column-definitions

name	column-definitions
description	Define TanStack Table v9 columns with `createColumnHelper<typeof _features, TData>()`. Covers `columnHelper.accessor` (key + function forms), `columnHelper.display`, `columnHelper.group`, `columnHelper.columns`, the `ColumnDef`/`AccessorKeyColumnDef`/ `AccessorFnColumnDef`/`DisplayColumnDef`/`GroupColumnDef` types, `accessorKey` with `DeepKeys`, `accessorFn`, the `header`/`cell`/`footer`/`aggregatedCell` renderers, required `id` rules, and `getRowId` for stable row identity.
type	core
library	tanstack-table
library_version	9.0.0-alpha.48
sources	["TanStack/table:docs/guide/column-defs.md","TanStack/table:docs/guide/columns.md","TanStack/table:packages/table-core/src/helpers/columnHelper.ts","TanStack/table:packages/table-core/src/core/columns/constructColumn.ts","TanStack/table:examples/react/basic-use-table/src/main.tsx"]

Setup

createColumnHelper takes TWO generics in v9: the features type (so accessor keys, sort/filter strings, etc. are typed against your registered features) and the row data type.

import {
  createColumnHelper,
  tableFeatures,
  rowSortingFeature,
} from '@tanstack/table-core'

type Person = {
  id: string
  firstName: string
  lastName: string
  age: number
  visits: number
}

const _features = tableFeatures({ rowSortingFeature })

// TFeatures FIRST, TData SECOND
const columnHelper = createColumnHelper<typeof _features, Person>()

const columns = columnHelper.columns([
  // accessorKey — deep keys via DeepKeys (dot paths) are supported
  columnHelper.accessor('firstName', { header: 'First Name' }),
  columnHelper.accessor('lastName', { header: 'Last Name' }),
  columnHelper.accessor('age', { header: 'Age' }),

  // accessorFn — needs an explicit `id`
  columnHelper.accessor((row) => `${row.firstName} ${row.lastName}`, {
    id: 'fullName',
    header: 'Full Name',
    cell: (info) => info.getValue(),
  }),

  // display column — no value extraction, just rendering
  columnHelper.display({
    id: 'actions',
    header: 'Actions',
    cell: ({ row }) => `Edit ${row.original.id}`,
  }),

  // group column — wraps child columns under a shared header
  columnHelper.group({
    id: 'stats',
    header: 'Stats',
    columns: [columnHelper.accessor('visits', { header: 'Visits' })],
  }),
])

Core Patterns

Stable row identity with getRowId

const table = useTable({
  _features,
  _rowModels: {},
  columns,
  data,
  getRowId: (row) => row.id, // ← stable from row's own data
})

Without getRowId, row.id defaults to the row's array index. Row-keyed state (selection, expansion, pinning) then attaches to whatever happens to be at that index after a sort/filter/refetch.

Accessor key with deep path

type User = { name: { first: string; last: string } }

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

columnHelper.accessor('name.first', { header: 'First' })
columnHelper.accessor('name.last', { header: 'Last' })

For nested objects with non-optional intermediate keys, the dotted accessorKey form works and infers the right value type. Switch to accessorFn when intermediates are optional (see Common Mistakes below).

Header / cell / footer renderers

columnHelper.accessor('age', {
  header: () => 'Age',
  cell: (info) => info.getValue(),
  footer: (info) => `${info.table.getRowModel().rows.length} rows`,
})

Renderers accept string, JSX (in framework adapters), or function forms. Render via flexRender(def, ctx) or <table.FlexRender header={header} /> so all three forms work uniformly.

columnHelper.columns([...]) for module-scope stability

// Outside any component / hook — stable reference forever
const columns = columnHelper.columns([
  columnHelper.accessor('firstName', { header: 'First' }),
  columnHelper.accessor('lastName', { header: 'Last' }),
])

columnHelper.columns returns the array as-is but preserves the precise tuple types. Hoist to module scope or wrap in useMemo — the table compares columns by reference.

Common Mistakes

[CRITICAL] Passing only TData to createColumnHelper

Wrong:

// v8 signature — TData ends up in the TFeatures slot
const columnHelper = createColumnHelper<Person>()

Correct:

const _features = tableFeatures({ rowSortingFeature })
const columnHelper = createColumnHelper<typeof _features, Person>()

v9 changed the generic order: <TFeatures, TData>. The compiler error is noisy because Person lands in the TFeatures slot and breaks every column type that follows.

Source: packages/table-core/src/helpers/columnHelper.ts; docs/framework/react/guide/migrating.md

[HIGH] Accessor function returns an object or array

Wrong:

// returns an object — built-in alphanumeric sort and includesString filter break
columnHelper.accessor((row) => row.name, {
  id: 'name',
  cell: (info) => `${info.getValue().first} ${info.getValue().last}`,
})

Correct:

// accessor returns a primitive; cell can still format it
columnHelper.accessor((row) => `${row.name.first} ${row.name.last}`, {
  id: 'fullName',
  cell: (info) => info.getValue(),
})

The accessed value drives sorting, filtering, faceting, and grouping. Built-in sortFn/filterFn/aggregationFn expect a primitive string / number / Date. Return a primitive — or supply a matching custom function.

Source: docs/guide/column-defs.md

[CRITICAL] Omitting id on an accessorFn column

Wrong:

// accessorFn + JSX header => no id can be derived
columnHelper.accessor((row) => row.lastName, {
  header: () => <span>Last Name</span>,
  cell: (info) => info.getValue(),
})

Correct:

columnHelper.accessor((row) => row.lastName, {
  id: 'lastName', // required when there's no string accessorKey or string header
  header: () => <span>Last Name</span>,
  cell: (info) => info.getValue(),
})

The constructor throws "coreColumnsFeature require an id when using an accessorFn" in development. The same applies to non-string header values without a fallback id.

Source: packages/table-core/src/core/columns/constructColumn.ts

[CRITICAL] Defining columns inside the component without useMemo

Wrong:

function MyTable() {
  // new array reference every render → infinite render loop
  const columns = [
    columnHelper.accessor('firstName', { header: 'First' }),
    columnHelper.accessor('lastName', { header: 'Last' }),
  ]
  const table = useTable({ _features, _rowModels: {}, columns, data })
}

Correct:

function MyTable() {
  const columns = React.useMemo(
    () =>
      columnHelper.columns([
        columnHelper.accessor('firstName', { header: 'First' }),
        columnHelper.accessor('lastName', { header: 'Last' }),
      ]),
    [],
  )
  const table = useTable({ _features, _rowModels: {}, columns, data })
}

TanStack Table compares columns and data by reference. The #1 FAQ entry across versions.

Source: docs/faq.md; examples/react/basic-subscribe/src/main.tsx

[HIGH] Using array-index row IDs with mutating data

Wrong:

// no getRowId — rowSelection survives data updates but maps to wrong rows
const table = useTable({
  _features,
  _rowModels: {},
  columns,
  data,
  enableRowSelection: true,
})

Correct:

const table = useTable({
  _features,
  _rowModels: {},
  columns,
  data,
  getRowId: (row) => row.id,
  enableRowSelection: true,
})

When data reorders, filters, or items are removed/refetched, row-keyed state (selection, expansion, pinning) attaches to the wrong row.

Source: docs/guide/rows.md; packages/table-core/src/core/rows/coreRowsFeature.utils.ts

[MEDIUM] accessorKey with optional path strips undefined from getValue type

Wrong:

// amount inferred as `number` even though salary is optional
columnHelper.accessor('user.salary.amount', {
  cell: (info) => {
    const amount = info.getValue() // type: number (WRONG)
    return amount.toFixed(2) // crashes when salary is undefined
  },
})

Correct:

columnHelper.accessor((row) => row.user.salary?.amount, {
  id: 'salary',
  cell: (info) => {
    const amount = info.getValue() // type: number | undefined
    return amount?.toFixed(2) ?? '-'
  },
})

The DeepValue type doesn't propagate undefined through optional intermediates. Use accessorFn when any segment is optional — the type follows the expression.

Source: https://github.com/TanStack/table/issues/6238

[MEDIUM] columnHelper.accessor nested inside columnHelper.group loses getValue inference

Wrong:

// info.getValue() inferred as unknown
columnHelper.group({
  id: 'name',
  columns: [
    columnHelper.accessor('firstName', {
      cell: (info) => info.getValue(), // unknown
    }),
  ],
})

Correct:

// Hoist accessor definitions out of the group
const firstNameCol = columnHelper.accessor('firstName', {
  cell: (info) => info.getValue(), // string
})

columnHelper.group({ id: 'name', columns: [firstNameCol] })

The group helper's overloads don't thread TData through correctly when accessors are defined inline.

Source: https://github.com/TanStack/table/issues/5860

See also

• tanstack-table/setup — how _features and _rowModels thread through useTable
• tanstack-table/customizing-feature-behavior — per-column sortFn/filterFn/aggregationFn
• tanstack-table/row-selection — why getRowId is essentially mandatory