Expanding Sub-Rows/Tree Data Guide - Material React Table V3 Docs

Expanding Sub-Rows (Tree Data) Feature Guide

Material React Table has support for expanding sub-rows or tree data. This feature is useful for displaying hierarchical data. The sub-rows can be expanded and collapsed by clicking on the expand/collapse icon.

NOTE: This feature is for expanding rows of the same data type. If you want to add expansion of more data for the same row, check out the Detail Panel Feature Guide.

Relevant Table Options

#	Type	Default Value	More Info Links
1	boolean		TanStack Table Expanding Docs

2	Array<TData>		Usage Docs

3	boolean	true	MRT Expanding Sub Rows Docs

4	boolean		MRT Expanding Sub Rows Docs

5	(dataRow: TData) => TData[]

6	boolean	false	TanStack Filtering Docs

7	() => MRT_RowModel<TData>

8	(row: Row<TData>) => boolean		TanStack Table Expanding Docs

9	(row: Row<TData>) => boolean		TanStack Table Expanding Docs

10	(originalRow: TData, index: number, parent?: MRT_Row<TData>) => string		TanStack Table Core Table Docs

11	(originalRow: TData, index: number) => undefined \| TData[]		TanStack Table Core Table Docs

12	false \| 'reorder' \| 'remove'	reorder	TanStack Table Grouping Docs

13	boolean		TanStack Table Expanding Docs

14	number	100	TanStack Table Filtering Docs

15	IconButtonProps \| ({ table }) => IconButtonProps		Material UI IconButton Props

16	IconButtonProps \| ({ row, table }) => IconButtonProps		Material UI IconButton Props

17	OnChangeFn<ExpandedState>		TanStack Table Expanding Docs

18	boolean		TanStack Table Expanding Docs

19	'first' \| 'last'	'first'

Relevant State Options

	#	State Option	Type	Default Value	More Info Links
	1		Record<string, boolean> \| boolean	{}	TanStack Table Expanding Docs

Enable Expanding Sub-Rows

To enable expanding sub-rows, you must first set the enableExpanding table option to true.

However, your data must also be formatted in a way to allow for expanding rows that are in some way related to each other. By default, Material React Table will look for a special subRows property on each row of your data and treat any array of rows that it finds as the sub-rows for that row. You can customize or override this behavior by passing a custom getSubRows table option.

const data = [
  {
    id: 1,
    name: 'John Doe',
    subRows: [
      {
        id: 2,
        name: 'Jane Doe',
      },
      //more sub rows...
    ],
  },
  //more rows...
];

const table = useMaterialReactTable({
  columns,
  data,
  enableExpanding: true,
  getSubRows: (originalRow) => originalRow.subRows, //default, can customize
});

return <MaterialReactTable table={table} />;

Expand All Rows Button

By default, Material React Table will show the expand all button in the expand column header. You can disable this by setting the enableExpandAll table option to false.

const table = useMaterialReactTable({
  columns,
  data,
  enableExpanding: true,
  enableExpandAll: false, //hide expand all button in header
});

Demo

Open Stackblitz Open Code Sandbox Open on GitHub

Primary

Secondary

Drop to group by

Expand	First Name	Last Name	Address	City	State
	Dylan	Murray	261 Erdman Ford	East Daphne	Kentucky
	Raquel	Kohler	769 Dominic Grove	Columbus	Ohio

Rows per page

1-2 of 2

This example is written for MRT V3.

If your app is still using MRT V1, either Upgrade to MRT V3 or use the V1 Docs instead. (useMaterialReactTable only exists in V2 and V3)

Source Code

1import { useMemo } from 'react';
2import {
3  MaterialReactTable,
4  useMaterialReactTable,
5  type MRT_ColumnDef,
6} from 'material-react-table';
7
8export type Person = {
9  firstName: string;
10  lastName: string;
11  address: string;
12  city: string;
13  state: string;
14  subRows?: Person[]; //Each person can have sub rows of more people
15};
16
17export const data = [
18  {
19    firstName: 'Dylan',
20    lastName: 'Murray',
21    address: '261 Erdman Ford',
22    city: 'East Daphne',
23    state: 'Kentucky',
24    subRows: [
25      {
26        firstName: 'Ervin',
27        lastName: 'Reinger',
28        address: '566 Brakus Inlet',
29        city: 'South Linda',
30        state: 'West Virginia',
31        subRows: [
32          {
33            firstName: 'Jordane',
34            lastName: 'Homenick',
35            address: '1234 Brakus Inlet',
36            city: 'South Linda',
37            state: 'West Virginia',
38          },
39        ],
40      },
41      {
42        firstName: 'Brittany',
43        lastName: 'McCullough',
44        address: '722 Emie Stream',
45        city: 'Lincoln',
46        state: 'Nebraska',
47      },
48    ],
49  },
50  {
51    firstName: 'Raquel',
52    lastName: 'Kohler',
53    address: '769 Dominic Grove',
54    city: 'Columbus',
55    state: 'Ohio',
56    subRows: [
57      {
58        firstName: 'Branson',
59        lastName: 'Frami',
60        address: '32188 Larkin Turnpike',
61        city: 'Charleston',
62        state: 'South Carolina',
63      },
64    ],
65  },
66];
67
68const Example = () => {
69  const columns = useMemo<MRT_ColumnDef<Person>[]>(
70    //column definitions...
71    () => [
72      {
73        accessorKey: 'firstName',
74        header: 'First Name',
75      },
76      {
77        accessorKey: 'lastName',
78        header: 'Last Name',
79      },
80
81      {
82        accessorKey: 'address',
83        header: 'Address',
84      },
85      {
86        accessorKey: 'city',
87        header: 'City',
88      },
89
90      {
91        accessorKey: 'state',
92        enableColumnOrdering: false,
93        header: 'State',
94      },
95    ],
96    [],
97    
98  );
99
100  const table = useMaterialReactTable({
101    columns,
102    data,
103    enableExpandAll: false, //hide expand all double arrow in column header
104    enableExpanding: true,
105  });
106
107  return <MaterialReactTable table={table} />;
108};
109
110export default Example;
111

Generate Sub Rows with getSubRows

If your data is not yet in a tree structure, but the data has relationships that can be parsed into a tree, you can use the getSubRows table option to let TanStack Table find the sub rows for each row.

There are a couple key things you have to do to make this work:

Only pass in root (top level) rows in your data prop.
Set the getSubRows table option to a function that scans all the rest of your data and returns the sub rows for a given row.

This can sometimes be useful in combination with lazy loading sub rows.

NOTE: Be conscious of the performance implications of the getSubRows function. It will be called for every row in your table, so it should be performant.

Demo

Open Stackblitz Open Code Sandbox Open on GitHub

Primary

Secondary

Drop to group by

	First Name	Last Name	Email	State
	Henry	Lynch	Camden.Macejkovic@yahoo.com	California
	Mckenna	Friesen	Veda_Feeney@yahoo.com	New York

Rows per page

1-2 of 2

This example is written for MRT V3.

If your app is still using MRT V1, either Upgrade to MRT V3 or use the V1 Docs instead. (useMaterialReactTable only exists in V2 and V3)

Source Code

1import { useMemo } from 'react';
2import {
3  MaterialReactTable,
4  useMaterialReactTable,
5  type MRT_ColumnDef,
6} from 'material-react-table';
7
8export type Employee = {
9  id: string;
10  firstName: string;
11  lastName: string;
12  email: string;
13  state: string;
14  managerId: string | null;
15};
16
17//flat data that TanStack Table's getSubRows() function will parse into a tree
18export const data: Employee[] = [
19  {
20    id: '9s41rp',
21    firstName: 'Kelvin',
22    lastName: 'Langosh',
23    email: 'Jerod14@hotmail.com',
24    state: 'Ohio',
25    managerId: '08m6rx',
26  },
27  {
28    id: '08m6rx',
29    firstName: 'Molly',
30    lastName: 'Purdy',
31    email: 'Hugh.Dach79@hotmail.com',
32    state: 'Rhode Island',
33    managerId: '5ymtrc',
34  },
35  {
36    id: '5ymtrc',
37    firstName: 'Henry',
38    lastName: 'Lynch',
39    email: 'Camden.Macejkovic@yahoo.com',
40    state: 'California',
41    managerId: null, //top of a tree
42  },
43  {
44    id: 'ek5b97',
45    firstName: 'Glenda',
46    lastName: 'Douglas',
47    email: 'Eric0@yahoo.com',
48    state: 'Montana',
49    managerId: '08m6rx',
50  },
51  {
52    id: 'xxtydd',
53    firstName: 'Leone',
54    lastName: 'Williamson',
55    email: 'Ericka_Mueller52@yahoo.com',
56    state: 'Colorado',
57    managerId: '08m6rx',
58  },
59  {
60    id: 'wzxj9m',
61    firstName: 'Mckenna',
62    lastName: 'Friesen',
63    email: 'Veda_Feeney@yahoo.com',
64    state: 'New York',
65    managerId: null, //top of a tree
66  },
67  {
68    id: '21dwtz',
69    firstName: 'Wyman',
70    lastName: 'Jast',
71    email: 'Melvin.Pacocha@yahoo.com',
72    state: 'Montana',
73    managerId: 'wzxj9m',
74  },
75  {
76    id: 'o8oe4k',
77    firstName: 'Janick',
78    lastName: 'Willms',
79    email: 'Delfina12@gmail.com',
80    state: 'Nebraska',
81    managerId: 'wzxj9m',
82  },
83];
84
85const Example = () => {
86  const columns = useMemo<MRT_ColumnDef<Employee>[]>(
87    //column definitions...
88    () => [
89      {
90        accessorKey: 'firstName',
91        header: 'First Name',
92      },
93      {
94        accessorKey: 'lastName',
95        header: 'Last Name',
96      },
97
98      {
99        accessorKey: 'email',
100        header: 'Email',
101      },
102      {
103        accessorKey: 'state',
104        header: 'State',
105      },
106    ],
107    [],
108    
109  );
110
111  //only root rows with no managerId
112  const rootData = useMemo(() => data.filter((r) => !r.managerId), [data]);
113
114  const table = useMaterialReactTable({
115    columns,
116    data: rootData,
117    enableExpanding: true,
118    //note: performance of this example should be improved with hash maps. This is currently 0(n^2)
119    getSubRows: (row) => data.filter((r) => r.managerId === row.id),
120  });
121
122  return <MaterialReactTable table={table} />;
123};
124
125export default Example;
126

Expanded Rows Pagination Behavior

By default, Material React Table will treat expanded sub-rows the same as any other row when it comes to pagination. This means that some expanded rows may be on the next page. You can change this behavior by setting the paginateExpandedRows table option to false.

const table = useMaterialReactTable({
  columns,
  data,
  enableExpanding: true,
  paginateExpandedRows: false, //expanded rows will be on the same page as their parent row
});

Expanded Leaf Row Filtering Behavior

If you are using the filtering features alongside sub-row features, then there are a few behaviors and customizations you should be aware of.

Filter From Leaf Rows

By default, filtering is done from parent rows down (so if a parent row is filtered out, all of its children will be filtered out as well). Setting the filterFromLeafRows table option to true will cause filtering to be done from leaf rows up (which means parent rows will be kept so long as one of their child, or grand-child, etc. rows pass the filtering).

const table = useMaterialReactTable({
  columns,
  data,
  enableExpanding: true,
  filterFromLeafRows: true, //search for child rows and preserve parent rows
});

Max Leaf Row Filter Depth

By default, filtering is done for all rows (max depth of 100), no matter if they are root level parent rows or the child leaf rows of a parent row. Setting the maxLeafRowFilterDepth table option to 0 will cause filtering to only be applied to the root level parent rows, with all sub-rows remaining unfiltered. Similarly, setting this option to 1 will cause filtering to only be applied to child leaf rows 1 level deep, and so on.

This is useful for situations where you want a row's entire child hierarchy to be visible, regardless of the applied filter.

const table = useMaterialReactTable({
  columns,
  data,
  enableExpanding: true,
  maxLeafRowFilterDepth: 0, //When filtering root rows, keep all child rows of the passing parent rows
});

Expand All Rows By Default

You can manage the initial state of the expanded rows with the expanded state option in either the initialState or state props.

For example, you may want all rows to be expanded by default. To do this, you can simply set the expanded state option to true.

const table = useMaterialReactTable({
  columns,
  data,
  enableExpanding: true,
  initialState: { expanded: true }, //all rows expanded by default
});

Demo

Open Stackblitz Open Code Sandbox Open on GitHub

Primary

Secondary

Drop to group by

First Name	Last Name	Address	City	State
Dylan	Murray	261 Erdman Ford	East Daphne	Kentucky
Ervin	Reinger	566 Brakus Inlet	South Linda	West Virginia
Jordane	Homenick	1234 Brakus Inlet	South Linda	West Virginia
Jordan	Clarkson	4882 Palm Rd	San Francisco	California
Brittany	McCullough	722 Emie Stream	Lincoln	Nebraska
Raquel	Kohler	769 Dominic Grove	Columbus	Ohio
Branson	Frami	32188 Larkin Turnpike	Charleston	South Carolina

Rows per page

1-2 of 2

This example is written for MRT V3.

If your app is still using MRT V1, either Upgrade to MRT V3 or use the V1 Docs instead. (useMaterialReactTable only exists in V2 and V3)

Source Code

1import { useMemo } from 'react';
2import {
3  MaterialReactTable,
4  useMaterialReactTable,
5  type MRT_ColumnDef,
6} from 'material-react-table';
7
8export type Person = {
9  firstName: string;
10  lastName: string;
11  address: string;
12  city: string;
13  state: string;
14  subRows?: Person[]; //Each person can have sub rows of more people
15};
16
17export const data: Person[] = [
18  {
19    firstName: 'Dylan',
20    lastName: 'Murray',
21    address: '261 Erdman Ford',
22    city: 'East Daphne',
23    state: 'Kentucky',
24    subRows: [
25      {
26        firstName: 'Ervin',
27        lastName: 'Reinger',
28        address: '566 Brakus Inlet',
29        city: 'South Linda',
30        state: 'West Virginia',
31        subRows: [
32          {
33            firstName: 'Jordane',
34            lastName: 'Homenick',
35            address: '1234 Brakus Inlet',
36            city: 'South Linda',
37            state: 'West Virginia',
38          },
39          {
40            firstName: 'Jordan',
41            lastName: 'Clarkson',
42            address: '4882 Palm Rd',
43            city: 'San Francisco',
44            state: 'California',
45          },
46        ],
47      },
48      {
49        firstName: 'Brittany',
50        lastName: 'McCullough',
51        address: '722 Emie Stream',
52        city: 'Lincoln',
53        state: 'Nebraska',
54      },
55    ],
56  },
57  {
58    firstName: 'Raquel',
59    lastName: 'Kohler',
60    address: '769 Dominic Grove',
61    city: 'Columbus',
62    state: 'Ohio',
63    subRows: [
64      {
65        firstName: 'Branson',
66        lastName: 'Frami',
67        address: '32188 Larkin Turnpike',
68        city: 'Charleston',
69        state: 'South Carolina',
70      },
71    ],
72  },
73];
74
75const Example = () => {
76  const columns = useMemo<MRT_ColumnDef<Person>[]>(
77    //column definitions...
78    () => [
79      {
80        accessorKey: 'firstName',
81        header: 'First Name',
82      },
83      {
84        accessorKey: 'lastName',
85        header: 'Last Name',
86      },
87
88      {
89        accessorKey: 'address',
90        header: 'Address',
91      },
92      {
93        accessorKey: 'city',
94        header: 'City',
95      },
96
97      {
98        accessorKey: 'state',
99        enableColumnOrdering: false,
100        header: 'State',
101      },
102    ],
103    [],
104    
105  );
106
107  const table = useMaterialReactTable({
108    columns,
109    data,
110    enableExpandAll: false, //hide expand all double arrow in column header
111    enableExpanding: true,
112    filterFromLeafRows: true, //apply filtering to all rows instead of just parent rows
113    getSubRows: (row) => row.subRows, //default
114    initialState: { expanded: true }, //expand all rows by default
115    paginateExpandedRows: false, //When rows are expanded, do not count sub-rows as number of rows on the page towards pagination
116  });
117
118  return <MaterialReactTable table={table} />;
119};
120
121export default Example;
122

Expand Root Rows Only By Default

Here is a slightly more complex initial expanded state example where all the root rows are expanded by default, but none of the sub rows themselves are expanded by default. We just need to find all of the root row ids and set their key in the expanded initialState option to true.

Demo

Open Stackblitz Open Code Sandbox Open on GitHub

Primary

Secondary

Drop to group by

First Name	Last Name	Address	City	State
Dylan	Murray	261 Erdman Ford	East Daphne	Kentucky
Ervin	Reinger	566 Brakus Inlet	South Linda	West Virginia
Brittany	McCullough	722 Emie Stream	Lincoln	Nebraska
Raquel	Kohler	769 Dominic Grove	Columbus	Ohio
Branson	Frami	32188 Larkin Turnpike	Charleston	South Carolina

Rows per page

1-5 of 5

This example is written for MRT V3.

If your app is still using MRT V1, either Upgrade to MRT V3 or use the V1 Docs instead. (useMaterialReactTable only exists in V2 and V3)

Source Code

1import { useMemo } from 'react';
2import {
3  MaterialReactTable,
4  type MRT_ExpandedState,
5  type MRT_ColumnDef,
6  useMaterialReactTable,
7} from 'material-react-table';
8import { Button } from '@mui/material';
9
10export type Person = {
11  id: string;
12  firstName: string;
13  lastName: string;
14  address: string;
15  city: string;
16  state: string;
17  subRows?: Person[]; //Each person can have sub rows of more people
18};
19
20//data definitions...
21export const data: Person[] = [
22  {
23    id: '1',
24    firstName: 'Dylan',
25    lastName: 'Murray',
26    address: '261 Erdman Ford',
27    city: 'East Daphne',
28    state: 'Kentucky',
29    subRows: [
30      {
31        id: '2',
32        firstName: 'Ervin',
33        lastName: 'Reinger',
34        address: '566 Brakus Inlet',
35        city: 'South Linda',
36        state: 'West Virginia',
37        subRows: [
38          {
39            id: '3',
40            firstName: 'Jordane',
41            lastName: 'Homenick',
42            address: '1234 Brakus Inlet',
43            city: 'South Linda',
44            state: 'West Virginia',
45          },
46          {
47            id: '4',
48            firstName: 'Jordan',
49            lastName: 'Clarkson',
50            address: '4882 Palm Rd',
51            city: 'San Francisco',
52            state: 'California',
53          },
54        ],
55      },
56      {
57        id: '5',
58        firstName: 'Brittany',
59        lastName: 'McCullough',
60        address: '722 Emie Stream',
61        city: 'Lincoln',
62        state: 'Nebraska',
63      },
64    ],
65  },
66  {
67    id: '6',
68    firstName: 'Raquel',
69    lastName: 'Kohler',
70    address: '769 Dominic Grove',
71    city: 'Columbus',
72    state: 'Ohio',
73    subRows: [
74      {
75        id: '7',
76        firstName: 'Branson',
77        lastName: 'Frami',
78        address: '32188 Larkin Turnpike',
79        city: 'Charleston',
80        state: 'South Carolina',
81        subRows: [
82          {
83            id: '8',
84            firstName: 'Henry',
85            lastName: 'Ford',
86            address: '1234 Brakus Inlet',
87            city: 'Nashville',
88            state: 'Tennessee',
89          },
90        ],
91      },
92    ],
93  },
94];
95
96
97const Example = () => {
98  const columns = useMemo<MRT_ColumnDef<Person>[]>(
99    //column definitions...
100    () => [
101      {
102        accessorKey: 'firstName',
103        header: 'First Name',
104      },
105      {
106        accessorKey: 'lastName',
107        header: 'Last Name',
108      },
109
110      {
111        accessorKey: 'address',
112        header: 'Address',
113      },
114      {
115        accessorKey: 'city',
116        header: 'City',
117      },
118
119      {
120        accessorKey: 'state',
121        enableColumnOrdering: false,
122        header: 'State',
123      },
124    ],
125    [],
126    
127  );
128
129  const initialExpandedRootRows = useMemo<MRT_ExpandedState>(
130    () =>
131      data
132        .map((originalRow) => originalRow.id) //get all the root row ids, use recursion for additional levels
133        .reduce((a, v) => ({ ...a, [v]: true }), {}), //convert to an object with all the ids as keys and `true` as values
134    [],
135  );
136
137  const table = useMaterialReactTable({
138    columns,
139    data,
140    enableExpanding: true,
141    getRowId: (originalRow) => originalRow.id,
142    initialState: { expanded: initialExpandedRootRows }, //only expand the root rows by default
143    renderTopToolbarCustomActions: ({ table }) => (
144      <Button onClick={() => table.resetExpanded()}>Reset Expanded</Button>
145    ),
146  });
147
148  return <MaterialReactTable table={table} />;
149};
150
151export default Example;
152

Customize Expand Column

You can customize the expand column by using the displayColumnDefOptions table option.

const table = useMaterialReactTable({
  columns,
  data,
  enableGrouping: true,
  displayColumnDefOptions: {
    'mrt-row-expand': {
      enableResizing: true, //allow resizing
      size: 120, //make the expand column wider
    },
  },
});

Lazy Load Sub Rows

If you have a ton of nested data that you want to display, but you don't want to fetch it all up front, you can set up Material React Table to only fetch the sub-rows data when the user expands the row.

There are quite a few ways in which you could implement fetching sub-rows lazily. This example is just one way to do it.

The main concept to understand from this example is that you can manage the expanded state option in your own scope, and fetch the data for your table based on that state.

How your data is structured from the server is up to you. It is usually easiest to have the server do the hard work and return the data in a nested tree structure, but you can also return the data in a flat structure and use the getSubRows table option to parse the data into a tree structure.

Demo

Open Stackblitz Open Code Sandbox Open on GitHub

Primary

Secondary

Drop to group by

	First Name	Last Name	Email	State

Rows per page

0-0 of 0

This example is written for MRT V3.

If your app is still using MRT V1, either Upgrade to MRT V3 or use the V1 Docs instead. (useMaterialReactTable only exists in V2 and V3)

Source Code

1import { useMemo, useState } from 'react';
2import {
3  MaterialReactTable,
4  useMaterialReactTable,
5  type MRT_ColumnDef,
6  type MRT_PaginationState,
7  type MRT_SortingState,
8  type MRT_ExpandedState,
9} from 'material-react-table';
10import {
11  QueryClient,
12  QueryClientProvider,
13  keepPreviousData,
14  useQuery,
15} from '@tanstack/react-query'; //note: this is TanStack React Query V5
16
17//Your API response shape will probably be different. Knowing a total row count is important though.
18type UserApiResponse = {
19  data: Array<User>;
20  meta: {
21    totalRowCount: number;
22  };
23};
24
25type User = {
26  id: string;
27  firstName: string;
28  lastName: string;
29  email: string;
30  state: string;
31  managerId: string | null; //row's parent row id
32  subordinateIds: string[]; //or some type of boolean that indicates that there are sub-rows
33};
34
35const columns: MRT_ColumnDef<User>[] = [
36  //column definitions...
37  {
38    accessorKey: 'firstName',
39    header: 'First Name',
40  },
41  {
42    accessorKey: 'lastName',
43    header: 'Last Name',
44  },
45  {
46    accessorKey: 'email',
47    header: 'Email',
48  },
49  {
50    accessorKey: 'state',
51    header: 'State',
52  },
53  
54];
55
56const Example = () => {
57  const [sorting, setSorting] = useState<MRT_SortingState>([]);
58  const [pagination, setPagination] = useState<MRT_PaginationState>({
59    pageIndex: 0,
60    pageSize: 10,
61  });
62  const [expanded, setExpanded] = useState<MRT_ExpandedState>({}); //Record<string, boolean> | true
63
64  //which rows have sub-rows expanded and need their direct sub-rows to be included in the API call
65  const expandedRowIds: string[] | 'all' = useMemo(
66    () =>
67      expanded === true
68        ? 'all'
69        : Object.entries(expanded)
70            .filter(([_managerId, isExpanded]) => isExpanded)
71            .map(([managerId]) => managerId),
72    [expanded],
73  );
74
75  const {
76    data: { data = [], meta } = {},
77    isError,
78    isRefetching,
79    isLoading,
80  } = useFetchUsers({
81    pagination,
82    sorting,
83    expandedRowIds,
84  });
85
86  //get data for root rows only (top of the tree data)
87  const rootData = useMemo(() => data.filter((r) => !r.managerId), [data]);
88
89  const table = useMaterialReactTable({
90    columns,
91    data: rootData,
92    enableExpanding: true, //enable expanding column
93    enableFilters: false,
94    //tell MRT which rows have additional sub-rows that can be fetched
95    getRowCanExpand: (row) => !!row.original.subordinateIds.length, //just some type of boolean
96    //identify rows by the user's id
97    getRowId: (row) => row.id,
98    //if data is delivered in a flat array, MRT can convert it to a tree structure
99    //though it's usually better if the API can construct the nested structure before this point
100    getSubRows: (row) => data.filter((r) => r.managerId === row.id), //parse flat array into tree structure
101    // paginateExpandedRows: false, //the back-end in this example is acting as if this option is false
102    manualPagination: true, //turn off built-in client-side pagination
103    manualSorting: true, //turn off built-in client-side sorting
104    muiToolbarAlertBannerProps: isError
105      ? {
106          color: 'error',
107          children: 'Error loading data',
108        }
109      : undefined,
110    onExpandedChange: setExpanded,
111    onPaginationChange: setPagination,
112    onSortingChange: setSorting,
113    rowCount: meta?.totalRowCount ?? 0,
114    state: {
115      expanded,
116      isLoading,
117      pagination,
118      showAlertBanner: isError,
119      showProgressBars: isRefetching,
120      sorting,
121    },
122  });
123
124  return <MaterialReactTable table={table} />;
125};
126
127const queryClient = new QueryClient();
128
129const ExampleWithReactQueryProvider = () => (
130  //App.tsx or AppProviders file. Don't just wrap this component with QueryClientProvider! Wrap your whole App!
131  <QueryClientProvider client={queryClient}>
132    <Example />
133  </QueryClientProvider>
134);
135
136export default ExampleWithReactQueryProvider;
137
138//fetch user hook
139const useFetchUsers = ({
140  pagination,
141  sorting,
142  expandedRowIds,
143}: {
144  pagination: MRT_PaginationState;
145  sorting: MRT_SortingState;
146  expandedRowIds: string[] | 'all';
147}) => {
148  return useQuery<UserApiResponse>({
149    queryKey: [
150      'users', //give a unique key for this query
151      pagination.pageIndex, //refetch when pagination.pageIndex changes
152      pagination.pageSize, //refetch when pagination.pageSize changes
153      sorting, //refetch when sorting changes
154      expandedRowIds,
155    ],
156    queryFn: async () => {
157      const fetchURL = new URL('/api/treedata', location.origin);
158
159      //read our state and pass it to the API as query params
160      fetchURL.searchParams.set(
161        'start',
162        `${pagination.pageIndex * pagination.pageSize}`,
163      );
164      fetchURL.searchParams.set('size', `${pagination.pageSize}`);
165      fetchURL.searchParams.set('sorting', JSON.stringify(sorting ?? []));
166      fetchURL.searchParams.set(
167        'expandedRowIds',
168        expandedRowIds === 'all' ? 'all' : JSON.stringify(expandedRowIds ?? []),
169      );
170
171      //use whatever fetch library you want, fetch, axios, etc
172      const response = await fetch(fetchURL.href);
173      const json = (await response.json()) as UserApiResponse;
174      return json;
175    },
176    placeholderData: keepPreviousData, //don't go to 0 rows when refetching or paginating to next page
177  });
178};
179