📄 tanstack/query/latest/docs/reference/QueryCache

import { QueryCache } from '@tanstack/react-query'

const queryCache = new QueryCache({
  onError: (error) => {
    console.log(error)
  },
  onSuccess: (data) => {
    console.log(data)
  },
  onSettled: (data, error) => {
    console.log(data, error)
  },
})

const query = queryCache.find(['posts'])


import { QueryCache } from '@tanstack/react-query'

const queryCache = new QueryCache({
  onError: (error) => {
    console.log(error)
  },
  onSuccess: (data) => {
    console.log(data)
  },
  onSettled: (data, error) => {
    console.log(data, error)
  },
})

const query = queryCache.find(['posts'])

Its available methods are:

Options

onError?: (error: unknown, query: Query) => void
- Optional
- This function will be called if some query encounters an error.
onSuccess?: (data: unknown, query: Query) => void
- Optional
- This function will be called if some query is successful.
onSettled?: (data: unknown | undefined, error: unknown | null, query: Query) => void
- Optional
- This function will be called if some query is settled (either successful or errored).

queryCache.find
---------------

find is a slightly more advanced synchronous method that can be used to get an existing query instance from the cache. This instance not only contains all the state for the query, but all of the instances, and underlying guts of the query as well. If the query does not exist, undefined will be returned.

Note: This is not typically needed for most applications, but can come in handy when needing more information about a query in rare scenarios (eg. Looking at the query.state.dataUpdatedAt timestamp to decide whether a query is fresh enough to be used as an initial value)

tsx

const query = queryCache.find(queryKey)


const query = queryCache.find(queryKey)

Options

filters?: QueryFilters: Query Filters

Returns

Query
- The query instance from the cache

queryCache.findAll
------------------

findAll is even more advanced synchronous method that can be used to get existing query instances from the cache that partially match query key. If queries do not exist, empty array will be returned.

Note: This is not typically needed for most applications, but can come in handy when needing more information about a query in rare scenarios

tsx

const queries = queryCache.findAll(queryKey)


const queries = queryCache.findAll(queryKey)

Options

queryKey?: QueryKey: Query Keys
filters?: QueryFilters: Query Filters

Returns

Query[]
- Query instances from the cache

queryCache.subscribe
--------------------

The subscribe method can be used to subscribe to the query cache as a whole and be informed of safe/known updates to the cache like query states changing or queries being updated, added or removed

tsx

const callback = (event) => {
  console.log(event.type, event.query)
}

const unsubscribe = queryCache.subscribe(callback)


const callback = (event) => {
  console.log(event.type, event.query)
}

const unsubscribe = queryCache.subscribe(callback)

Options

callback: (event: QueryCacheNotifyEvent) => void
- This function will be called with the query cache any time it is updated via its tracked update mechanisms (eg, query.setState, queryClient.removeQueries, etc). Out of scope mutations to the cache are not encouraged and will not fire subscription callbacks

Returns

unsubscribe: Function => void
- This function will unsubscribe the callback from the query cache.

queryCache.clear
----------------

The clear method can be used to clear the cache entirely and start fresh.

tsx

queryCache.clear()


queryCache.clear()