Infinite scroll

In this recipe, we'll add infinite scroll to our application. Superglue doesn't have an infinite scroll component, but it has tools that make it easy to work with React's ecosystem.

Lets begin by adding react-infinite-scroll-hook

yarn add react-infinite-scroll-hook

And continue off from our pagination recipe.

!!! tip We'll use the beforeSave callback to modify the payload before superglue saves it to the store. This callback is an option for both visit and remote functions. See the beforeSave reference for more details.

// app/views/posts/index.js

import React from 'react'
- import {useContent} from '@thoughtbot/superglue'
+ import {useContent, NavigationContext} from '@thoughtbot/superglue'
import PostList from './PostList'
import Header from './Header'
+ import useInfiniteScroll from 'react-infinite-scroll-hook';

export default PostIndex = () => {
  const {
    posts,
    header,
    pathToNextPage,
    pathToPrevPage
  } = useContent()

+ const { remote, pageKey } = useContext(NavigationContext)
+ const { loading, setLoading } = useState(false)
+ const hasNextPage = !!pathToNextPage
+
+ const beforeSave = (prevPage, receivedPage) => {
+   const prevPosts = prevPage.data.posts
+   const receivedPosts = receivedPage.data.posts
+   receivedPage.data.posts = prevPosts + receivedPosts
+
+   return receivedPage
+ }
+
+ const loadMore = () => {
+   setLoading(true)
+   remote(pathToNextPage, {pageKey, beforeSave})
+     .then(() => setLoading(false))
+ }
+
+ const [sentryRef] = useInfiniteScroll({
+   loading,
+   hasNextPage,
+   onLoadMore: loadMore,
+ });

  return (
    <>
      <Header {...header}/>
      <div>
        {
          posts.list.map(({id, body}) => (
            <p key={id}>{body}</p>
          ))
        }
+       {(loading || hasNextPage) && (
+         <p ref={sentryRef}>
+           loading
+         </p>
+       )}
      </div>
-     {pathToPrevPage && <a href={pathToPrevPage} data-sg-visit>Prev Page</a>}
-     {pathToNextPage && <a href={pathToNextPage} data-sg-visit>Next Page</a>}
    </>
  )
}