Function makeQueryResultHandler

packages/query-db-collection/src/query.ts:1354–1403

(queryKey: QueryKey)

    // eslint-disable-next-line no-shadow
    const makeQueryResultHandler = (queryKey: QueryKey) => {
      const hashedQueryKey = hashKey(queryKey)
      const handleQueryResult: UpdateHandler = (result) => {
        if (result.isSuccess) {
          // Skip processing this result while data refreshes are deferred.
          // Optimistic state covers the gap. Once the barrier resolves,
          // trigger a fresh refetch to get authoritative data.
          if (collection.deferDataRefresh) {
            collection.deferDataRefresh.then(() => {
              const observer = state.observers.get(hashedQueryKey)
              if (observer) {
                observer.refetch().catch(() => {
                  // Errors handled by the next handleQueryResult invocation
                })
              }
            })
            return
          }

          if (retainedQueriesPendingRevalidation.has(hashedQueryKey)) {
            void reconcileSuccessfulResult(queryKey, result).catch((error) => {
              console.error(
                `[QueryCollection] Error reconciling query ${String(queryKey)}:`,
                error,
              )
            })
          } else {
            applySuccessfulResult(queryKey, result)
          }
        } else if (result.isError) {
          const isNewError =
            result.errorUpdatedAt !== state.lastErrorUpdatedAt ||
            result.error !== state.lastError
          if (isNewError) {
            state.lastError = result.error
            state.errorCount++
            state.lastErrorUpdatedAt = result.errorUpdatedAt
          }

          console.error(
            `[QueryCollection] Error observing query ${String(queryKey)}:`,
            result.error,
          )

          // Mark collection as ready even on error to avoid blocking apps
          markReady()
        }
      }
      return handleQueryResult
    }

    const isSubscribed = (hashedQueryKey: string) => {
      return unsubscribes.has(hashedQueryKey)