Way to ensure that string is in JSON format

user_14752435 0
Viewed 480

In an Ansible task I'd like to test if string is json prior to use it with from_json.

fatal: [localhost]: FAILED! =>
  msg: |-
    the field 'args' has an invalid value ({u'tojson': u'{{ notjson | from_json}}'}), and could not be converted to an dict.The error was: No JSON object could be decoded

Thanks in advance for your help.

ansible json
1 Answers

Invalid JSON will fail. For example

    - set_fact:
        json_parsed: "{{ json_str|from_json }}"
      vars:
        json_str: 'invalid JSON'

TASK [set_fact] ****
fatal: [localhost]: FAILED! => 
  msg: |-
    the field 'args' has an invalid value ({'json_parsed': '{{ json_str|from_json }}'}), and could not be converted to an dict.The error was: Expecting value: line 1 column 1 (char 0)
  
    The error appears to be in '/export/scratch/tmp/test-145.yml': line 21, column 7, but may
    be elsewhere in the file depending on the exact syntax problem.
  
    The offending line appears to be:
  
  
        - set_fact:
          ^ here

It's possible to handle the error. For example

    - set_fact:
        json_parsed: "{{ json_str|from_json }}"
      vars:
        json_str: 'invalid JSON'
      ignore_errors: true
      register: result
    - debug:
        msg: "{{ result.msg }}"
      when: result.failed

TASK [debug] ****
ok: [localhost] => 
  msg: |-
    the field 'args' has an invalid value ({'json_parsed': '{{ json_str|from_json }}'}), and could not be converted to an dict.The error was: Expecting value: line 1 column 1 (char 0)
  
    The error appears to be in '/export/scratch/tmp/test-145.yml': line 11, column 7, but may
    be elsewhere in the file depending on the exact syntax problem.
  
    The offending line appears to be:
  
  
        - set_fact:
          ^ here
user_64825610
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