Help on typing custom FilterFns

[mgrog]

Hey everyone. This library has been an incredible time saver for me, but I've run against an issue I can't find a great solution for.

In the example for filtering a table what appears to be the recommended way of adding custom FilterFns in typescript is to use a variation of the following code:

declare module '@tanstack/table-core' {
  interface FilterFns {
    fuzzy: FilterFn<unknown>
  }
}

This works well when I have a single react table instance in my code base, but when I have another instance I find the useReactTable hook now globally requires a filterFns option with those same custom filters defined, even when I have no use for those custom filters in another table.

After some searching I have given up and type the custom filter as any in my ColumnDef's to be done with it. This is obviously not ideal for type safety, so I'm wondering has anyone else encountered this issue? Are there any alternatives to declare module for table-core? I've tried looking into the source code but can't find any obvious way of doing it in locally scoped way.

Thanks in advance to all who might help me find a better solution.

[fn0rth]

The problem comes from

table/packages/table-core/src/features/ColumnFiltering.ts

Lines 189 to 195 in ab2819c

	type ResolvedFilterFns = keyof FilterFns extends never
	? {
	filterFns?: Record<string, FilterFn<any>>
	}
	: {
	filterFns: Record<keyof FilterFns, FilterFn<any>>
	}

as soon as we add something to FilterFns it'll be not never and filterFns will be required. I wonder why it is enforced once augmented?

A possible solution is to augment a bit further by overwriting ColumnFiltersOptions

declare module '@tanstack/table-core' {
  interface FilterFns {
    fuzzy: FilterFn<unknown>;
  }
  interface ColumnFiltersOptions<TData extends RowData> {
    filterFns?: Record<string, FilterFn<TData>>;
  }
}