(name, (MetaschemaProperty, ), attr_dict) return out