Mantine React Table

Mantine React Table has built-in grouping and aggregation features. There are options for both automatic client-side grouping and aggregation, as well as manual server-side grouping and aggregation. This guide will walk you through the different options and how to use and customize them.

To enable grouping, set the enableGrouping table option to true. This will both add a drag handle button so that columns can be dragged to the dropzone to be grouped and will add an entry column actions menu to group or ungroup a column.

const table = useMantineReactTable({
  columns,
  data,
  enableGrouping: true, //enable grouping
});

const columns = [
  {
    accessorKey: 'name',
    header: 'Name',
    enableGrouping: false, // disable grouping for this column
  },
  {
    accessorKey: 'age',
    header: 'Age',
  },
];

const table = useMantineReactTable({
  columns,
  data,
  enableGrouping: true, //enable grouping
});

return <MantineReactTable table={table} />;

If you do not want the drag buttons that come with the grouping feature, you can independently disable them without disabling the grouping feature entirely by setting the enableColumnDragging table option to false.

const table = useMantineReactTable({
  columns,
  data,
  enableGrouping: true,
  enableColumnDragging: false, //do not show drag handle buttons, but still show grouping options in column actions menu
});

If you want columns to be grouped by default, you can set the grouping state in either the initialState or state table options.

const table = useMantineReactTable({
  columns,
  data,
  enableGrouping: true,
  initialState: { grouping: ['location', 'department'] }, //group by location and department by default
});

In addition to grouping columns by default, you may also want those grouped rows to be expanded and visible by default, too. You can do this by setting the expanded state to true in either the initialState or state table options.

const table = useMantineReactTable({
  columns,
  data,
  enableGrouping: true,
  initialState: {
    grouping: ['location', 'department'], //group by location and department by default and expand grouped rows
    expanded: true, //show grouped rows by default
  },
});

One of the cool features of Mantine React Table is that it can automatically aggregate the data in grouped rows. To enable this, you must specify both an aggregationFn and an AggregatedCell render option on a column definition.

There are several built-in aggregation functions available that you can use. They are:

• count - Finds the number of rows in a group

• extent - Finds the minimum and maximum values of a group of rows

• max - Finds the maximum value of a group of rows

• mean - Finds the average value of a group of rows

• median - Finds the median value of a group of rows

• min - Finds the minimum value of a group of rows

• sum - sums the values of a group of rows

• uniqueCount - Finds the number of unique values of a group of rows

• unique - Finds the unique values of a group of rows

All of these built-in aggregation functions are from TanStack Table

const columns = [
  {
    accessorKey: 'team', //grouped by team in initial state below
    header: 'Team',
  },
  {
    accessorKey: 'player',
    header: 'Player',
  },
  {
    accessorKey: 'points',
    header: 'Points',
    aggregationFn: 'sum', //calc total points for each team by adding up all the points for each player on the team
    AggregatedCell: ({ cell }) => <div>Team Score: {cell.getValue()}</div>,
  },
];

const table = useMantineReactTable({
  columns,
  data,
  enableGrouping: true,
  initialState: { grouping: ['team'], expanded: true },
});

return <MantineReactTable table={table} />;

If none of these pre-built aggregation functions work for you, you can also pass in a custom aggregation function. The aggregation function will be passed in an array of values from the column that you are aggregating. It should return a single value that will be displayed in the aggregated cell.

If you are specifying a custom aggregation function, it must implement the following type:

export type AggregationFn<TData extends AnyData> = (
  getLeafRows: () => Row<TData>[],
  getChildRows: () => Row<TData>[]
) => any

Mantine React Table does not automatically aggregate all rows for you to calculate totals for the entire table. However, it is still easy enough to do this manually and add in your custom calculations into the footer or Footer of a column definition. It is recommended that you do any necessary aggregation calculations on your data in a useMemo hook before passing it to the columns footer in your columns definition.

//calculate the total points for all players in the table in a useMemo hook
const averageScore = useMemo(() => {
  const totalPoints = data.reduce((acc, row) => acc + row.points, 0);
  const totalPlayers = data.length;
  return totalPoints / totalPlayers;
}, [data]);

const columns = [
  {
    accessorKey: 'name',
    header: 'Name',
  },
  {
    accessorKey: 'score',
    header: 'Score',
    Footer: () => <div>Average Score: {averageScore}</div>, //do not do calculations in render, do them in useMemo hook and pass them in here
  },
];

Please remember to perform heavy aggregation calculations in a useMemo hook to avoid unnecessary re-renders!

There are a few custom cell render overrides that you should be aware of when using grouping and aggregation features.

"Aggregation Cells" are cells in an aggregated row (not a normal data row) that can display aggregates (avg, sum, etc.) of the data in a group. The cell that the table is grouped on, however, is not an Aggregate Cell, but rather a GroupedCell.

You can specify the custom render for these cells with the AggregatedCell render option on a column definition.

const columns = [
  {
    accessorKey: 'points',
    header: 'Points',
    aggregationFn: 'sum',
    AggregatedCell: ({ cell }) => <div>Total Score: {cell.getValue()}</div>,
  },
];

"Grouped Cells" are cells in a grouped row (not a normal data row) that by default display the value that the rows are grouped on and the number of rows in the group. You can override the default render for these cells with the GroupedCell render option on a column definition.

const columns = [
  {
    accessorKey: 'team',
    header: 'Team',
    GroupedCell: ({ cell }) => <div>Team: {cell.getValue()}</div>,
  },
];

"Placeholder Cells" are cells that are usually meant to be empty in grouped rows and columns. They are simply rendered with a value of null by default, but you can override the default render for these cells with the PlaceholderCell render option on a column definition.

const columns = [
  {
    accessorKey: 'team',
    header: 'Team',
    PlaceholderCell: ({ cell, row }) => (
      <div>{row.original.someOtherRowValue}</div>
    ),
  },
];

import '@mantine/core/styles.css';
import '@mantine/dates/styles.css'; //if using mantine date picker features
import 'mantine-react-table/styles.css'; //make sure MRT styles were imported in your app root (once)
import { useMemo } from 'react';
import { Box, Stack } from '@mantine/core';
import {
  MantineReactTable,
  useMantineReactTable,
  type MRT_ColumnDef,
} from 'mantine-react-table';
import { data, type Person } from './makeData';

const Example = () => {
  const averageSalary = useMemo(
    () => data.reduce((acc, curr) => acc + curr.salary, 0) / data.length,
    [],
  );

  const maxAge = useMemo(
    () => data.reduce((acc, curr) => Math.max(acc, curr.age), 0),
    [],
  );

  const columns = useMemo<MRT_ColumnDef<Person>[]>(
    () => [
      {
        header: 'First Name',
        accessorKey: 'firstName',
        enableGrouping: false, //do not let this column be grouped
      },
      {
        header: 'Last Name',
        accessorKey: 'lastName',
      },
      {
        header: 'Age',
        accessorKey: 'age',
        aggregationFn: 'max', //show the max age in the group (lots of pre-built aggregationFns to choose from)
        //required to render an aggregated cell
        AggregatedCell: ({ cell, table }) => (
          <>
            Oldest by{' '}
            {table.getColumn(cell.row.groupingColumnId ?? '').columnDef.header}:{' '}
            <Box
              style={{
                color: 'skyblue',
                display: 'inline',
                fontWeight: 'bold',
              }}
            >
              {cell.getValue<number>()}
            </Box>
          </>
        ),
        Footer: () => (
          <Stack>
            Max Age:
            <Box color="orange">{Math.round(maxAge)}</Box>
          </Stack>
        ),
      },
      {
        header: 'Gender',
        accessorKey: 'gender',
        //optionally, customize the cell render when this column is grouped. Make the text blue and pluralize the word
        GroupedCell: ({ cell, row }) => (
          <Box style={{ color: 'skyblue' }}>
            <strong>{cell.getValue<string>()}s </strong> ({row.subRows?.length})
          </Box>
        ),
      },
      {
        header: 'State',
        accessorKey: 'state',
      },
      {
        header: 'Salary',
        accessorKey: 'salary',
        aggregationFn: 'mean',
        //required to render an aggregated cell, show the average salary in the group
        AggregatedCell: ({ cell, table }) => (
          <>
            Average by{' '}
            {table.getColumn(cell.row.groupingColumnId ?? '').columnDef.header}:{' '}
            <Box style={{ color: 'green', fontWeight: 'bold' }}>
              {cell.getValue<number>()?.toLocaleString?.('en-US', {
                style: 'currency',
                currency: 'USD',
                minimumFractionDigits: 0,
                maximumFractionDigits: 0,
              })}
            </Box>
          </>
        ),
        //customize normal cell render on normal non-aggregated rows
        Cell: ({ cell }) => (
          <>
            {cell.getValue<number>()?.toLocaleString?.('en-US', {
              style: 'currency',
              currency: 'USD',
              minimumFractionDigits: 0,
              maximumFractionDigits: 0,
            })}
          </>
        ),
        Footer: () => (
          <Stack>
            Average Salary:
            <Box color="orange">
              {averageSalary?.toLocaleString?.('en-US', {
                style: 'currency',
                currency: 'USD',
                minimumFractionDigits: 0,
                maximumFractionDigits: 0,
              })}
            </Box>
          </Stack>
        ),
      },
    ],
    [averageSalary, maxAge],
  );

  const table = useMantineReactTable({
    columns,
    data,
    enableColumnResizing: true,
    enableGrouping: true,
    enableStickyHeader: true,
    enableStickyFooter: true,
    initialState: {
      density: 'xs',
      expanded: true,
      grouping: ['state'],
      pagination: { pageIndex: 0, pageSize: 20 },
      sorting: [{ id: 'state', desc: false }],
    },
    mantineToolbarAlertBannerBadgeProps: { color: 'blue', variant: 'outline' },
    mantineTableContainerProps: { style: { maxHeight: 700 } },
  });

  return <MantineReactTable table={table} />;
};

export default Example;

You may want to calculate more than one aggregation per column. If so, you can specify an array of aggregationFns, and then reference the aggregation results from an array in the AggregatedCell render option.

const columns = [
  {
    header: 'Salary',
    accessorKey: 'salary',
    aggregationFn: ['count', 'mean'], //multiple aggregation functions
    AggregatedCell: ({ cell, table }) => (
      <div>
        {/*get the count from the first aggregation*/}
        <div>Count: {cell.getValue()[0]}</div>
        {/*get the average from the second aggregation*/}
        <div>Average Salary: {cell.getValue()[1]}</div>
      </div>
    ),
  },
];

import '@mantine/core/styles.css';
import '@mantine/dates/styles.css'; //if using mantine date picker features
import 'mantine-react-table/styles.css'; //make sure MRT styles were imported in your app root (once)
import { useMemo } from 'react';
import { Box } from '@mantine/core';
import { MantineReactTable, type MRT_ColumnDef } from 'mantine-react-table';
import { data, type Person } from './makeData';

const localeStringOptions = {
  style: 'currency',
  currency: 'USD',
  minimumFractionDigits: 0,
  maximumFractionDigits: 0,
} as const;

const Example = () => {
  const columns = useMemo<MRT_ColumnDef<Person>[]>(
    () => [
      {
        header: 'First Name',
        accessorKey: 'firstName',
      },
      {
        header: 'Last Name',
        accessorKey: 'lastName',
      },
      {
        header: 'Gender',
        accessorKey: 'gender',
      },
      {
        header: 'State',
        accessorKey: 'state',
      },
      {
        header: 'Salary',
        accessorKey: 'salary',
        aggregationFn: ['count', 'mean', 'median', 'min', 'max'],
        //required to render an aggregated cell, show the average salary in the group
        AggregatedCell: ({ cell }) => (
          <>
            Count:{' '}
            <Box style={{ color: 'green', fontWeight: 'bold' }}>
              {cell.getValue<Array<number>>()?.[0]}
            </Box>
            Average:{' '}
            <Box style={{ color: 'green', fontWeight: 'bold' }}>
              {cell
                .getValue<Array<number>>()?.[1]
                ?.toLocaleString?.('en-US', localeStringOptions)}
            </Box>
            Median:{' '}
            <Box style={{ color: 'green', fontWeight: 'bold' }}>
              {cell
                .getValue<Array<number>>()?.[2]
                ?.toLocaleString?.('en-US', localeStringOptions)}
            </Box>
            Min:{' '}
            <Box style={{ color: 'green', fontWeight: 'bold' }}>
              {cell
                .getValue<Array<number>>()?.[3]
                ?.toLocaleString?.('en-US', localeStringOptions)}
            </Box>
            Max:{' '}
            <Box style={{ color: 'green', fontWeight: 'bold' }}>
              {cell
                .getValue<Array<number>>()?.[4]
                ?.toLocaleString?.('en-US', localeStringOptions)}
            </Box>
          </>
        ),
        //customize normal cell render on normal non-aggregated rows
        Cell: ({ cell }) => (
          <>
            {cell
              .getValue<number>()
              ?.toLocaleString?.('en-US', localeStringOptions)}
          </>
        ),
      },
    ],
    [],
  );

  return (
    <MantineReactTable
      columns={columns}
      data={data}
      enableGrouping
      enableStickyHeader
      initialState={{
        density: 'xs',
        expanded: true, //expand all groups by default
        grouping: ['state', 'gender'], //an array of columns to group by by default (can be multiple)
        pagination: { pageIndex: 0, pageSize: 20 },
        sorting: [{ id: 'state', desc: false }], //sort by state by default
      }}
      mantineToolbarAlertBannerBadgeProps={{ color: 'primary' }}
      mantineTableContainerProps={{ style: { maxHeight: 700 } }}
    />
  );
};

export default Example;

Manual Grouping means that the data that you pass to the table is already grouped and aggregated, and you do not want Mantine React Table to do any of the grouping or aggregation for you. This is useful if you are using a backend API to do the grouping and aggregation for you, and you just want to display the results. However, you will need to put your data in the specific format that the expanding features understand.