Numbers and Collections Filters

These filters are the everyday cleanup tools for expression values. Use them when you already have the right data but need to reformat it, count it, sort it, or coerce it into the type another task expects.

abs

Returns the absolute value of a number:

{{ -7 | abs }}
{# output: 7 #}

number

Parses a string into a numeric type. Supports INT, FLOAT, LONG, DOUBLE, BIGDECIMAL, and BIGINTEGER. When no type is specified, the type is inferred:

{{ "12.3" | number | className }}
{# output: java.lang.Float #}
{{ "9223372036854775807" | number('BIGDECIMAL') | className }}
{# output: java.math.BigDecimal #}

Use BIGDECIMAL or BIGINTEGER when values exceed standard long or double precision.

className

Returns the Java class name of an object. Useful for debugging type inference when combined with number:

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

numberFormat

Formats a number using a Java DecimalFormat pattern:

{{ 3.141592653 | numberFormat("#.##") }}
{# output: 3.14 #}

first and last

Returns the first or last element of a collection, or the first or last character of a string:

{{ ['apple', 'banana', 'cherry'] | first }}
{# output: apple #}
{{ ['apple', 'banana', 'cherry'] | last }}
{# output: cherry #}
{{ 'Kestra' | first }}
{# output: K #}
{{ 'Kestra' | last }}
{# output: a #}

length

Returns the number of elements in a collection, or the number of characters in a string:

{{ ['apple', 'banana'] | length }}
{# output: 2 #}
{{ 'Kestra' | length }}
{# output: 6 #}

join

Concatenates a collection into a single string with an optional delimiter:

{{ ['apple', 'banana', 'cherry'] | join(', ') }}
{# output: apple, banana, cherry #}

split

Splits a string into a list using a delimiter. The delimiter is a regex, so escape special characters:

{{ 'apple,banana,cherry' | split(',') }}
{# output: ['apple', 'banana', 'cherry'] #}
{{ 'a.b.c' | split('\\.') }}

The optional limit argument controls how many splits are performed:

• Positive: limits the array size; the last entry contains the remaining content
• Zero: no limit; trailing empty strings are discarded
• Negative: no limit; trailing empty strings are included

{{ 'apple,banana,cherry,grape' | split(',', 2) }}
{# output: ['apple', 'banana,cherry,grape'] #}

sort and rsort

Sort a collection in ascending or descending order:

{{ [3, 1, 2] | sort }}
{# output: [1, 2, 3] #}
{{ [3, 1, 2] | rsort }}
{# output: [3, 2, 1] #}

reverse

Reverses the order of a collection:

{{ [1, 2, 3] | reverse }}
{# output: [3, 2, 1] #}

chunk

Splits a collection into groups of a specified size:

{{ [1, 2, 3, 4, 5] | chunk(2) }}
{# output: [[1, 2], [3, 4], [5]] #}

distinct

Returns only unique values from a collection:

{{ [1, 2, 2, 3, 1] | distinct }}
{# output: [1, 2, 3] #}

slice

Extracts a portion of a collection or string using fromIndex (inclusive) and toIndex (exclusive):

{{ ['apple', 'banana', 'cherry'] | slice(1, 2) }}
{# output: [banana] #}
{{ 'Kestra' | slice(1, 3) }}
{# output: es #}

merge

Merges two collections into one:

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

flatten

Removes one level of nesting from a collection:

{{ [[1, 2], [3, 4], [5]] | flatten }}
{# output: [1, 2, 3, 4, 5] #}

keys and values

Return the keys or values of a map:

{{ {'foo': 'bar', 'baz': 'qux'} | keys }}
{# output: [foo, baz] #}
{{ {'foo': 'bar', 'baz': 'qux'} | values }}
{# output: [bar, qux] #}