column formatting with json for lookup fields

Question

I have problems formatting the column of a lookup field with json. Precisely, it is an additional field, displayed from the parent list that I want to format. The lookup field is of type multiple, so I want to loop over all items with forEach.

For reference, this code works on the primary lookup column as a MVP.

 {
      "$schema": "https://developer.microsoft.com/json-schemas/sp/column-formatting.schema.json",
      "elmType": "div",
      "children": [
        {
          "forEach": "choiceIterator in @currentField",
          "elmType": "div",
          "txtContent": "[$choiceIterator.lookupValue]"
        }
      ]
    }

When I use this code on the "additional" column, the column entries are empty. The sharepoint default for this additional column is a semicolon separeted list of all items which I do not like.

Answer 1

Unfortunately, after looking into this further, you won't be able to properly work with mulit-value projected fields at this time. While the primary lookup value comes back as an array of objects with the lookupId and lookupValue properties, the projected fields come back as a single string with the semi-colon already inserted. This is super frustrating.

If you use your format above and add the "debugMode":true to the format you'll see the message about this field not being an array (which is required for using the forEach property):

Without the addition of a split operator, or at the very least a substring operator, there is no real way to work with these types of values (at least right now).