Source code for monk.manipulation

# -*- coding: utf-8 -*-
#    Monk is an unobtrusive data modeling, manipulation and validation library.
#    Copyright © 2011—2014  Andrey Mikhaylenko
#    This file is part of Monk.
#    Monk is free software: you can redistribute it and/or modify
#    it under the terms of the GNU Lesser General Public License as published
#    by the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#    Monk is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    GNU Lesser General Public License for more details.
#    You should have received a copy of the GNU Lesser General Public License
#    along with Monk.  If not, see <>.
Data manipulation
from .compat import text_type
from . import translate

__all__ = [
    # functions
    # helpers
    'normalize_to_list', 'normalize_list_of_dicts',

[docs]def merge_defaults(spec, value): """ Returns a copy of `value` recursively updated to match the `spec`: * New values are added whenever possible (including nested ones). * Existing values are never changed or removed. * Exception: container values (lists, dictionaries) may be populated; see respective merger functions for details. The result may not pass validation against the `spec` in the following cases: a) a required value is missing and the spec does not provide defaults; b) an existing value is invalid. The business logic is as follows: * if `value` is empty, use default value from `spec`; * if `value` is present or `spec` has no default value: * if `spec` datatype is present as a key in `mergers`, use the respective merger function to obtain the value; * if no merger is assigned to the datatype, use `fallback` function. See documentation on concrete merger functions for further details. :spec: A "natural" or "verbose" spec. :value: The value to merge into the `spec`. Examples:: >>> merge_defaults('foo', None) 'foo' >>> merge_defaults('foo', 'bar') 'bar' >>> merge_defaults({'a': 'foo'}, {}) {'a': 'foo'} >>> merge_defaults({'a': [{'b': 123}]}, ... {'a': [{'b': None}, ... {'x': 0}]}) {'a': [{'b': 123}, {'b': 123, 'x': 0}]} """ validator = translate(spec) return validator.get_default_for(value)
class UNDEFINED: pass
[docs]def normalize_to_list(value): """ Converts given value to a list as follows: * ``[x]`` → ``[x]`` * ``x`` → ``[x]`` """ if value and not isinstance(value, list): return [value] else: return value
[docs]def normalize_list_of_dicts(value, default_key, default_value=UNDEFINED): """ Converts given value to a list of dictionaries as follows: * ``[{...}]`` → ``[{...}]`` * ``{...}`` → ``[{...}]`` * ``'xyz'`` → ``[{default_key: 'xyz'}]`` * ``None`` → ``[{default_key: default_value}]`` (if specified) * ``None`` → ``[]`` :param default_value: only Unicode, i.e. `str` in Python 3.x and **only** `unicode` in Python 2.x """ if value is None: if default_value is UNDEFINED: return [] value = default_value if isinstance(value, dict): return [value] if isinstance(value, text_type): return [{default_key: value}] if isinstance(value, list): if not all(isinstance(x, dict) for x in value): def _fix(x): return {default_key: x} if isinstance(x, text_type) else x return list(map(_fix, value)) return value