Link Search Menu Expand Document Documentation Menu
Documentation

subList(, <start_index, inclusive>, <end_index, exclusive>)

The subList() function extracts a sublist from a list field in an event. It takes the following arguments:

  • A JSON pointer to an event field containing a list
  • A start index (inclusive)
  • An end index (exclusive)

The function returns the portion of the list between the specified start and end indexes. If the end index is -1, the function extracts elements from the start index to the end of the list.

Examples

The following examples show how the sublist() function works.

add_entries processor

You can use subList() in the add_entries processor, as shown in the following example.

The function uses the following input to extract a sublist:

input: {"my_list": [ 0, 1, 2, 3, 4, 5, 6]}

Then, the following configuration uses the add_entries processor to extract a sublist from my_list, starting at index 1 and ending before index 4:

add_entries:
  entries:
    - key: "my_list"
      value_expression: '/subList(/my_list, 1, 4)'
      overwrite_if_key_exists: true

The following output shows the resulting list after extracting elements from index 1 to 3 and overwriting the original list:

output: my_list: [1, 2, 3]

Specific ranges

Each of the following examples demonstrates how the subList() function extracts a specific range of elements from a list.

The following example extracts elements from index 0 to 2 (excluding index 3), resulting in the first three elements of the list:

{
  "event": {
    "/my_list": [0, 1, 2, 3, 4, 5, 6]
  },
  "expression": "subList(/my_list, 4, -1)",
  "expected_output": [4, 5, 6]
}

The following example uses -1 as the end index, which specifies to include all elements from index 4 to the end of the list:

{
  "event": {
    "/my_list": [0, 1, 2, 3, 4, 5, 6]
  },
  "expression": "subList(/my_list, 4, -1)",
  "expected_output": [4, 5, 6]
}

350 characters left

Have a question? .

Want to contribute? or .