Modify JSON in Ansible

Not a direct answer to your question about the error with modify_json but a working solution.

I would go with jq for that. jq is a lightweight and flexible command-line JSON processor and available for nearly every Linux distribution. When not, use the prebuilt binaries that come without dependencies.

As the website states:

jq is like sed for JSON data - you can use it to slice and filter and map and transform structured data with the same ease that sed, awk, grep and friends let you play with text.

I shrinked your play to a minimal working solution with the same result. The jq executable must be in the PATH of the system it is running on. Feel free to customize it to your needs.

---- name: Sync Power Schedules From Database to Survey Spec  hosts: localhost  gather_facts: no  vars:    choices_key: ".spec[6].choices"    choices_value: "23:00-02:00\n02:00-04:00\n04:00-06:00\n00:00-04:00"    json_file: "{{playbook_dir}}/s.json"  tasks:  - name: "modify json"    command: >      jq "{{choices_key}}=\"{{choices_value}}\"" "{{json_file}}"    register: json  - debug:      var: json.stdout

I think this is more elegant as the solution with the extra json_modify.py module. For more information on jq please see the manual page.

There's just a couple of minor issues in your playbook

1. You are loading the json data from the file as a string, rather than json/dict. Instead of your command/cat task, use this to load the data in:

    - set_fact:     surveySpec: "{{ lookup('file', sharedDataPathFile) | from_json }}"

2. The other problem you would have hit is you are attempting to update just the choices value (i.e. a string), rather than the choices dict item. Just a small change required in your json_modify pointer:

    - json_modify:     data: "{{ surveySpec }}"     pointer: "/spec/5"     action: update     update: "{{ new_choices }}"   register: result

One other thing .. the array index is 5, not 6