Why can’t I output Lists from my Sitecore Personalize decision model?

Question

Using a programmable in a Sitecore Personalize decision model, I want to return a List but List is not an available type in the dropdown.

Answer 1

It is not currently possible to output a List from a decision model, in the settings of a programmable ‘List’ is not one of the available output Types in the settings.

If a list is returned from a programmable it will be transformed into a Map as shown below.

List returned as Map from a decision model programmable:

"output": {
        "0": "list1",
        "1": "list2",
        "2": "list3"
    },

If you are using your decision model in a Full Stack experience, you can transform the Map output of your decision model back into a List using FreeMarker.

FreeMarker for transforming decision model Map into List:

{
    "list": [
        <#list MyObject?keys as key>
        "${MyObject[key]}"<#sep>, </#sep>
        </#list>
    ]
}

This FreeMarker snippet can also be seen in the snippets section on the right hand side when building an API Response or Webhook in a Full Stack Experience.

Output from FreeMarker for Transformed List: