Custom sortingFn not applying with sortUndefined: 'last' config

[LaurentFacente]

material-react-table version

2.13.1

react & react-dom versions

18.2.0

Describe the bug and the steps to reproduce it

Custom sortingFn not applying with sortUndefined: 'last' config

Issue Description

I'm having an issue with a custom sorting function in TanStack Table (Material React Table). I've created a custom sort function to treat zero values as undefined and sort them last, but it's not working as expected when combined with sortUndefined: 'last'.

Reproduction Steps

1. Created a custom sort function called mapZeroToUndefinedSort
2. Registered it in table config under sortingFns
3. Applied it to a column with sortUndefined: 'last'
4. Zero values are not being sorted to the end as expected

Expected Behavior

• When column is sorted, values of 0 should be treated as undefined
• These undefined (0) values should be sorted to the end with sortUndefined: 'last'

Actual Behavior

• Zero values appear mixed in with other values
• The sortUndefined: 'last' setting doesn't seem to apply to zero values mapped to undefined

Question

Is there something wrong with my approach? Should I be handling the undefined sorting completely within my custom sort function instead of relying on sortUndefined: 'last'? Any guidance would be appreciated!

Minimal, Reproducible Example - (Optional, but Recommended)

My Implementation

Custom Sort Function:

// common/utils/customTableSort.utils.ts
import { SortingFn } from '@tanstack/react-table';

export const mapZeroToUndefinedSort: SortingFn<unknown> = (rowA, rowB, columnId) => {
  const a = rowA.getValue<number | null | undefined>(columnId);
  const b = rowB.getValue<number | null | undefined>(columnId);

  // Map 0 to undefined so sortUndefined:'last' can handle it
  const effectiveA = a === 0 ? undefined : a;
  const effectiveB = b === 0 ? undefined : b;

  // If both are non-undefined (and non-zero), perform standard numeric comparison
  // Also handle potential nulls as smallest
  if (effectiveA !== undefined && effectiveB !== undefined) {
    const valA = effectiveA ?? -Infinity;
    const valB = effectiveB ?? -Infinity;
    return valA - valB;
  }

  // If one or both are undefined (originally 0 or actually undefined/null),
  // return 0. The sortUndefined logic should handle them.
  return 0;
};

Column Definition:

{
  accessorKey: `data.${selectedYear}.eac`,
  header: 'EAC',
  sortingFn: 'mapZeroToUndefinedSort',
  sortUndefined: 'last',
  // other properties...
}

Table Configuration:

const [table, { /* ... */ }] = useTableWithDefaultSettings({
  // other config...
  sortingFns: {
    mapZeroToUndefinedSort,
  },
  // more config...
});

Screenshots or Videos (Optional)

No response

Do you intend to try to help solve this bug with your own PR?

None

Terms

• I understand that if my bug cannot be reliably reproduced in a debuggable environment, it will probably not be fixed and this issue may even be closed.