QueryClient

QueryClient

The QueryClient can be used to interact with a cache:

1 import { QueryClient } from '@sveltestack/svelte-query'
2 
3 const queryClient = new QueryClient({
4   defaultOptions: {
5     queries: {
6       staleTime: Infinity,
7     },
8   },
9 })
10 
11 await queryClient.prefetchQuery('posts', fetchPosts)

Its available methods are:

• fetchQuery
• fetchInfiniteQuery
• prefetchQuery
• prefetchInfiniteQuery
• getQueryData
• setQueryData
• getQueryState
• invalidateQueries
• refetchQueries
• cancelQueries
• removeQueries
• resetQueries
• isFetching
• getDefaultOptions
• setDefaultOptions
• getQueryDefaults
• setQueryDefaults
• getMutationDefaults
• setMutationDefaults
• getQueryCache
• getMutationCache
• clear

Options

• queryCache?: QueryCache
  • Optional
  • The query cache this client is connected to.
• mutationCache?: MutationCache
  • Optional
  • The mutation cache this client is connected to.
• defaultOptions?: DefaultOptions
  • Optional
  • Define defaults for all queries and mutations using this queryClient.

queryClient.fetchQuery

fetchQuery is an asynchronous method that can be used to fetch and cache a query. It will either resolve with the data or throw with the error. Use the prefetchQuery method if you just want to fetch a query without needing the result.

If the query exists and the data is not invalidated or older than the given staleTime, then the data from the cache will be returned. Otherwise it will try to fetch the latest data.

The difference between using fetchQuery and setQueryData is that fetchQuery is async and will ensure that duplicate requests for this query are not created with useQuery instances for the same query are rendered while the data is fetching.

1 try {
2   const data = await queryClient.fetchQuery(queryKey, queryFn)
3 } catch (error) {
4   console.log(error)
5 }

Specify a staleTime to only fetch when the data is older than a certain amount of time:

1 try {
2   const data = await queryClient.fetchQuery(queryKey, queryFn, {
3     staleTime: 10000,
4   })
5 } catch (error) {
6   console.log(error)
7 }

Options

The options for fetchQuery are exactly the same as those of useQuery, except the following: enabled, refetchInterval, refetchIntervalInBackground, refetchOnWindowFocus, refetchOnReconnect, notifyOnChangeProps, notifyOnChangePropsExclusions, onSuccess, onError, onSettled, useErrorBoundary, select, suspense, keepPreviousData, placeholderData; which are stictly for useQuery and useInfiniteQuery. You can check the source code for more clarity.

Returns

• Promise<TData>

queryClient.fetchInfiniteQuery

fetchInfiniteQuery is similar to fetchQuery but can be used to fetch and cache an infinite query.

1 try {
2   const data = await queryClient.fetchInfiniteQuery(queryKey, queryFn)
3   console.log(data.pages)
4 } catch (error) {
5   console.log(error)
6 }

Options

The options for fetchInfiniteQuery are exactly the same as those of fetchQuery.

Returns

• Promise<InfiniteData<TData>>

queryClient.prefetchQuery

prefetchQuery is an asynchronous method that can be used to prefetch a query before it is needed or rendered with useQuery and friends. The method works the same as fetchQuery except that is will not throw or return any data.

 await queryClient.prefetchQuery(queryKey, queryFn)

You can even use it with a default queryFn in your config!

 await queryClient.prefetchQuery(queryKey)

Options

The options for prefetchQuery are exactly the same as those of fetchQuery.

Returns

• Promise<void>
  • A promise is returned that will either immediately resolve if no fetch is needed or after the query has been executed. It will not return any data or throw any errors.

queryClient.prefetchInfiniteQuery

prefetchInfiniteQuery is similar to prefetchQuery but can be used to prefetch and cache an infinite query.

 await queryClient.prefetchInfiniteQuery(queryKey, queryFn)

Options

The options for prefetchInfiniteQuery are exactly the same as those of fetchQuery.

Returns

• Promise<void>
  • A promise is returned that will either immediately resolve if no fetch is needed or after the query has been executed. It will not return any data or throw any errors.

queryClient.getQueryData

getQueryData is a synchronous function that can be used to get an existing query's cached data. If the query does not exist, undefined will be returned.

 const data = queryClient.getQueryData(queryKey)

Options

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

Returns

• data: TData | undefined
  • The data for the cached query, or undefined if the query does not exist.

queryClient.setQueryData

setQueryData is a synchronous function that can be used to immediately update a query's cached data. If the query does not exist, it will be created. If the query is not utilized by a query hook in the default cacheTime of 5 minutes, the query will be garbage collected.

The difference between using setQueryData and fetchQuery is that setQueryData is sync and assumes that you already synchronously have the data available. If you need to fetch the data asynchronously, it's suggested that you either refetch the query key or use fetchQuery to handle the asynchronous fetch.

 queryClient.setQueryData(queryKey, updater)

Options

• queryKey: QueryKey: Query Keys
• updater: unknown | (oldData: TData | undefined) => TData
  • If non-function is passed, the data will be updated to this value
  • If a function is passed, it will receive the old data value and be expected to return a new one.

Using an updater value

 setQueryData(queryKey, newData)

Using an updater function

For convenience in syntax, you can also pass an updater function which receives the current data value and returns the new one:

 setQueryData(queryKey, oldData => newData)

queryClient.getQueryState

getQueryState is a synchronous function that can be used to get an existing query's state. If the query does not exist, undefined will be returned.

1 const state = queryClient.getQueryState(queryKey)
2 console.log(state.dataUpdatedAt)

Options

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

queryClient.invalidateQueries

The invalidateQueries method can be used to invalidate and refetch single or multiple queries in the cache based on their query keys or any other functionally accessible property/state of the query. By default, all matching queries are immediately marked as invalid and active queries are refetched in the background.

• If you do not want active queries to refetch, and simply be marked as invalid, you can use the refetchActive: false option.
• If you want inactive queries to refetch as well, use the refetchInactive: true option

1 await queryClient.invalidateQueries('posts', {
2   exact,
3   refetchActive: true,
4   refetchInactive: false
5 }, { throwOnError })

Options

• queryKey?: QueryKey: Query Keys
• filters?: QueryFilters: Query Filters
  • refetchActive: Boolean
    • Defaults to true
    • When set to false, queries that match the refetch predicate and are actively being rendered via useQuery and friends will NOT be refetched in the background, and only marked as invalid.
  • refetchInactive: Boolean
    • Defaults to false
    • When set to true, queries that match the refetch predicate and are not being rendered via useQuery and friends will be both marked as invalid and also refetched in the background
• refetchOptions?: RefetchOptions:
  • throwOnError?: boolean
    • When set to true, this method will throw if any of the query refetch tasks fail.

queryClient.refetchQueries

The refetchQueries method can be used to refetch queries based on certain conditions.

Examples:

1 // refetch all queries:
2 await queryClient.refetchQueries()
3 
4 // refetch all stale queries:
5 await queryClient.refetchQueries({ stale: true })
6 
7 // refetch all active queries partially matching a query key:
8 await queryClient.refetchQueries(['posts'], { active: true })
9 
10 // refetch all active queries exactly matching a query key:
11 await queryClient.refetchQueries(['posts', 1], { active: true, exact: true })

Options

• queryKey?: QueryKey: Query Keys
• filters?: QueryFilters: Query Filters
• refetchOptions?: RefetchOptions:
  • throwOnError?: boolean
    • When set to true, this method will throw if any of the query refetch tasks fail.

Returns

This function returns a promise that will resolve when all of the queries are done being refetched. By default, it will not throw an error if any of those queries refetches fail, but this can be configured by setting the throwOnError option to true

queryClient.cancelQueries

The cancelQueries method can be used to cancel outgoing queries based on their query keys or any other functionally accessible property/state of the query.

This is most useful when performing optimistic updates since you will likely need to cancel any outgoing query refetches so they don't clobber your optimistic update when they resolve.

 await queryClient.cancelQueries('posts', { exact: true })

Options

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

Returns

This method does not return anything

queryClient.removeQueries

The removeQueries method can be used to remove queries from the cache based on their query keys or any other functionally accessible property/state of the query.

 queryClient.removeQueries(queryKey, { exact: true })

Options

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

Returns

This method does not return anything

queryClient.resetQueries

The resetQueries method can be used to reset queries in the cache to their initial state based on their query keys or any other functionally accessible property/state of the query.

This will notify subscribers — unlike clear, which removes all subscribers — and reset the query to its pre-loaded state — unlike invalidateQueries. If a query has initialData, the query's data will be reset to that. If a query is active, it will be refetched.

 queryClient.resetQueries(queryKey, { exact: true })

Options

• queryKey?: QueryKey: Query Keys
• filters?: QueryFilters: Query Filters
• resetOptions?: ResetOptions:
  • throwOnError?: boolean
    • When set to true, this method will throw if any of the query refetch tasks fail.

Returns

This method returns a promise that resolves when all active queries have been refetched.

queryClient.isFetching

This isFetching method returns an integer representing how many queries, if any, in the cache are currently fetching (including background-fetching, loading new pages, or loading more infinite query results)

1 if (queryClient.isFetching()) {
2   console.log('At least one query is fetching!')
3 }

Svelte Query also exports a handy useIsFetching hook that will let you subscribe to this state in your components without creating a manual subscription to the query cache.

Options

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

Returns

This method returns the number of fetching queries.

queryClient.getDefaultOptions

The getDefaultOptions method returns the default options which have been set when creating the client or with setDefaultOptions.

 const defaultOptions = queryClient.getDefaultOptions()

queryClient.setDefaultOptions

The setDefaultOptions method can be used to dynamically set the default options for this queryClient.

1 queryClient.setDefaultOptions({
2   queries: {
3     staleTime: Infinity,
4   },
5 })

queryClient.getQueryDefaults

The getQueryDefaults method returns the default options which have been set for specific queries:

 const defaultOptions = queryClient.getQueryDefaults('posts')

queryClient.setQueryDefaults

setQueryDefaults can be used to set default options for specific queries:

1 queryClient.setQueryDefaults('posts', { queryFn: fetchPosts })
2 
3 function Component() {
4   const { data } = useQuery('posts')
5 }

Options

• queryKey: QueryKey: Query Keys
• options: QueryOptions

queryClient.getMutationDefaults

The getMutationDefaults method returns the default options which have been set for specific mutations:

 const defaultOptions = queryClient.getMutationDefaults('addPost')

queryClient.setMutationDefaults

setMutationDefaults can be used to set default options for specific mutations:

1 queryClient.setMutationDefaults('addPost', { mutationFn: addPost })
2 
3 function Component() {
4   const { data } = useMutation('addPost')
5 }

Options

• mutationKey: string | unknown[]
• options: MutationOptions

queryClient.getQueryCache

The getQueryCache method returns the query cache this client is connected to.

 const queryCache = queryClient.getQueryCache()

queryClient.getMutationCache

The getMutationCache method returns the mutation cache this client is connected to.

 const mutationCache = queryClient.getMutationCache()

queryClient.clear

The clear method clears all connected caches.

 queryClient.clear()