Munawirrahman has posted a useful new Flow Action package that takes a different, looser, more dynamic approach to getting data out of JSON for use in Flow. His action invites the user to simply list out the interesting keys, and he returns the extracted values. His approach allows for full penetration of nested data.
UPDATE: Also see this additional post.
He points to a blog post we missed, from Rafael Cunha, that discusses the use of Apex-Defined Types to handle incoming JSON….
in the style of the original Apex-Defined Type article here:
The use of Apex-Defined Types is great when you’re building your own Flow Action. It allows you to permanently provide a conversion bridge from the JSON to Flow data structures in a way that your users running your flow will never have to think about. But if you instead are dealing with different kind of JSON, a dynamic extractor like the one Munawirrahman provides is an excellent tool.