Source code for cis_interface.metaschema.properties.MetaschemaProperty
import jsonschema
[docs]class MetaschemaProperty(object):
r"""Base class for adding properties to the metaschema.
Attributes:
name (str): Name of the property.
schema (dict): JSON schema describing valid values for the property.
types (list): Types of instances that the property is valid for.
python_types (list): Python types of instances that the property is
valid for.
"""
name = 'base'
schema = None
types = tuple()
python_types = tuple()
_encode = None
_validate = None
_compare = None
_replaces_existing = 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 ()
else:
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 validator._normalized
[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, instance, 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 (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):
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.
"""
attr_dict = {'name': name, 'schema': schema}
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