File size: 3,937 Bytes
1e92f2d |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 |
import React from 'react'
import ReactDOM from 'react-dom/client'
import {
QueryClient,
QueryClientProvider,
useQuery,
useQueryClient,
} from '@tanstack/react-query'
import { ReactQueryDevtools } from '@tanstack/react-query-devtools'
import type { QueryKey } from '@tanstack/react-query'
type Post = {
id: number
title: string
body: string
}
// Define a default query function that will receive the query key
const defaultQueryFn = async ({ queryKey }: { queryKey: QueryKey }) => {
const response = await fetch(
`https://jsonplaceholder.typicode.com${queryKey[0]}`,
)
return await response.json()
}
// provide the default query function to your app via the query client
const queryClient = new QueryClient({
defaultOptions: {
queries: {
queryFn: defaultQueryFn,
},
},
})
function App() {
const [postId, setPostId] = React.useState(-1)
return (
<QueryClientProvider client={queryClient}>
<p>
As you visit the posts below, you will notice them in a loading state
the first time you load them. However, after you return to this list and
click on any posts you have already visited again, you will see them
load instantly and background refresh right before your eyes!{' '}
<strong>
(You may need to throttle your network speed to simulate longer
loading sequences)
</strong>
</p>
{postId > -1 ? (
<Post postId={postId} setPostId={setPostId} />
) : (
<Posts setPostId={setPostId} />
)}
<ReactQueryDevtools initialIsOpen />
</QueryClientProvider>
)
}
function Posts({
setPostId,
}: {
setPostId: React.Dispatch<React.SetStateAction<number>>
}) {
const queryClient = useQueryClient()
// All you have to do now is pass a key!
const { status, data, error, isFetching } = useQuery<Array<Post>>({
queryKey: ['/posts'],
})
return (
<div>
<h1>Posts</h1>
<div>
{status === 'pending' ? (
'Loading...'
) : status === 'error' ? (
<span>Error: {error.message}</span>
) : (
<>
<div>
{data.map((post) => (
<p key={post.id}>
<a
onClick={() => setPostId(post.id)}
href="#"
style={
// We can use the queryCache here to show bold links for
// ones that are cached
queryClient.getQueryData([`/posts/${post.id}`])
? {
fontWeight: 'bold',
color: 'green',
}
: {}
}
>
{post.title}
</a>
</p>
))}
</div>
<div>{isFetching ? 'Background Updating...' : ' '}</div>
</>
)}
</div>
</div>
)
}
function Post({
postId,
setPostId,
}: {
postId: number
setPostId: React.Dispatch<React.SetStateAction<number>>
}) {
// You can even leave out the queryFn and just go straight into options
const { status, data, error, isFetching } = useQuery<Post>({
queryKey: [`/posts/${postId}`],
enabled: !!postId,
})
return (
<div>
<div>
<a onClick={() => setPostId(-1)} href="#">
Back
</a>
</div>
{!postId || status === 'pending' ? (
'Loading...'
) : status === 'error' ? (
<span>Error: {error.message}</span>
) : (
<>
<h1>{data.title}</h1>
<div>
<p>{data.body}</p>
</div>
<div>{isFetching ? 'Background Updating...' : ' '}</div>
</>
)}
</div>
)
}
const rootElement = document.getElementById('root') as HTMLElement
ReactDOM.createRoot(rootElement).render(<App />)
|