How to use debounce with useQuery in React Query?

Using useQuery to initiate a request with debouncing is not directly supported in React Query because useQuery is typically designed for immediate data fetching. However, you can achieve this by using debounce functions (such as the debounce function from the lodash library). The key is to apply the debouncing logic to the event that triggers the query, rather than directly to useQuery.

Here is an example of how to implement a debounced request:

First, you need to install lodash as a project dependency since we will use its debounce function.

bash
npm install lodash

Then, you can create a debounced function within the component to trigger the React Query query.

jsx
import React, { useState } from 'react';
import { useQuery } from 'react-query';
import { debounce } from 'lodash';

const fetchData = async (searchText) => {
  const response = await fetch('/api/data?search=' + encodeURIComponent(searchText));
  if (!response.ok) {
    throw new Error('Network response was not ok');
  }
  return response.json();
};

function SearchComponent() {
  // Set up a state to store the search text
  const [searchText, setSearchText] = useState('');

  // Use react-query's `useQuery`, but do not trigger the request directly
  // We pass a unique query key and use the current `searchText` state in the query function
  // This way, the request is executed only when `searchText` changes
  const { data, error, isLoading } = useQuery(
    ['search', searchText], 
    () => fetchData(searchText),
    {
      // Do not execute the query if `searchText` is empty
      enabled: searchText.trim() !== ''
    }
  );

  // Create a debounced function to update `searchText` state
  // This debounced function will execute after a delay once the user stops typing
  const debouncedSetSearchText = debounce(setSearchText, 300);

  // This function handles input changes
  // It is debounced, so it won't update the state or trigger the request for every keystroke
  const handleSearchChange = (event) => {
    const value = event.target.value;
    debouncedSetSearchText(value);
  };

  return (
    <div>
      <input
        type="text"
        placeholder="Search..."
        onChange={handleSearchChange}
      />
      {isLoading ? (
        <div>Loading...</div>
      ) : error ? (
        <div>Error: {error.message}</div>
      ) : (
        <div>
          {/* Render data */}
        </div>
      )}
    </div>
  );
}

In the above code, the handleSearchChange function is called when the user types and updates the searchText state through the debounced function debouncedSetSearchText. Since we configure the enabled option in useQuery to be true only when searchText is not empty, the data request is triggered only after the debounced function executes and searchText has a value.

This way, even if the user types quickly in the input field, multiple requests are not sent. Instead, the request is initiated based on the latest search term only after the user stops typing for a specified duration (in this example, 300ms), achieving the debouncing effect.