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https://github.com/mauriceboe/TREK.git
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jubnl
bcd2c8c959
Repos gated reads on raw navigator.onLine and the online branch had no try/catch, so a captive portal or connected-but-no-internet (navigator.onLine lying "true") threw a network error instead of serving the good cached copy — blanking the trip even though Dexie held it. - new onlineThenCache(onlineFn, cacheFn) helper: reads the cache when offline, and on a network-level failure (Axios error with no HTTP response). A genuine HTTP error (4xx/5xx — the server responded) is rethrown so callers still set error state / navigate, not masked by a stale cache. - gates only on navigator.onLine, NOT the connectivity probe: the probe is a coarse global flag and one failed health check would otherwise divert every read to the (possibly empty) cache even when the request would succeed. - every repo list/get read path routed through it (reads only — writes still go through the mutation queue so failures surface) - tests: captive-portal fallback, HTTP-error rethrow, non-Axios rethrow
49 lines
2.1 KiB
TypeScript
49 lines
2.1 KiB
TypeScript
/**
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* True when an error means the request never reached the server — a network-level
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* failure (offline, captive portal, proxy auth wall, dropped connection, CORS).
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* Axios sets `response` only when the server actually replied; its absence (on an
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* Axios error) means we never got one. A real HTTP error (4xx/5xx) HAS a response
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* and must NOT be treated as a network failure — the server spoke, so the caller
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* needs to see it. Non-Axios errors are surfaced too.
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*/
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function isNetworkError(err: unknown): boolean {
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const e = err as { isAxiosError?: boolean; response?: unknown } | null
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return !!e && e.isAxiosError === true && e.response == null
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}
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/**
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* Read-through cache pattern shared by every repo's read methods.
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*
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* Reads degrade to the local Dexie cache in two situations:
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* 1. The browser reports it is offline (`navigator.onLine` false) — skip the
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* doomed request entirely.
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* 2. The browser *thinks* it is online but the request fails at the network
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* level — a lying `navigator.onLine` on a captive portal, a dropped
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* connection (H2). Rather than surfacing that (which blanks the trip even
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* though a good cached copy exists), we fall back to the cache.
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*
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* We intentionally gate only on `navigator.onLine`, NOT the connectivity probe:
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* the probe is a coarse global flag, and a single failed health check would
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* otherwise force every read to the (possibly empty) cache even when the request
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* itself would succeed. The network-error catch below covers the captive-portal
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* case the probe was meant to.
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*
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* A genuine HTTP error (404/403/500 — the server responded) is NOT swallowed: it
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* is rethrown so callers can set error state, navigate away, etc.
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*
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* Writes must NOT use this — they go through the mutation queue so failures are
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* surfaced and retried, not silently swallowed.
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*/
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export async function onlineThenCache<T>(
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onlineFn: () => Promise<T>,
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cacheFn: () => Promise<T>,
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): Promise<T> {
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if (!navigator.onLine) return cacheFn()
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try {
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return await onlineFn()
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} catch (err) {
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if (isNetworkError(err)) return cacheFn()
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throw err
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}
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}
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