Source code for hifis_surveyval.models.mixins.yaml_constructable

# hifis-surveyval
# Framework to help developing analysis scripts for the HIFIS Software survey.
#
# SPDX-FileCopyrightText: 2021 HIFIS Software <support@hifis.net>
#
# SPDX-License-Identifier: GPL-3.0-or-later
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
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# along with this program. If not, see <http://www.gnu.org/licenses/>.

"""
Provides an abstract class for classes constructed from YAML-Dictionaries.

All of these inheriting classes should define a Schema to dictate the required
structure of the YAML to be parsed.
"""

from abc import ABC, abstractmethod
from typing import Dict, List, Union

from schema import Or, Schema

# A shorthand type for the kind of lists and dictionaries that can be
# encountered when parsing YAML data
YamlList = List[Union[str, "YamlDict"]]
YamlDict = Dict[str, Union[str, "YamlList", "YamlDict"]]


[docs]class YamlConstructable(ABC): """ An abstract class for classes that can be instantiated from a YamlDict. It defines a catchall schema that accepts everything that looks like a valid YAML mapping. """ schema: Schema = Schema({str: Or(str, list, dict)}) """ The default schema of a YamlConstructable validates everything which is formatted like a YamlDictionary""" @staticmethod @abstractmethod def _from_yaml_dictionary(yaml: YamlDict, **kwargs) -> "YamlConstructable": """ Instantiate an object of this class from a given YamlDict. This must be overridden by inheriting classes. Args: yaml: A dictionary containing the data required to create a new instance of the inheriting class. The dictionary has been validated against the schema provided by the inheriting class. Returns: A new instance of the overriding subclass """ pass
[docs] @classmethod def from_yaml_dictionary( cls, yaml: YamlDict, **kwargs ) -> "YamlConstructable": """ Instantiate an object of this class from a given YamlDict. The given YAML will be validated against the schema defined for the class. If the class did not define a schema on its own (although it should) a catchall schema is provided. Args: yaml: A dictionary as received from the YAML parser containing the data required to create a new instance of the inheriting class Returns: A new instance of the overriding subclass """ schema: Schema = cls.schema validated_yaml = schema.validate(yaml) return cls._from_yaml_dictionary(yaml=validated_yaml, **kwargs)