Re: How to encode/decode a class inside a class in JSON

Below comments are on target, I believe. Basically, you:

enable allow_tags.
implement FREEZE and THAW in your class(es) that are being encoded in the JSON
set type in FREEZE with __PACKAGE__ (or something you know)
in __PACKAGE__ implement THAW method that allows you to "inflate" the decoded reference resulting from the JSON

There are a few blind spots in my mind, but they're mostly due to me not trying this out to see what the resulting JSON looks like when FREEZE is invoked and to see how THAW might handle it. Note, these methods are called implicitly when you allow_tags.

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Re^2: How to encode/decode a class inside a class in JSON by tobyink (Canon) on Aug 20, 2020 at 20:51 UTC
When you enable `allow_tags`, the resulting serialization is no longer valid JSON though. toby döt ink	[reply] [d/l]
Re^3: How to encode/decode a class inside a class in JSON by perlfan (Parson) on Aug 21, 2020 at 16:08 UTC
Thanks, that is where I was confused. In that case, you may just be left with adding an internal field `_type` that tracks the intended `__PACKAGE__`. Seems like anything that is done will require some custom coordination between what gets dumped via `TO_JSON` and whatever is used to inflate the instance after an initial `decode`. As I mentioned earlier, I've solved this in the past with a `_type` field that tracked the `__PACKAGE__` name, but the instances were not nested - which in this case complicates it during the decode step. Here's what I suggest: leverage `TO_JSON` during `encode` for all member references; for all include a known internal field that signifies what `__PACKAGE__` it is meant to inflate (e.g., `_type` or `_package` decode JSON (this will give you a reference with no blessed members initially) then use a custom inflator to walk the reference and inflate known members using their section of JSON (you'll either have to assume the package based on key/arraypos or it will carried as an internal field in the JSON) The spirit of this can be described as having the JSON moduling knowing when to call a `FROM_JSON` from the specified package when it sees a special internal field that contains which package to inflate. Since symmetry of this capability is not provided by the JSON module itself, you'll have to implement it yourself as part of the `decode` step.	[reply] [d/l] [select]