React table with sorting and pagination doesn't update

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06-10-2024

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React Table Sorting and Pagination: Why Your Data Isn't Updating

Frustrated with your React table's sorting and pagination features not working as expected? It's a common issue developers encounter when building dynamic tables. This article delves into the root causes of this problem, explores solutions, and equips you with the knowledge to create seamless and efficient sorting and pagination in your React table.

The Scenario: Stuck in a Data Loop

Imagine you've meticulously implemented sorting and pagination in your React table using a popular library like react-table. You've carefully wired up the sorting and pagination logic, but the table data remains stagnant.

Here's a simplified example using react-table:

import React, { useState } from 'react';
import { useTable } from 'react-table';

const MyTable = ({ data }) => {
  const [currentPage, setCurrentPage] = useState(1);
  const [sortedData, setSortedData] = useState(data);

  const handleSort = (column) => {
    const sorted = [...sortedData].sort((a, b) => {
      if (a[column.id] < b[column.id]) return -1;
      if (a[column.id] > b[column.id]) return 1;
      return 0;
    });
    setSortedData(sorted);
  };

  const columns = [
    { Header: 'Name', accessor: 'name' },
    { Header: 'Age', accessor: 'age' },
    { Header: 'City', accessor: 'city' },
  ];

  const {
    getTableProps,
    getTableBodyProps,
    headerGroups,
    rows,
    prepareRow,
  } = useTable({
    columns,
    data: sortedData.slice((currentPage - 1) * 10, currentPage * 10), // Paginate data
  });

  return (
    <table {...getTableProps()}>
      <thead>
        {headerGroups.map((headerGroup) => (
          <tr {...headerGroup.getHeaderGroupProps()}>
            {headerGroup.headers.map((column) => (
              <th
                {...column.getHeaderProps()}
                onClick={() => handleSort(column)}
              >
                {column.render('Header')}
              </th>
            ))}
          </tr>
        ))}
      </thead>
      <tbody {...getTableBodyProps()}>
        {rows.map((row, i) => {
          prepareRow(row);
          return (
            <tr {...row.getRowProps()}>
              {row.cells.map((cell) => {
                return (
                  <td {...cell.getCellProps()}>{cell.render('Cell')}</td>
                );
              })}
            </tr>
          );
        })}
      </tbody>
    </table>
  );
};

export default MyTable;

In this scenario, the table doesn't update when you sort or change pages. This usually stems from a misunderstanding of how react-table and state management work together.

The Culprit: Ignoring State Changes

The problem lies in the way state updates are handled within react-table. Here's the key point: react-table doesn't automatically re-render the entire table when the data or pagination state changes. It only re-renders individual cells or rows that are affected by the change.

In the example above, the sortedData state is updated when a column is sorted, but this update doesn't automatically trigger a re-render of the table. Similarly, the pagination logic uses a slice of the sortedData array, but this slice is not dynamically linked to the original data.

The Solution: Leverage useMemo

To achieve the desired behavior, we need to use useMemo to ensure that the data being displayed in the table is consistently updated when either the sorting or pagination state changes.

Here's how we can modify our example:

import React, { useState, useMemo } from 'react';
import { useTable } from 'react-table';

const MyTable = ({ data }) => {
  const [currentPage, setCurrentPage] = useState(1);
  const [sortedData, setSortedData] = useState(data);

  const handleSort = (column) => {
    const sorted = [...sortedData].sort((a, b) => {
      if (a[column.id] < b[column.id]) return -1;
      if (a[column.id] > b[column.id]) return 1;
      return 0;
    });
    setSortedData(sorted);
  };

  const columns = [
    { Header: 'Name', accessor: 'name' },
    { Header: 'Age', accessor: 'age' },
    { Header: 'City', accessor: 'city' },
  ];

  const paginatedData = useMemo(() => {
    return sortedData.slice((currentPage - 1) * 10, currentPage * 10);
  }, [sortedData, currentPage]); // Depend on both states

  const {
    getTableProps,
    getTableBodyProps,
    headerGroups,
    rows,
    prepareRow,
  } = useTable({
    columns,
    data: paginatedData, // Pass the memoized data
  });

  return (
    // ... table structure
  );
};

export default MyTable;

By wrapping the pagination logic in useMemo, we create a derived data array paginatedData that depends on both sortedData and currentPage. Whenever either of these states changes, paginatedData will be recalculated, ensuring that the table receives the correct data for rendering.

Key Takeaways

• Understand react-table's Re-rendering Behavior: react-table doesn't automatically re-render the entire table for state changes.
• Use useMemo for Derived Data: useMemo allows you to create a memoized version of your data that is automatically updated whenever the underlying state changes.
• Depend on All Relevant States: When using useMemo, ensure the memoized function depends on all the states that can influence the derived data.

By applying these best practices, you'll eliminate the data stagnation and achieve smooth sorting and pagination in your React table.