​Object ​Filters (​Maps, ​Arrays and ​More)

Object filters help you manipulate maps and arrays.

Each section below represents a built-in filter.

• chunk
• className
• first
• join
• keys
• last
• merge
• reverse
• rsort
• slice
• sort
• split

chunk

The chunk filter returns partitions of size from a list.

{{ [[1,2,3,4,5,6,7,8,9]] | chunk(2) }}
{# results in: '[[1,2],[3,4],[5,6],[7,8],[9]]' #}

Arguments

• size: the size of the chunk

className

The className filter return a string with the current class name.

{{ "12.3" | number | className }}
{# will output: java.lang.Float #}

first

The first filter will return the first item of a collection, or the first letter of a string.

{{ users | first }}
{# will output the first item in the collection named 'users' #}

{{ 'Mitch' | first }}
{# will output 'M' #}

join

The join filter will concatenate all items of a collection into a string. An optional argument can be given to be used as the separator between items.

{#
    List<String> names = new ArrayList<>();
    names.add("Alex");
    names.add("Joe");
    names.add("Bob");
#}
{{ names | join(',') }}
{# will output: Alex,Joe,Bob #}

Arguments

• separator

keys

The keys filter will return the keys from a collection, or list of index of an array.

{{ {'this': 'foo', 'that': 'bar'} | keys }}
{# will output the keys from this map '['this', 'that']' #}


{{ [0, 1, 3] | keys }}
{# will output the key from this array '[0, 1, 2]' #}

values

The values filter will return the values from a map:

{{ {'this': 'foo', 'that': 'bar'} | values }}
{# will output the values from this map '['foo', 'bar']' #}

Here is how you can test that expression in a flow:

id: expression
namespace: company.myteam
tasks:
  - id: hello
    type: io.kestra.plugin.core.log.Log
    message: "{{ {'this': 'foo', 'that': 'bar'} | values }}"

last

The last filter will return the last item of a collection, or the last letter of a string.

{{ users | last }}
{# will output the last item in the collection named 'users' #}

{{ 'Mitch' | last }}
{# will output 'h' #}
```## length

The `length` filter returns the number of items of collection, map or the length of a string:

```twig
{% if users | length > 10 %}
    ...
{% endif %}

merge

The merge filter merge items of type Map, List or Array:

{{ [1, 2] | merge([3, 4]) }}

reverse

The reverse filter reverses a List:

{% for user in users | reverse %} {{ user }} {% endfor %}

rsort

The rsort filter will sort a list in reversed order. The items of the list must implement Comparable.

{% for user in users | rsort %}
    {{ user.name }}
{% endfor %}

slice

The slice filter returns a portion of a list, array, or string.

{{ ['apple', 'peach', 'pear', 'banana'] | slice(1,3) }}
{# results in: [peach, pear] #}


{{ 'Mitchell' | slice(1,3) }}
{# results in: 'it' #}

Arguments

• fromIndex: 0-based and inclusive
• toIndex: 0-based and exclusive

sort

The sort filter will sort a list. The items of the list must implement Comparable.

{% for user in users | sort %}
    {{ user.name }}
{% endfor %}

split

The split filter splits a string by the given delimiter and returns a list of strings.

{% set foo = "one,two,three" | split(',') %}
{# foo contains ['one', 'two', 'three'] #}

You can also pass a limit argument:

• If limit is positive, then the pattern will be applied at most n - 1 times, the array's length will be no greater than n, and the array's last entry will contain all input beyond the last matched delimiter;
• If limit is negative, then the pattern will be applied as many times as possible and the array can have any length;
• If limit is zero, then the pattern will be applied as many times as possible, the array can have any length, and trailing empty strings will be discarded;

{% set foo = "one,two,three,four,five" | split(',', 3) %}
{# foo contains ['one', 'two', 'three,four,five'] #}

Arguments

• delimiter: The delimiter
• limit: The limit argument