[#checklist]
= Input: Checklist

The `checklist` type argument renders multiple checkboxes from predefined `choices`. Users can select one or more options, and the selected values are passed to your action as a comma-separated string.

[source,yaml]
----
actions:
  - title: Backup selected directories
    shell: echo "Backing up: {{ directories }}"
    arguments:
      - name: directories
        title: Directories to back up
        type: checklist
        choices:
          - title: Documents
            value: documents
          - title: Photos
            value: photos
          - title: Music
            value: music
        default: documents,photos
----

When the example above runs with Documents and Photos selected, the shell command becomes:

[source,shell]
----
echo "Backing up: documents,photos"
----

== Select all / Select none

The web interface includes **Select all** and **Select none** controls above the checkbox list.

== Empty selections

If no options are selected, the argument value is an empty string. Use `rejectNull: true` when at least one selection is required.

[source,yaml]
----
arguments:
  - name: directories
    type: checklist
    rejectNull: true
    choices:
      - value: documents
      - value: photos
----

== Choice values

Choice `value` fields must not contain commas, because commas are used to join multiple selections together.

Each `title` is shown in the web interface. If a submitted segment matches a choice `title`, OliveTin maps it to the corresponding `value` before validation, matching the behaviour of xref:args/input_checkbox.adoc[checkbox] arguments with choices.