Inline encrypted variable not JSON serializable

Question

I'm trying to understand how to encrypt single variables with vault. First I encrypt the string with ansible-vault encrypt_string -n -p, then I write the output into my playbook. When I execute the playbook it says that the decrypted string isn't JSON serializable.

Encrypted string: "inline_name" I also tried it with inline_name and inlinename, every time with the same result.

My playbook:

---
- name: Build System

  hosts: dev

  tasks:
  - name: Create 
    mysql_db:
      state: present
      name: !vault |
          $ANSIBLE_VAULT;1.1;AES256
          39613261386438623937643062636166663638633062323939343734306334346537613233623064
          3761633832326365356231633338396132646532313861350a316666376566616633376238313636
          39343833306462323534623238333639663734626662623731666239366566643636386261643164
          3861363730336331660a316165633232323732633364346636363764623639356562336536636136
          6364
      login_host: "{{ mysql_host }}"
      login_user: "{{ mysql_user }}"
      login_password: "{{ mysql_pass }}"
  - name: Check if can access plain text vars
    debug:
      msg: "{{ my_plain_txt }}"

Error message:

An exception occurred during task execution. To see the full traceback, use -vvv. 
The error was: TypeError: u'"inline_name"' is not JSON serializable
fatal: [127.0.0.1]: FAILED! => {"failed": true, "msg": "Unexpected failure during module execution.", "stdout": ""}

Answer 1

Add task-level variable:

  - name: Create 
    mysql_db:
      state: present
      name: "{{ mysql_name }}"
      login_host: "{{ mysql_host }}"
      login_user: "{{ mysql_user }}"
      login_password: "{{ mysql_pass }}"
    vars:
      mysql_name: !vault |
          $ANSIBLE_VAULT;1.1;AES256
          39613261386438623937643062636166663638633062323939343734306334346537613233623064
          3761633832326365356231633338396132646532313861350a316666376566616633376238313636
          39343833306462323534623238333639663734626662623731666239366566643636386261643164
          3861363730336331660a316165633232323732633364346636363764623639356562336536636136
          6364