JSON functions: Get all keys, check if key exists in JSON, default value in get_variable_value

Question

Functions to: 

 - Check if key exist in JSON object

 - Get all keys in JSON object that can loop with foreach

 - get_variable_value with default value if not exist, so that this would work

http://www.plantuml.com/plantuml/uml/hP5FJuD04CNl-occ4uv8OezBD8MBLwFrZn8EKzXQ57ORTj5MmdTtTzk4zTuJC-_zUCmBAsseDqFNiaLKaw6R4VTMQ8L43hZ46F23Ek6ME_kyRqawskgUQwfcRnLj_OADAC_ewzixGepaT3mSVnrk17LkpN2A0_JXSJsZlJOXclz7dvvVPdJu_WdHzQxHy2MEK2kXGIe3uj1e0uq4LokfLAjwdCgOuMdaC6Bclobg5vIxUTCE0YSsCSOfPOkjwWLLEuXiLHyL-QomE0FWtaxSbK0QJXlfr5dNG5Kbj0QZu5ChoQ68vdkIB8PmpSlpswuLNDs69gXjOFhmvSN2YzafRMyXQrkTyKtALdQs__iF

Answer 1

That's a good idea.

It would help if you could post here some short snippets that would show simple examples.

Something like:

@startuml
!$myjson = {
"name": "Mark McGwire", "hr": 65, "avg":  0.278
}

!foreach $key in %get_json_keys($myjson)
     rectangle $key
!endfor
@enduml

For function names, you can get inspired by other programming languages or library.

Thanks!

Comments

In PHP it has array_key_exists and array_keys

So:

%json_key_exists($data, "theKey")

%json_keys($data, "theKey")

---

Hello all,

Here is an implementation of `json_key_exists` on pure plantuml:

@startuml
!$myjson = {
  "name": "Mark McGwire", "hr": 65, "avg":  0.278
}

!function json_key_exists($myjson, $test)
  !foreach $key in %get_json_keys($myjson)
    !if ($key == $test)
      !return %true()
    !endif
  !endfor
  !return %false()
!end function

:json_key_exists($myjson, "hr");
:json_key_exists($myjson, "foo");
:json_key_exists($myjson, null);
@enduml

Beware of special key... 
See also:

• https://forum.plantuml.net/14930/why-cant-i-compare-json-variable-with-plantuml-boolean

Regards,
Th.

---

Is get_json_keys avaliable in any release?

---

Yes... from V1.2022.1 (1 Feb, 2022)

See:

• https://plantuml.com/changes
• https://forum.plantuml.net/15360/ideas-for-2-new-json-builtins

---

Amazing. I was brothered for hours on figuring out how to check if key exists in PlantUML.

Thank you so much