flatten()

Recursively traverses nested arrays or collections and flattens all elements into a single-level array.

Syntax

Parameters

ARRAY

The array or collection to flatten.

Description

The flatten() function recursively traverses all nested arrays within the input array and returns the result flattened into a top-level array. If an array contains inner arrays, the elements of those inner arrays are extracted and appended to the top-level array. This process repeats until all nesting is resolved.

If the input is a single value rather than an array or collection, the function returns that value as-is. If the input is null, the function returns null.

Error codes

N/A

Usage examples

1. Flatten a simple nested array

   json "{}" | eval result = flatten(array(1, array(2, 3), 4))
   | # result: [1, 2, 3, 4]
   

2. Flatten an array nested more than two levels deep

   json "{}" | eval result = flatten(array(1, array(2, array(3, 4)), 5))
   | # result: [1, 2, 3, 4, 5]
   

3. null input

   json "{}" | eval result = flatten(null)
   | # result: null
   

Compatibility

flatten() has been available since before Sonar 4.0.