How to use the useSWRInfinite hook for paginating data with a custom response transformation in Next.js



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To use the useSWRInfinite hook for paginating data with a custom response transformation in Next.js, you first need to install the swr library if you haven't already:

bash
npm install swr
# or
yarn add swr

Then, you can create a custom hook to handle the pagination logic and data fetching. Below is an example of how you can implement this:

jsx
// customHooks/useCustomSWRInfinite.js
import useSWRInfinite from 'swr';
import fetcher from '../utils/fetcher'; // fetcher is a custom function to fetch data, you need to implement this

const PAGE_SIZE = 10; // Define your page size here

const useCustomSWRInfinite = (endpoint) => {
  const getKey = (pageIndex, previousPageData) => {
    // If there's no previous page data, this is the first page
    if (pageIndex === 0) {
      return `${endpoint}?_page=1&_limit=${PAGE_SIZE}`;
    }

    // If there are more items, fetch the next page
    if (previousPageData.length === PAGE_SIZE) {
      return `${endpoint}?_page=${pageIndex + 1}&_limit=${PAGE_SIZE}`;
    }

    // All items have been loaded
    return null;
  };

  const { data, error, size, setSize } = useSWRInfinite(getKey, fetcher);

  // Transform data if needed
  const transformedData = data ? data.flatMap(page => page.results) : [];

  return {
    data: transformedData,
    isLoading: !data && !error,
    isError: error,
    size,
    setSize
  };
};

export default useCustomSWRInfinite;

In this hook:

  • getKey function generates the URL based on the page index.
  • useSWRInfinite is used to fetch data based on the generated keys.
  • fetcher is a custom function to fetch data, you need to implement this according to your API setup.
  • transformedData is where you can apply custom transformations to your data.
  • isLoading, isError, size, and setSize are returned from useSWRInfinite.

Now, you can use this custom hook in your Next.js components:

jsx
// YourComponent.js
import useCustomSWRInfinite from '../customHooks/useCustomSWRInfinite';

const YourComponent = () => {
  const { data, isLoading, isError, size, setSize } = useCustomSWRInfinite('/api/data');

  if (isLoading) return <div>Loading...</div>;
  if (isError) return <div>Error fetching data</div>;

  return (
    <div>
      {data.map((item, index) => (
        <div key={index}>{/* Render your item */}</div>
      ))}
      <button onClick={() => setSize(size + 1)}>Load More</button>
    </div>
  );
};

export default YourComponent;

Ensure you replace '/api/data' with your actual API endpoint. This code will fetch and display paginated data, with a "Load More" button to load more items.

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