Ansible: split a dictionary with list values to a list of dictionaries with a single item from the l-CodePudding

I need to convert a dictionary with list values into a list of dictionaries.

Given:

my_dict:
  key1: ["111", "222"]
  key2: ["444", "555"]

Desired output:

my_list:
 - key1: "111"
   key2: "444"
 - key1: "222"
   key2: "555"

What I've tried:

  - set_fact:
      my_list: "{{ my_list | default([])   [{item.0.key: item.1}] }}"
    loop: "{{ my_dict | dict2items | subelements('value') }}"

And what I've got:

[
            {
                "key1": "111"
            },
            {
                "key1": "222"
            },
            {
                "key2": "444"
            },
            {
                "key2": "555"
            } 
        ]

Thankful for any help and suggestions!

CodePudding user response：

Get the keys and values of the dictionary first

keys: "{{ my_dict.keys()|list }}"
vals: "{{ my_dict.values()|list }}"

gives

keys: [key1, key2]
vals:
  - ['111', '222']
  - ['444', '555']

Transpose the values

    - set_fact:
        tvals: "{{ tvals|d(vals.0)|zip(item)|map('flatten') }}"
      loop: "{{ vals[1:] }}"

gives

tvals:
  - ['111', '444']
  - ['222', '555']

Create the list of the dictionaries

my_list: "{{ tvals|map('zip', keys)|
                   map('map', 'reverse')|
                   map('community.general.dict')|
                   list }}"

gives

my_list:
  - key1: '111'
    key2: '444'
  - key1: '222'
    key2: '555'

^{Notes

Example of a complete playbook

- hosts: localhost
vars:
my_dict:
key1: ["111", "222"]
key2: ["444", "555"]
keys: "{{ my_dict.keys()|list }}"
vals: "{{ my_dict.values()|list }}"
my_list: "{{ tvals|map('zip', keys)|
map('map', 'reverse')|
map('community.general.dict')|
list }}"
tasks:
- set_fact:
tvals: "{{ tvals|d(vals.0)|zip(item)|map('flatten') }}"
loop: "{{ vals[1:] }}"
- debug:
var: my_list

You can use a custom filer to transpose the matrix. For example,

shell> cat filter_plugins/numpy.py
# All rights reserved (c) 2022, Vladimir Botka <[email protected]>
# Simplified BSD License, https://opensource.org/licenses/BSD-2-Clause

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

from ansible.errors import AnsibleFilterError
from ansible.module_utils.common._collections_compat import Sequence

import json
import numpy

def numpy_transpose(arr):
if not isinstance(arr, Sequence):
raise AnsibleFilterError('First argument for numpy_transpose must be list. %s is %s' %
(arr, type(arr)))
arr1 = numpy.array(arr)
arr2 = arr1.transpose()
return json.dumps(arr2.tolist())

class FilterModule(object):
''' Ansible wrappers for Python NumPy methods '''

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

Then you can avoid iteration. For example, the playbook below gives the same result
- hosts: localhost
vars:
my_dict:
key1: ["111", "222"]
key2: ["444", "555"]
keys: "{{ my_dict.keys()|list }}"
vals: "{{ my_dict.values()|list }}"
tvals: "{{ vals|numpy_transpose()|from_yaml }}"
my_list: "{{ tvals|map('zip', keys)|
map('map', 'reverse')|
map('community.general.dict')|
list }}"
tasks:
- debug:
var: my_list

Transposing explained

Let's start with the matrix 2x2
vals:
- ['111', '222']
- ['444', '555']

The task below
- set_fact:
tvals: "{{ tvals|d(vals.0)|zip(item) }}"
loop: "{{ vals[1:] }}"

gives step by step:
a) Before the iteration starts the variable tvals is assigned the default value vals.0
vals.0: ['111', '222']

b) The task iterates the list vals[1:]. These are all lines in the array except the first one
vals[1:]:
- ['444', '555']

c) The first, and the only one, iteration zip the first and the second line. This is the result
vals.0|zip(vals.1):
- ['111', '444']
- ['222', '555']

Let's proceed with matrix 3x3
vals:
- ['111', '222', '333']
- ['444', '555', '666']
- ['777', '888', '999']

The task below
- set_fact:
tvals: "{{ tvals|d(vals.0)|zip(item)|map('flatten') }}"
loop: "{{ vals[1:] }}"

gives step by step:
a) Before the iteration starts the variable tvals is assigned the default value vals.0
vals.0: ['111', '222', '333']

b) The task iterates the list vals[1:]
vals[1:]:
- ['444', '555', '666']
- ['777', '888', '999']

c) The first iteration zip the first and the second line, and assigns it to tvals. The filer flatten has no effect on the lines
vals.0|zip(vals.1)|map('flatten'):
- ['111', '444']
- ['222', '555']
- ['333', '666']

d) The next iteration zip tvals and the third line
tvals|zip(vals.2):
- - ['111', '444']
- '777'
- - ['222', '555']
- '888'
- - ['333', '666']
- '999

e) The lines must be flattened. This is the result
tvals|zip(vals.2)|map('flatten'):
- ['111', '444', '777']
- ['222', '555', '888']
- ['333', '666', '999']}