react-query/packages/query-persist-client-core/src/createPersister.ts

import { hashKey, matchQuery, partialMatchKey } from '@tanstack/query-core'
import type {
  Query,
  QueryClient,
  QueryFilters,
  QueryFunctionContext,
  QueryKey,
  QueryState,
} from '@tanstack/query-core'

export interface PersistedQuery {
  buster: string
  queryHash: string
  queryKey: QueryKey
  state: QueryState
}

export type MaybePromise<T> = T | Promise<T>

export interface AsyncStorage<TStorageValue = string> {
  getItem: (key: string) => MaybePromise<TStorageValue | undefined | null>
  setItem: (key: string, value: TStorageValue) => MaybePromise<unknown>
  removeItem: (key: string) => MaybePromise<void>
  entries?: () => MaybePromise<Array<[key: string, value: TStorageValue]>>
}

export interface StoragePersisterOptions<TStorageValue = string> {
  /** The storage client used for setting and retrieving items from cache.
   * For SSR pass in `undefined`.
   */
  storage: AsyncStorage<TStorageValue> | undefined | null
  /**
   * How to serialize the data to storage.
   * @default `JSON.stringify`
   */
  serialize?: (persistedQuery: PersistedQuery) => MaybePromise<TStorageValue>
  /**
   * How to deserialize the data from storage.
   * @default `JSON.parse`
   */
  deserialize?: (cachedString: TStorageValue) => MaybePromise<PersistedQuery>
  /**
   * A unique string that can be used to forcefully invalidate existing caches,
   * if they do not share the same buster string
   */
  buster?: string
  /**
   * The max-allowed age of the cache in milliseconds.
   * If a persisted cache is found that is older than this
   * time, it will be discarded
   * @default 24 hours
   */
  maxAge?: number
  /**
   * Prefix to be used for storage key.
   * Storage key is a combination of prefix and query hash in a form of `prefix-queryHash`.
   * @default 'tanstack-query'
   */
  prefix?: string
  /**
   * Filters to narrow down which Queries should be persisted.
   */
  filters?: QueryFilters
}

export const PERSISTER_KEY_PREFIX = 'tanstack-query'

/**
 * Warning: experimental feature.
 * This utility function enables fine-grained query persistence.
 * Simple add it as a `persister` parameter to `useQuery` or `defaultOptions` on `queryClient`.
 *
 * ```
 * useQuery({
     queryKey: ['myKey'],
     queryFn: fetcher,
     persister: createPersister({
       storage: localStorage,
     }),
   })
   ```
 */
export function experimental_createQueryPersister<TStorageValue = string>({
  storage,
  buster = '',
  maxAge = 1000 * 60 * 60 * 24,
  serialize = JSON.stringify as Required<
    StoragePersisterOptions<TStorageValue>
  >['serialize'],
  deserialize = JSON.parse as Required<
    StoragePersisterOptions<TStorageValue>
  >['deserialize'],
  prefix = PERSISTER_KEY_PREFIX,
  filters,
}: StoragePersisterOptions<TStorageValue>) {
  function isExpiredOrBusted(persistedQuery: PersistedQuery) {
    if (persistedQuery.state.dataUpdatedAt) {
      const queryAge = Date.now() - persistedQuery.state.dataUpdatedAt
      const expired = queryAge > maxAge
      const busted = persistedQuery.buster !== buster

      if (expired || busted) {
        return true
      }

      return false
    }

    return true
  }

  async function retrieveQuery<T>(
    queryHash: string,
    afterRestoreMacroTask?: (persistedQuery: PersistedQuery) => void,
  ) {
    if (storage != null) {
      const storageKey = `${prefix}-${queryHash}`
      try {
        const storedData = await storage.getItem(storageKey)
        if (storedData) {
          const persistedQuery = await deserialize(storedData)

          if (isExpiredOrBusted(persistedQuery)) {
            await storage.removeItem(storageKey)
          } else {
            if (afterRestoreMacroTask) {
              // Just after restoring we want to get fresh data from the server if it's stale
              setTimeout(() => afterRestoreMacroTask(persistedQuery), 0)
            }
            // We must resolve the promise here, as otherwise we will have `loading` state in the app until `queryFn` resolves
            return persistedQuery.state.data as T
          }
        }
      } catch (err) {
        if (process.env.NODE_ENV === 'development') {
          console.error(err)
          console.warn(
            'Encountered an error attempting to restore query cache from persisted location.',
          )
        }
        await storage.removeItem(storageKey)
      }
    }

    return
  }

  async function persistQueryByKey(
    queryKey: QueryKey,
    queryClient: QueryClient,
  ) {
    if (storage != null) {
      const query = queryClient.getQueryCache().find({ queryKey })
      if (query) {
        await persistQuery(query)
      } else {
        if (process.env.NODE_ENV === 'development') {
          console.warn(
            'Could not find query to be persisted. QueryKey:',
            JSON.stringify(queryKey),
          )
        }
      }
    }
  }

  async function persistQuery(query: Query) {
    if (storage != null) {
      const storageKey = `${prefix}-${query.queryHash}`
      storage.setItem(
        storageKey,
        await serialize({
          state: query.state,
          queryKey: query.queryKey,
          queryHash: query.queryHash,
          buster: buster,
        }),
      )
    }
  }

  async function persisterFn<T, TQueryKey extends QueryKey>(
    queryFn: (context: QueryFunctionContext<TQueryKey>) => T | Promise<T>,
    ctx: QueryFunctionContext<TQueryKey>,
    query: Query,
  ) {
    const matchesFilter = filters ? matchQuery(filters, query) : true

    // Try to restore only if we do not have any data in the cache and we have persister defined
    if (matchesFilter && query.state.data === undefined && storage != null) {
      const restoredData = await retrieveQuery(
        query.queryHash,
        (persistedQuery: PersistedQuery) => {
          // Set proper updatedAt, since resolving in the first pass overrides those values
          query.setState({
            dataUpdatedAt: persistedQuery.state.dataUpdatedAt,
            errorUpdatedAt: persistedQuery.state.errorUpdatedAt,
          })

          if (query.isStale()) {
            query.fetch()
          }
        },
      )

      if (restoredData != null) {
        return Promise.resolve(restoredData as T)
      }
    }

    // If we did not restore, or restoration failed - fetch
    const queryFnResult = await queryFn(ctx)

    if (matchesFilter && storage != null) {
      // Persist if we have storage defined, we use timeout to get proper state to be persisted
      setTimeout(() => {
        persistQuery(query)
      }, 0)
    }

    return Promise.resolve(queryFnResult)
  }

  async function persisterGc() {
    if (storage?.entries) {
      const entries = await storage.entries()
      for (const [key, value] of entries) {
        if (key.startsWith(prefix)) {
          const persistedQuery = await deserialize(value)

          if (isExpiredOrBusted(persistedQuery)) {
            await storage.removeItem(key)
          }
        }
      }
    } else if (process.env.NODE_ENV === 'development') {
      throw new Error(
        'Provided storage does not implement `entries` method. Garbage collection is not possible without ability to iterate over storage items.',
      )
    }
  }

  async function restoreQueries(
    queryClient: QueryClient,
    filters: Pick<QueryFilters, 'queryKey' | 'exact'> = {},
  ): Promise<void> {
    const { exact, queryKey } = filters

    if (storage?.entries) {
      const entries = await storage.entries()
      for (const [key, value] of entries) {
        if (key.startsWith(prefix)) {
          const persistedQuery = await deserialize(value)

          if (isExpiredOrBusted(persistedQuery)) {
            await storage.removeItem(key)
            continue
          }

          if (queryKey) {
            if (exact) {
              if (persistedQuery.queryHash !== hashKey(queryKey)) {
                continue
              }
            } else if (!partialMatchKey(persistedQuery.queryKey, queryKey)) {
              continue
            }
          }

          queryClient.setQueryData(
            persistedQuery.queryKey,
            persistedQuery.state.data,
            {
              updatedAt: persistedQuery.state.dataUpdatedAt,
            },
          )
        }
      }
    } else if (process.env.NODE_ENV === 'development') {
      throw new Error(
        'Provided storage does not implement `entries` method. Restoration of all stored entries is not possible without ability to iterate over storage items.',
      )
    }
  }

  return {
    persisterFn,
    persistQuery,
    persistQueryByKey,
    retrieveQuery,
    persisterGc,
    restoreQueries,
  }
}