customizing-feature-behavior

name	customizing-feature-behavior
description	Override per-column `sortFn`, `filterFn`, `aggregationFn` and table-level `globalFilterFn` in TanStack Table v9. Covers built-in `filterFns` / `sortFns` / `aggregationFns` registries (passed to `createFilteredRowModel(filterFns)` / `createSortedRowModel(sortFns)` / `createGroupedRowModel(aggregationFns)`), authoring custom functions with the `FilterFn` / `SortFn` / `AggregationFn` signatures, chaining filter→sort via the `addMeta` callback + `row.columnFiltersMeta`, `resolveFilterValue`, `autoRemove`, `invertSorting`, `sortUndefined` ('first'|'last'|-1|1), and `sortDescFirst`. Distinguishes `aggregationFn` (produces value) from `aggregatedCell` (renders value).
type	core
library	tanstack-table
library_version	9.0.0-alpha.48
requires	["state-management"]
sources	["TanStack/table:docs/guide/sorting.md","TanStack/table:docs/guide/column-filtering.md","TanStack/table:docs/guide/fuzzy-filtering.md","TanStack/table:packages/table-core/src/fns/filterFns.ts","TanStack/table:packages/table-core/src/fns/sortFns.ts","TanStack/table:packages/table-core/src/fns/aggregationFns.ts","TanStack/table:examples/react/filters-fuzzy/src/main.tsx"]

This skill builds on tanstack-table/state-management. Read it first for how feature plugins drive state slices.

Setup

v9 customization happens in three places:

1. Built-in function registries — filterFns, sortFns, aggregationFns — passed as arguments to row-model factories so unused fns tree-shake away.
2. Per-column overrides — columnDef.filterFn, columnDef.sortFn, columnDef.aggregationFn (string name OR inline function).
3. Table-level overrides — tableOptions.globalFilterFn.

import {
  tableFeatures,
  rowSortingFeature,
  columnFilteringFeature,
  globalFilteringFeature,
  columnGroupingFeature,
  rowExpandingFeature,
  createFilteredRowModel,
  createSortedRowModel,
  createGroupedRowModel,
  createExpandedRowModel,
  filterFns,
  sortFns,
  aggregationFns,
  createColumnHelper,
} from '@tanstack/table-core'
import type { FilterFn, SortFn, AggregationFn } from '@tanstack/table-core'
import {
  rankItem,
  compareItems,
  type RankingInfo,
} from '@tanstack/match-sorter-utils'

type Person = {
  id: string
  firstName: string
  lastName: string
  revenue: number
  status: 'single' | 'complicated' | 'relationship'
}

const _features = tableFeatures({
  rowSortingFeature,
  columnFilteringFeature,
  globalFilteringFeature,
  columnGroupingFeature,
  rowExpandingFeature,
})

// Module augmentation registers custom fn names so columnDef.filterFn typechecks.
declare module '@tanstack/table-core' {
  interface FilterFns {
    fuzzy: FilterFn<typeof _features, Person>
  }
  interface FilterMeta {
    itemRank?: RankingInfo
  }
}

const fuzzyFilter: FilterFn<typeof _features, Person> = (
  row,
  columnId,
  value,
  addMeta,
) => {
  const itemRank = rankItem(row.getValue(columnId), value)
  addMeta?.({ itemRank })
  return itemRank.passed
}

const columnHelper = createColumnHelper<typeof _features, Person>()

const columns = columnHelper.columns([
  columnHelper.accessor('firstName', {
    filterFn: 'fuzzy', // ← refers to registered name
    sortFn: 'alphanumeric',
  }),
  columnHelper.accessor('revenue', {
    aggregationFn: 'sum',
    aggregatedCell: (info) => `$${info.getValue<number>().toLocaleString()}`,
  }),
])

const table = constructTable({
  _features,
  _rowModels: {
    filteredRowModel: createFilteredRowModel({
      ...filterFns, // keep built-ins
      fuzzy: fuzzyFilter, // add custom
    }),
    sortedRowModel: createSortedRowModel(sortFns),
    groupedRowModel: createGroupedRowModel(aggregationFns),
    expandedRowModel: createExpandedRowModel(),
  },
  columns,
  data,
  globalFilterFn: 'fuzzy',
})

Core Patterns

Pick a built-in sortFn by name + direction control

columnHelper.accessor('lastName', {
  sortFn: 'alphanumeric',
  sortDescFirst: false,
  sortUndefined: 'last', // ABSOLUTE: always at end regardless of asc/desc
})

Layered direction controls:

• sortDescFirst: true/false — first click sorts descending
• sortUndefined: 'first' | 'last' | -1 | 1 | false — string forms are absolute; numeric flips with desc
• invertSorting: true — for "lower-is-better" scales (rank 1 above rank 2 even when descending)

Filter → sort handoff via addMeta

const fuzzyFilter: FilterFn<typeof _features, Person> = (
  row,
  columnId,
  value,
  addMeta,
) => {
  const itemRank = rankItem(row.getValue(columnId), value)
  addMeta?.({ itemRank })
  return itemRank.passed
}

// Custom sortFn reads the meta the filter stashed
const fuzzySort: SortFn<typeof _features, Person> = (rowA, rowB, columnId) => {
  let dir = 0
  if (rowA.columnFiltersMeta[columnId]) {
    dir = compareItems(
      rowA.columnFiltersMeta[columnId].itemRank!,
      rowB.columnFiltersMeta[columnId].itemRank!,
    )
  }
  return dir === 0 ? sortFns.alphanumeric(rowA, rowB, columnId) : dir
}

columnHelper.accessor('fullName', { filterFn: 'fuzzy', sortFn: fuzzySort })

row.columnFiltersMeta is keyed by the column id that produced the meta (or '__global__' for the global filter). The sortFn MUST look up the same column id its filterFn used.

Custom aggregationFn for grouping

import type { AggregationFn } from '@tanstack/table-core'

// Signature: (columnId, leafRows, childRows) → aggregated value
// leafRows = all descendant non-grouped rows
// childRows = immediate children (may be sub-aggregates at deeper levels)
const weightedMean: AggregationFn<typeof _features, Person> = (
  columnId,
  leafRows,
) => {
  let totalWeight = 0
  let weightedSum = 0
  leafRows.forEach((row) => {
    const v = row.getValue<number>(columnId)
    const w = row.original.revenue
    weightedSum += v * w
    totalWeight += w
  })
  return totalWeight === 0 ? 0 : weightedSum / totalWeight
}

const table = constructTable({
  _features,
  _rowModels: {
    groupedRowModel: createGroupedRowModel({ ...aggregationFns, weightedMean }),
    expandedRowModel: createExpandedRowModel(),
  },
  columns: columnHelper.columns([
    columnHelper.accessor('revenue', {
      aggregationFn: 'weightedMean',
      aggregatedCell: (info) => `$${info.getValue<number>().toFixed(2)}`,
    }),
  ]),
  data,
})

Common Mistakes

[CRITICAL] Referencing a custom filterFn by string without registering it

Wrong:

// "fuzzy" string never registered
const table = useTable({
  _features,
  columns: [columnHelper.accessor('fullName', { filterFn: 'fuzzy' })],
  _rowModels: {
    filteredRowModel: createFilteredRowModel(filterFns), // ❌ no fuzzy
  },
  data,
})

Correct:

declare module '@tanstack/react-table' {
  interface FilterFns {
    fuzzy: FilterFn<typeof _features, Person>
  }
}

const fuzzyFilter: FilterFn<typeof _features, Person> = (
  row,
  columnId,
  value,
  addMeta,
) => {
  const itemRank = rankItem(row.getValue(columnId), value)
  addMeta?.({ itemRank })
  return itemRank.passed
}

const table = useTable({
  _features,
  columns: [columnHelper.accessor('fullName', { filterFn: 'fuzzy' })],
  _rowModels: {
    filteredRowModel: createFilteredRowModel({
      ...filterFns,
      fuzzy: fuzzyFilter,
    }),
  },
  data,
})

String values are looked up in table._rowModelFns.filterFns. Unregistered names log Could not find a valid 'column.filterFn' … in dev and silently no-op in prod.

Source: examples/react/filters-fuzzy/src/main.tsx; packages/table-core/src/features/column-filtering/columnFilteringFeature.utils.ts

[HIGH] Using v8 sortingFn / sortingFns names

Wrong:

columnHelper.accessor('age', {
  sortingFn: 'alphanumeric', // v8 name — ignored
})

Correct:

columnHelper.accessor('age', {
  sortFn: 'alphanumeric',
})

v9 renamed every sorting API: sortingFn → sortFn, sortingFns → sortFns, type SortingFn → SortFn, column.getSortingFn() → column.getSortFn(). The default sortFn is 'auto', falling back to sortFn_basic if the lookup misses — so wrong names sort wrong instead of erroring.

Source: docs/framework/react/guide/migrating.md; packages/table-core/src/features/row-sorting/rowSortingFeature.types.ts

[HIGH] Custom sortFn reads filter meta from a different column id

Wrong:

// filter on 'fullName', sort reads meta from 'firstName'
const fuzzySort: SortFn<typeof _features, Person> = (a, b, columnId) => {
  const meta = a.columnFiltersMeta['firstName'] // ❌ wrong key
  return meta
    ? compareItems(meta.itemRank, b.columnFiltersMeta['firstName'].itemRank)
    : 0
}
columnHelper.accessor('fullName', { filterFn: 'fuzzy', sortFn: fuzzySort })

Correct:

const fuzzySort: SortFn<typeof _features, Person> = (rowA, rowB, columnId) => {
  let dir = 0
  if (rowA.columnFiltersMeta[columnId]) {
    dir = compareItems(
      rowA.columnFiltersMeta[columnId].itemRank!,
      rowB.columnFiltersMeta[columnId].itemRank!,
    )
  }
  return dir === 0 ? sortFns.alphanumeric(rowA, rowB, columnId) : dir
}

row.columnFiltersMeta is keyed by the column id that produced it. Always use the columnId argument the sortFn receives.

Source: examples/react/filters-fuzzy/src/main.tsx

[MEDIUM] Returning a complex value from the accessor while using a built-in sortFn

Wrong:

// accessor returns object; alphanumeric sees "[object Object]"
columnHelper.accessor((row) => row.name, {
  id: 'name',
  sortFn: 'alphanumeric',
})

Correct:

// Option A — return a primitive
columnHelper.accessor((row) => `${row.name.first} ${row.name.last}`, {
  id: 'fullName',
  sortFn: 'alphanumeric',
})

// Option B — custom sortFn that knows the shape
columnHelper.accessor((row) => row.name, {
  id: 'name',
  sortFn: (a, b, id) => {
    const av = a.getValue<{ first: string }>(id).first
    const bv = b.getValue<{ first: string }>(id).first
    return av === bv ? 0 : av > bv ? 1 : -1
  },
})

Built-in sortFns (alphanumeric, text, basic) coerce via comparison operators. Object accessors collapse to "[object Object]" and every row ties.

Source: packages/table-core/src/fns/sortFns.ts

[MEDIUM] Confusing aggregationFn with aggregatedCell

Wrong:

// rendering JSX inside the aggregation function
columnHelper.accessor('revenue', {
  aggregationFn: (id, leaves) => <b>${leaves.reduce((a, r) => a + r.getValue(id), 0)}</b>,
})

Correct:

columnHelper.accessor('revenue', {
  aggregationFn: 'sum', // returns a value
  aggregatedCell: (info) => <b>${info.getValue<number>().toLocaleString()}</b>, // renders it
})

aggregationFn produces the grouped-row value (signature (columnId, leafRows, childRows)). aggregatedCell renders it. Don't combine.

Source: packages/table-core/src/features/column-grouping/columnGroupingFeature.types.ts

[CRITICAL] Reimplementing what built-in APIs provide

Wrong:

// Reimplements sorting state manually instead of using the API
const [sorting, setSorting] = useState([])
const sortedData = useMemo(() => [...data].sort(/* … */), [data, sorting])

Correct:

const table = useTable({
  _features: tableFeatures({ rowSortingFeature }),
  _rowModels: { sortedRowModel: createSortedRowModel(sortFns) },
  columns,
  data,
})
// table.setSorting(...), column.toggleSorting(), header.getToggleSortingHandler()

Source: maintainer interview (Phase 4, 2026-05-17)

See also

• tanstack-table/filtering — filterFn placement, fuzzy filter pattern, faceted UI
• tanstack-table/sorting — built-in sortFns, multi-sort, sortUndefined
• tanstack-table/grouping — aggregationFn signature details and built-ins