Can I dynamically set reference lookup logic in a Transform Map (instead of static Choice Action)?

[EdanR]

I’m working on a ServiceNow Transform Map where a source field maps to a reference field on the target table (e.g., company → core_company). The target table includes both customers (customer=true) and vendors (vendor=true), but I only want to link vendor-type companies during the import.

Currently, the Choice Action setting on the field map is static and doesn’t allow row-level logic. My question:

• Is there a way to dynamically control which record gets linked (or skip linking) based on attributes of the target record (e.g., vendor=true)?
• Can this be done via a Source script on the field map, or is there another recommended approach?

Goal: Prevent accidental linking to a customer-type company when importing vendor data.

Any best practices or examples for implementing this logic would be appreciated!

[Ankur Bawiskar]

@EdanR 

don't use Field map script.

Handle this logic using onBefore transform script

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[Ankur Bawiskar · Accepted solution]

@EdanR 

using field map script is also possible

something like this and it will pick only vendor=true company record

answer = (function transformEntry(source) {

    var companyName = source.company_value; // Adjust field name as needed
    if (!companyName) {
        return -1; 
    }

    // Lookup ONLY vendor companies
    var gr = new GlideRecord('core_company');
    gr.addQuery('name', companyName); // Or your lookup field: 'u_vendor_code', etc.
    gr.addQuery('vendor', true);
    gr.query();
    if (gr.next()) {
        return gr.sys_id.toString(); // Link this vendor
    }

    return '';

})(source);

💡 If my response helped, please mark it as correct ✅ and close the thread 🔒— this helps future readers find the solution faster! 🙏