The Payload is an Object and NOT an Array.
Does that mean that “Create Record” is only used to create one parent record per Request?
When you want to create one parent record with associated child records, it would seem that doing it with a single call would be the most efficient (rather than creating the parent record and the related child records as separate calls. Is that true?
When you want to create more than one parent record with associated child records, is the best practice to Post one by one, or to send a JSON Array and process the Array with a script and script.param?
#2: depends on your definition of "most efficient", what's the efficiency you have in mind? Minimizing the # of calls to the API? Speed?
#3: best practice? No. Because it depends immensely on whether your server can handle the scripting engine load you want to put on it. By invoking the DAPI script engine you're adding one more session to the server in addition to the pure DAPI session.
Plus it delays the response to the caller which usually is a big no-no in the world of calling APIs, you don't want to block the calling thread for that long.
does portalData require a portal or would any related field do? No Portal Required
can you write to more than one portal? Yes
if you need a transactional approach, would you create a transaction record with portals to everything you need to create at the same time, or do you need to put something together using the modId?
Sorry for being lazy and not looking up the official documentation first, but I suspect it won't say much about transactions.
Ended up looking at FileMaker 19 Data API Guide and choose to answer some myself, please correct me if I am wrong.