community.general/plugins/filter/keep_keys.py

# -*- coding: utf-8 -*-
# Copyright (c) 2024 Vladimir Botka <vbotka@gmail.com>
# Copyright (c) 2024 Felix Fontein <felix@fontein.de>
# GNU General Public License v3.0+ (see LICENSES/GPL-3.0-or-later.txt or https://www.gnu.org/licenses/gpl-3.0.txt)
# SPDX-License-Identifier: GPL-3.0-or-later

from __future__ import (absolute_import, division, print_function)
__metaclass__ = type

DOCUMENTATION = '''
    name: keep_keys
    short_description: Keep specific keys from dictionaries in a list
    version_added: "9.1.0"
    author:
      - Vladimir Botka (@vbotka)
      - Felix Fontein (@felixfontein)
    description: This filter keeps only specified keys from a provided list of dictionaries.
    options:
      _input:
        description:
          - A list of dictionaries.
          - Top level keys must be strings.
        type: list
        elements: dictionary
        required: true
      target:
        description:
          - A single key or key pattern to keep, or a list of keys or keys patterns to keep.
          - If O(matching_parameter=regex) there must be exactly one pattern provided.
        type: raw
        required: true
      matching_parameter:
        description: Specify the matching option of target keys.
        type: str
        default: equal
        choices:
          equal: Matches keys of exactly one of the O(target) items.
          starts_with: Matches keys that start with one of the O(target) items.
          ends_with: Matches keys that end with one of the O(target) items.
          regex:
            - Matches keys that match the regular expresion provided in O(target).
            - In this case, O(target) must be a regex string or a list with single regex string.
'''

EXAMPLES = '''
  l:
    - {k0_x0: A0, k1_x1: B0, k2_x2: [C0], k3_x3: foo}
    - {k0_x0: A1, k1_x1: B1, k2_x2: [C1], k3_x3: bar}

  # 1) By default match keys that equal any of the items in the target.
  t: [k0_x0, k1_x1]
  r: "{{ l | community.general.keep_keys(target=t) }}"

  # 2) Match keys that start with any of the items in the target.
  t: [k0, k1]
  r: "{{ l | community.general.keep_keys(target=t, matching_parameter='starts_with') }}"

  # 3) Match keys that end with any of the items in target.
  t: [x0, x1]
  r: "{{ l | community.general.keep_keys(target=t, matching_parameter='ends_with') }}"

  # 4) Match keys by the regex.
  t: ['^.*[01]_x.*$']
  r: "{{ l | community.general.keep_keys(target=t, matching_parameter='regex') }}"

  # 5) Match keys by the regex.
  t: '^.*[01]_x.*$'
  r: "{{ l | community.general.keep_keys(target=t, matching_parameter='regex') }}"

  # The results of above examples 1-5 are all the same.
  r:
    - {k0_x0: A0, k1_x1: B0}
    - {k0_x0: A1, k1_x1: B1}

  # 6) By default match keys that equal the target.
  t: k0_x0
  r: "{{ l | community.general.keep_keys(target=t) }}"

  # 7) Match keys that start with the target.
  t: k0
  r: "{{ l | community.general.keep_keys(target=t, matching_parameter='starts_with') }}"

  # 8) Match keys that end with the target.
  t: x0
  r: "{{ l | community.general.keep_keys(target=t, matching_parameter='ends_with') }}"

  # 9) Match keys by the regex.
  t: '^.*0_x.*$'
  r: "{{ l | community.general.keep_keys(target=t, matching_parameter='regex') }}"

  # The results of above examples 6-9 are all the same.
  r:
    - {k0_x0: A0}
    - {k0_x0: A1}
'''

RETURN = '''
  _value:
    description: The list of dictionaries with selected keys.
    type: list
    elements: dictionary
'''

from ansible_collections.community.general.plugins.plugin_utils.keys_filter import (
    _keys_filter_params,
    _keys_filter_target_str)


def keep_keys(data, target=None, matching_parameter='equal'):
    """keep specific keys from dictionaries in a list"""

    # test parameters
    _keys_filter_params(data, matching_parameter)
    # test and transform target
    tt = _keys_filter_target_str(target, matching_parameter)

    if matching_parameter == 'equal':
        def keep_key(key):
            return key in tt
    elif matching_parameter == 'starts_with':
        def keep_key(key):
            return key.startswith(tt)
    elif matching_parameter == 'ends_with':
        def keep_key(key):
            return key.endswith(tt)
    elif matching_parameter == 'regex':
        def keep_key(key):
            return tt.match(key) is not None

    return [{k: v for k, v in d.items() if keep_key(k)} for d in data]


class FilterModule(object):

    def filters(self):
        return {
            'keep_keys': keep_keys,
        }