dcaaef1011
Format: YYYY-MM-DD-description.md - 2026-01-19-infrastructure-deployment.md - 2026-01-19-backend-api-implementation.md (in progress) Co-Authored-By: Claude Sonnet 4.5 (1M context) <noreply@anthropic.com>
57 lines
1.1 KiB
Markdown
57 lines
1.1 KiB
Markdown
---
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title: Use SWR for Automatic Deduplication
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impact: MEDIUM-HIGH
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impactDescription: automatic deduplication
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tags: client, swr, deduplication, data-fetching
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---
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## Use SWR for Automatic Deduplication
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SWR enables request deduplication, caching, and revalidation across component instances.
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**Incorrect (no deduplication, each instance fetches):**
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```tsx
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function UserList() {
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const [users, setUsers] = useState([])
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useEffect(() => {
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fetch('/api/users')
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.then(r => r.json())
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.then(setUsers)
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}, [])
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}
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```
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**Correct (multiple instances share one request):**
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```tsx
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import useSWR from 'swr'
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function UserList() {
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const { data: users } = useSWR('/api/users', fetcher)
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}
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```
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**For immutable data:**
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```tsx
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import { useImmutableSWR } from '@/lib/swr'
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function StaticContent() {
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const { data } = useImmutableSWR('/api/config', fetcher)
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}
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```
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**For mutations:**
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```tsx
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import { useSWRMutation } from 'swr/mutation'
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function UpdateButton() {
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const { trigger } = useSWRMutation('/api/user', updateUser)
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return <button onClick={() => trigger()}>Update</button>
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}
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```
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Reference: [https://swr.vercel.app](https://swr.vercel.app)
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