Cant do nested for loop unless used within new array context.

[samer1977]

Hi,
Sometimes I find myself traversing different level arrays where Im interested at certain array level data. let's say we have the following json:

{
	"root": [
		{
			"batch_0": [
				{
					"end": "20240101",
					"start": "20240101",
					"id": "ABC10XX0092001"
				},
				{
					"end": "20230101",
					"start": "20230101",
					"id": "ABC10XX0092000"
				}
			],
			"batch_1": [
				{
					"end": "20220101",
					"start": "20220101",
					"id": "ABC10XX00920"
				}
			]
		}
	]
}

If I want to bucket all id values into an array in new json as follows:

{
  "ids" : [ "ABC10XX0092001", "ABC10XX0092000", "ABC10XX00920" ]
}

Obviously I have to do nested for loop here (unless Im missing something) but the only way I can do nested loop is by declaring an new array for each for and then do flattening of all nested arrays to become one:

{

  "ids":flatten([for(.root) [for(.) [for(.value) .id]]])
}

Why I cant do direct nested of for loop as follows:

{

  "ids":[for(.root) 
                  for(.)
                        for(.value) .id ]
}

I tried to use Pipe operator as well , and it did not work. It always complain about two consecutive for statement. Can this be an enchantment to save overhead , get better performance and make the code more readable or this can cause other issues ?

Thanks