Classification set replacement with LOADRECORDS

Overview

Fulcrum's built-in Classification Set field only returns a single hierarchy of values. When you need to capture multiple attributes (e.g. building + component + sub-component) from a lookup table, you can replicate the drill-down experience using a linked app as the data source and LOADRECORDS + SETCHOICES to build cascading choice fields dynamically.

How it works:

A separate "lookup" app holds every valid combination as individual records (e.g. each record has a building, component, and sub_component field).
On load-record, all records from the lookup app are fetched into memory.
A choice field for the first level (building) is populated with unique values from the lookup set.
As the user selects each level, the next level's choices are filtered down to only the values that match the current selection.
The final selection can then auto-populate other fields in the record (cost codes, specs, etc.) via additional ON('change', ...) handlers.

This pattern works entirely offline after the initial load, since LOADRECORDS caches the result set.

Configuration

Replace the following values before deploying:

Constant	Description
`LOOKUP_FORM_ID`	The form ID of your lookup / reference app
`'building'`	The `data_name` of the first-level choice field
`'component_choice'`	The `data_name` of the second-level choice field
`'3150'`	The field key in the lookup app for the first-level attribute
`'1aba'`	The field key in the lookup app for the second-level attribute

Finding field keys: In your lookup app's Data Events editor, run ALERT(INSPECT(result.records[0].form_values)) inside the LOADRECORDS callback to see all field keys and their current values.

Code

// ─── CONFIGURATION ───────────────────────────────────────────────────────────
const LOOKUP_FORM_ID       = 'YOUR-LOOKUP-FORM-ID';
const LEVEL1_FIELD        = 'building';           // data_name of first choice field
const LEVEL2_FIELD        = 'component_choice';   // data_name of second choice field
const LEVEL1_KEY          = '3150';               // field key in lookup app for level 1
const LEVEL2_KEY          = '1aba';               // field key in lookup app for level 2
// If you add a third level (see "Extending to more levels" below), also define:
//   const LEVEL3_FIELD = 'sub_component_choice';  // data_name of third choice field
//   const LEVEL3_KEY   = 'YOUR-LEVEL-3-FIELD-KEY'; // field key in lookup app for level 3
// ─────────────────────────────────────────────────────────────────────────────

let lookupRecords = [];

ON('load-record', () => {
  LOADRECORDS({ form_id: LOOKUP_FORM_ID }, (err, result) => {
    if (err) {
      ALERT(INSPECT(err));
      return;
    }

    lookupRecords = result.records;

    // Build unique list of level-1 values and populate the first choice field
    const level1Values = lookupRecords
      .map(r => CHOICEVALUE(r.form_values[LEVEL1_KEY]))
      .filter(onlyUnique);

    // SETCHOICES accepts an array of strings (label and value are the same).
    // Use [{ label, value }] objects instead if you need a different stored value.
    SETCHOICES(LEVEL1_FIELD, level1Values);
  });
});

ON('change', LEVEL1_FIELD, () => {
  // Lookup records may not have loaded yet (or the load may have failed)
  if (ISBLANK(VALUE(LEVEL1_FIELD)) || lookupRecords.length === 0) return;

  // Filter lookup records to those matching the current level-1 selection
  const level2Values = lookupRecords
    .filter(r => CHOICEVALUE(r.form_values[LEVEL1_KEY]) === CHOICEVALUE(VALUE(LEVEL1_FIELD)))
    .map(r => CHOICEVALUE(r.form_values[LEVEL2_KEY]))
    .filter(onlyUnique);

  SETCHOICES(LEVEL2_FIELD, level2Values);
});

// ─── UTILITIES ───────────────────────────────────────────────────────────────

function onlyUnique(value, index, array) {
  return array.indexOf(value) === index;
}

Extending to more levels

Add additional ON('change', ...) handlers for each subsequent level, filtering lookupRecords further on each step. Each handler re-filters the full lookupRecords array using all selections made so far:

ON('change', LEVEL2_FIELD, () => {
  if (ISBLANK(VALUE(LEVEL2_FIELD))) return;

  const level3Values = lookupRecords
    .filter(r =>
      CHOICEVALUE(r.form_values[LEVEL1_KEY]) === CHOICEVALUE(VALUE(LEVEL1_FIELD)) &&
      CHOICEVALUE(r.form_values[LEVEL2_KEY]) === CHOICEVALUE(VALUE(LEVEL2_FIELD))
    )
    .map(r => CHOICEVALUE(r.form_values[LEVEL3_KEY]))
    .filter(onlyUnique);

  SETCHOICES(LEVEL3_FIELD, level3Values);
});

Notes

LOADRECORDS returns up to 20,000 records. For very large lookup tables, consider pre-filtering with a form_values query parameter.
The lookup app can be hidden from end users using project or role restrictions — it only needs to be accessible to the data event context.
To also auto-populate non-choice fields on final selection (e.g. cost code, description), add a handler on the last level field that finds the matching lookup record and calls SETVALUE() for each field.