Kwa nini kutumia maktaba ya hali ya server kama React Query?

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**Maktaba za hali ya server** (React Query/TanStack Query, SWR, RTK Query) ni maalum katika usimamizi wa **data iliyoletwa kutoka kwenye server** — kwa kuzitumia kama cache ili kuendelea kwa sambamba na chanzo cha mbali. Zinasimamia caching, loading/error states, re-fetching, na deduplication kiotomatiki, na kuongeza sehemu kubwa ya msimbo wa manual. ## Tatizo: data ya server si kama hali ya UI Data ya server *inaimilikiwa na server* na tu imetengenezwa kama cache kwenye mteja, kwa hivyo inaweza kuwa **zamani**. Kusimamia kwa manual kunamaanisha kutengeneza upya caching, kurekodi loading/errors, re-fetching, majaribio, na deduplication kwa kila endpoint — wenye makosa na kurudia. ## Nini React Query inakupatia katika hook moja ```jsx import { useQuery } from "@tanstack/react-query"; function Users() { const { data, isLoading, error, refetch } = useQuery({ queryKey: ["users"], // cache key queryFn: () => fetch("/api/users").then(r => r.json()), staleTime: 60_000, // consider fresh for 1 min }); if (isLoading) return ; if (error) return ; return ; } ``` Hook hiyo moja inatoa: ```text ✓ Caching — data cached by queryKey, shared across components ✓ Loading/error — isLoading/error states managed for you ✓ Deduplication — same query in 5 components = ONE network request ✓ Background refetch— refetch on window focus/reconnect to stay fresh ✓ Stale-while-revalidate — show cached data instantly, refetch in background ✓ Retries — auto-retry failed requests ✓ Pagination/infinite scroll, prefetching, cache invalidation ``` ## Mutations + cache invalidation ```jsx const mutation = useMutation({ mutationFn: (user) => api.createUser(user), onSuccess: () => queryClient.invalidateQueries({ queryKey: ["users"] }), // refetch the list }); ``` Baada ya mutation, unabatilisha swali husika na cache inapakua tena — kuweka UI inaongana na server. ## Inapunguza mahitaji yako ya "global state" ```text Much of what people put in Redux is actually SERVER state. Moving it to React Query often shrinks global state to just true UI state (theme, modals, filters) — simplifying the whole app. ``` ## Kwa nini jambo hili lina umuhimu Maktaba za hali ya server zinarudia tatizo ambalo zana za hali ya jumla (Redux, useState) zinashindwa: kuweka cache ya mteja inaongana na data ya mbali. Zinabadilisha mamia ya mistari ya msimbo wa manual wa fetching/caching/loading na hooks ya kaandishi, na hutoa tabia ya kipenzi (dedup, background refetch, stale-while-revalidate) ambayo ni ngumu kujenga kwa usahihi kwa mkono. Kugundua kuwa hali ya server inastahili zana yake yenyewe ya kukamatia — na kuanguka kwenye moja kawaida kurahisisha sana hali ya jumla — ni mmoja wa maarifa yangu ya ulimwengu wa frontend ambayo ina matokeo makubwa.