feat(svelte-query): use store for reactivity in options

docs/svelte/overview.md

@@ -71,4 +71,4 @@ Svelte Query offers useful functions and components that will make managing serv
 Svelte Query offers an API similar to React Query, but there are some key differences to be mindful of.
 
 - Many of the functions in Svelte Query return a Svelte store. To access values on these stores reactively, you need to prefix the store with a `$`. You can learn more about Svelte stores [here](https://svelte.dev/tutorial/writable-stores).
-- If your query or mutation depends on variables, you must assign it reactively. You can read more about this [here](./reactivity).
+- If your query or mutation depends on variables, you must use a store for the options. You can read more about this [here](./reactivity).

docs/svelte/reactivity.md

@@ -3,12 +3,12 @@ id: reactivity
 title: Reactivity
 ---
 
-Svelte uses a compiler to build your code which optimises rendering. By default, variables will run once, unless they are referenced in your markup. To make a different variable or function reactive, you need to use [reactive declarations](https://svelte.dev/tutorial/reactive-declarations). This also applies to Svelte Query.
+Svelte uses a compiler to build your code which optimises rendering. By default, variables will run once, unless they are referenced in your markup. To be able to react to changes in options you need to use [stores](https://svelte.dev/tutorial/writable-stores).
 
 In the below example, the `refetchInterval` option is set from the variable `intervalMs`, which is edited by the input field. However, as the query is not told it should react to changes in `intervalMs`, `refetchInterval` will not change when the input value changes.
 
 ```markdown
-<script lang="ts">
+<script>
   import { createQuery } from '@tanstack/svelte-query'
 
   let intervalMs = 1000
@@ -25,22 +25,25 @@ In the below example, the `refetchInterval` option is set from the variable `int
 <input bind:value={intervalMs} type="number" />
 ```
 
-To solve this, you can prefix the query with `$: ` to tell the compiler it should be reactive.
+To solve this, create a store for the options and use it as input for the query. Update the options store when the value changes and the query will react to the change.
 
 ```markdown
-<script lang="ts">
+<script>
   import { createQuery } from '@tanstack/svelte-query'
 
-  let intervalMs = 1000
-
   const endpoint = 'http://localhost:5173/api/data'
 
-  $: query = createQuery({
+  const queryOptions = writable({
     queryKey: ['refetch'],
     queryFn: async () => await fetch(endpoint).then((r) => r.json()),
-    refetchInterval: intervalMs,
+    refetchInterval: 1000,
   })
+  const query = createQuery(queryOptions)
+
+  function updateRefetchInterval(event) {
+    $queryOptions.refetchInterval = event.target.valueAsNumber
+  }
 </script>
 
-<input bind:value={intervalMs} type="number" />
+<input type="number" on:input={updateRefetchInterval} />
 ```

packages/svelte-query/src/__tests__/CreateQueries.svelte

@@ -3,7 +3,7 @@
   import { setQueryClientContext } from '../context'
   import type { QueriesOptions } from '../createQueries'
 
-  export let options: { queries: readonly [...QueriesOptions<any>] }
+  export let options: { queries: [...QueriesOptions<any>] }
 
   const queryClient = new QueryClient()
   setQueryClientContext(queryClient)

packages/svelte-query/src/__tests__/CreateQuery.svelte

@@ -1,8 +1,8 @@
 <script lang="ts">
-  import { createQuery, QueryClient, type CreateQueryOptions } from '../index'
+  import { createQuery, QueryClient, type CreateQueryOptions, type WritableOrVal } from '../index'
   import { setQueryClientContext } from '../context'
 
-  export let options: CreateQueryOptions<any>
+  export let options: WritableOrVal<CreateQueryOptions<any>>
 
   const queryClient = new QueryClient()
   setQueryClientContext(queryClient)
@@ -17,3 +17,9 @@
 {:else if $query.isSuccess}
   <p>Success</p>
 {/if}
+
+<ul>
+  {#each $query.data ?? [] as entry}
+    <li>id: {entry.id}</li>
+  {/each}
+</ul>

packages/svelte-query/src/__tests__/createQuery.test.ts

@@ -1,7 +1,9 @@
 import { describe, it, expect } from 'vitest'
 import { render, waitFor } from '@testing-library/svelte'
+import { writable } from 'svelte/store'
 import CreateQuery from './CreateQuery.svelte'
 import { sleep } from './utils'
+import type { CreateQueryOptions, WritableOrVal } from '../types'
 
 describe('createQuery', () => {
   it('Render and wait for success', async () => {
@@ -25,4 +27,38 @@ describe('createQuery', () => {
       expect(rendered.getByText('Success')).toBeInTheDocument()
     })
   })
+
+  it('should keep previous data when returned as placeholder data', async () => {
+    const options: WritableOrVal<CreateQueryOptions> = writable({
+      queryKey: ['test', [1]],
+      queryFn: async ({ queryKey }) => {
+        await sleep(50)
+        const ids = queryKey[1]
+        if (!ids || !Array.isArray(ids)) return []
+        return ids.map((id) => ({ id }))
+      },
+      placeholderData: (previousData: { id: number }[]) => previousData,
+    })
+    const rendered = render(CreateQuery, { props: { options } })
+
+    expect(rendered.queryByText('id: 1')).not.toBeInTheDocument()
+    expect(rendered.queryByText('id: 2')).not.toBeInTheDocument()
+
+    await sleep(100)
+
+    expect(rendered.queryByText('id: 1')).toBeInTheDocument()
+    expect(rendered.queryByText('id: 2')).not.toBeInTheDocument()
+
+    options.update((o) => ({ ...o, queryKey: ['test', [1, 2]] }))
+
+    await sleep(0)
+
+    expect(rendered.queryByText('id: 1')).toBeInTheDocument()
+    expect(rendered.queryByText('id: 2')).not.toBeInTheDocument()
+
+    await sleep(100)
+
+    expect(rendered.queryByText('id: 1')).toBeInTheDocument()
+    expect(rendered.queryByText('id: 2')).toBeInTheDocument()
+  })
 })

packages/svelte-query/src/createBaseQuery.ts

@@ -1,8 +1,13 @@
 import type { QueryClient, QueryKey, QueryObserver } from '@tanstack/query-core'
 import { notifyManager } from '@tanstack/query-core'
-import type { CreateBaseQueryOptions, CreateBaseQueryResult } from './types'
+import type {
+  CreateBaseQueryOptions,
+  CreateBaseQueryResult,
+  WritableOrVal,
+} from './types'
 import { useQueryClient } from './useQueryClient'
-import { derived, readable } from 'svelte/store'
+import { derived, get, readable, writable } from 'svelte/store'
+import { isWritable } from './utils'
 
 export function createBaseQuery<
   TQueryFnData,
@@ -11,61 +16,63 @@ export function createBaseQuery<
   TQueryData,
   TQueryKey extends QueryKey,
 >(
-  options: CreateBaseQueryOptions<
-    TQueryFnData,
-    TError,
-    TData,
-    TQueryData,
-    TQueryKey
+  options: WritableOrVal<
+    CreateBaseQueryOptions<TQueryFnData, TError, TData, TQueryData, TQueryKey>
   >,
   Observer: typeof QueryObserver,
   queryClient?: QueryClient,
 ): CreateBaseQueryResult<TData, TError> {
   const client = useQueryClient(queryClient)
-  const defaultedOptions = client.defaultQueryOptions(options)
-  defaultedOptions._optimisticResults = 'optimistic'
 
-  let observer = new Observer<
+  const optionsStore = isWritable(options) ? options : writable(options)
+
+  const defaultedOptionsStore = derived(optionsStore, ($options) => {
+    const defaultedOptions = client.defaultQueryOptions($options)
+    defaultedOptions._optimisticResults = 'optimistic'
+
+    // Include callbacks in batch renders
+    if (defaultedOptions.onError) {
+      defaultedOptions.onError = notifyManager.batchCalls(
+        defaultedOptions.onError,
+      )
+    }
+
+    if (defaultedOptions.onSuccess) {
+      defaultedOptions.onSuccess = notifyManager.batchCalls(
+        defaultedOptions.onSuccess,
+      )
+    }
+
+    if (defaultedOptions.onSettled) {
+      defaultedOptions.onSettled = notifyManager.batchCalls(
+        defaultedOptions.onSettled,
+      )
+    }
+
+    return defaultedOptions
+  })
+
+  const observer = new Observer<
     TQueryFnData,
     TError,
     TData,
     TQueryData,
     TQueryKey
-  >(client, defaultedOptions)
-
-  // Include callbacks in batch renders
-  if (defaultedOptions.onError) {
-    defaultedOptions.onError = notifyManager.batchCalls(
-      defaultedOptions.onError,
-    )
-  }
-
-  if (defaultedOptions.onSuccess) {
-    defaultedOptions.onSuccess = notifyManager.batchCalls(
-      defaultedOptions.onSuccess,
-    )
-  }
-
-  if (defaultedOptions.onSettled) {
-    defaultedOptions.onSettled = notifyManager.batchCalls(
-      defaultedOptions.onSettled,
-    )
-  }
+  >(client, get(defaultedOptionsStore))
 
-  readable(observer).subscribe(($observer) => {
-    observer = $observer
+  defaultedOptionsStore.subscribe(($defaultedOptions) => {
     // Do not notify on updates because of changes in the options because
     // these changes should already be reflected in the optimistic result.
-    observer.setOptions(defaultedOptions, { listeners: false })
+    observer.setOptions($defaultedOptions, { listeners: false })
   })
 
   const result = readable(observer.getCurrentResult(), (set) => {
     return observer.subscribe(notifyManager.batchCalls(set))
   })
 
   const { subscribe } = derived(result, ($result) => {
-    $result = observer.getOptimisticResult(defaultedOptions)
-    return !defaultedOptions.notifyOnChangeProps
+    $result = observer.getOptimisticResult(get(defaultedOptionsStore))
+    return !get(defaultedOptionsStore).notifyOnChangeProps
       ? observer.trackResult($result)
       : $result
   })

packages/svelte-query/src/createInfiniteQuery.ts

@@ -8,6 +8,7 @@ import { InfiniteQueryObserver } from '@tanstack/query-core'
 import type {
   CreateInfiniteQueryOptions,
   CreateInfiniteQueryResult,
+  WritableOrVal,
 } from './types'
 import { createBaseQuery } from './createBaseQuery'
 
@@ -17,12 +18,14 @@ export function createInfiniteQuery<
   TData = TQueryFnData,
   TQueryKey extends QueryKey = QueryKey,
 >(
-  options: CreateInfiniteQueryOptions<
-    TQueryFnData,
-    TError,
-    TData,
-    TQueryFnData,
-    TQueryKey
+  options: WritableOrVal<
+    CreateInfiniteQueryOptions<
+      TQueryFnData,
+      TError,
+      TData,
+      TQueryFnData,
+      TQueryKey
+    >
   >,
   queryClient?: QueryClient,
 ): CreateInfiniteQueryResult<TData, TError> {

packages/svelte-query/src/createMutation.ts

@@ -1,35 +1,41 @@
-import { readable, derived } from 'svelte/store'
+import { readable, derived, writable, get } from 'svelte/store'
 import type { QueryClient, RegisteredError } from '@tanstack/query-core'
 import { MutationObserver, notifyManager } from '@tanstack/query-core'
 import type {
   CreateMutateFunction,
   CreateMutationOptions,
   CreateMutationResult,
+  WritableOrVal,
 } from './types'
 import { useQueryClient } from './useQueryClient'
+import { isWritable } from './utils'
 
 export function createMutation<
   TData = unknown,
   TError = RegisteredError,
   TVariables = void,
   TContext = unknown,
 >(
-  options: CreateMutationOptions<TData, TError, TVariables, TContext>,
+  options: WritableOrVal<
+    CreateMutationOptions<TData, TError, TVariables, TContext>
+  >,
   queryClient?: QueryClient,
 ): CreateMutationResult<TData, TError, TVariables, TContext> {
   const client = useQueryClient(queryClient)
-  let observer = new MutationObserver<TData, TError, TVariables, TContext>(
+
+  const optionsStore = isWritable(options) ? options : writable(options)
+
+  const observer = new MutationObserver<TData, TError, TVariables, TContext>(
     client,
-    options,
+    get(optionsStore),
   )
   let mutate: CreateMutateFunction<TData, TError, TVariables, TContext>
 
-  readable(observer).subscribe(($observer) => {
-    observer = $observer
+  optionsStore.subscribe(($options) => {
     mutate = (variables, mutateOptions) => {
       observer.mutate(variables, mutateOptions).catch(noop)
     }
-    observer.setOptions(options)
+    observer.setOptions($options)
   })
 
   const result = readable(observer.getCurrentResult(), (set) => {

packages/svelte-query/src/createQueries.ts

@@ -8,10 +8,11 @@ import type {
 } from '@tanstack/query-core'
 
 import { notifyManager, QueriesObserver } from '@tanstack/query-core'
-import { readable, type Readable } from 'svelte/store'
+import { derived, get, readable, writable, type Readable } from 'svelte/store'
 
-import type { CreateQueryOptions } from './types'
+import type { CreateQueryOptions, WritableOrVal } from './types'
 import { useQueryClient } from './useQueryClient'
+import { isWritable } from './utils'
 
 // This defines the `CreateQueryOptions` that are accepted in `QueriesOptions` & `GetOptions`.
 // `placeholderData` function does not have a parameter
@@ -155,34 +156,33 @@ export function createQueries<T extends any[]>({
   queries,
   queryClient,
 }: {
-  queries: readonly [...QueriesOptions<T>]
+  queries: WritableOrVal<[...QueriesOptions<T>]>
   queryClient?: QueryClient
 }): CreateQueriesResult<T> {
   const client = useQueryClient(queryClient)
   // const isRestoring = useIsRestoring()
 
-  function getDefaultQuery(newQueries: readonly [...QueriesOptions<T>]) {
-    return newQueries.map((options) => {
+  const queriesStore = isWritable(queries) ? queries : writable(queries)
+
+  const defaultedQueriesStore = derived(queriesStore, ($queries) => {
+    return $queries.map((options) => {
       const defaultedOptions = client.defaultQueryOptions(options)
       // Make sure the results are already in fetching state before subscribing or updating options
       defaultedOptions._optimisticResults = 'optimistic'
 
       return defaultedOptions
     })
-  }
-
-  const defaultedQueries = getDefaultQuery(queries)
-  let observer = new QueriesObserver(client, defaultedQueries)
+  })
+  const observer = new QueriesObserver(client, get(defaultedQueriesStore))
 
-  readable(observer).subscribe(($observer) => {
-    observer = $observer
+  defaultedQueriesStore.subscribe(($defaultedQueries) => {
     // Do not notify on updates because of changes in the options because
     // these changes should already be reflected in the optimistic result.
-    observer.setQueries(defaultedQueries, { listeners: false })
+    observer.setQueries($defaultedQueries, { listeners: false })
   })
 
   const { subscribe } = readable(
-    observer.getOptimisticResult(defaultedQueries) as any,
+    observer.getOptimisticResult(get(defaultedQueriesStore)) as any,
     (set) => {
       return observer.subscribe(notifyManager.batchCalls(set))
     },