Function: useLiveQuery()

Call Signature

function useLiveQuery<TContext>(queryFn, deps?): UseLiveQueryReturn<{ [K in string | number | symbol]: (TContext["result"] extends object ? any[any] : TContext["hasJoins"] extends true ? TContext["schema"] : TContext["schema"][TContext["fromSourceName"]])[K] }>;

function useLiveQuery<TContext>(queryFn, deps?): UseLiveQueryReturn<{ [K in string | number | symbol]: (TContext["result"] extends object ? any[any] : TContext["hasJoins"] extends true ? TContext["schema"] : TContext["schema"][TContext["fromSourceName"]])[K] }>;

Defined in: useLiveQuery.svelte.ts:155

Create a live query using a query function

Parameters

queryFn

(q) => QueryBuilder<TContext>

Query function that defines what data to fetch

deps?

() => unknown[]

Array of reactive dependencies that trigger query re-execution when changed

UseLiveQueryReturn<{ [K in string | number | symbol]: (TContext["result"] extends object ? any[any] : TContext["hasJoins"] extends true ? TContext["schema"] : TContext["schema"][TContext["fromSourceName"]])[K] }>

Reactive object with query data, state, and status information

Remarks

IMPORTANT - Destructuring in Svelte 5: Direct destructuring breaks reactivity. To destructure, wrap with $derived:

❌ Incorrect - Loses reactivity:

const { data, isLoading } = useLiveQuery(...)

const { data, isLoading } = useLiveQuery(...)

✅ Correct - Maintains reactivity:

// Option 1: Use dot notation (recommended)
const query = useLiveQuery(...)
// Access: query.data, query.isLoading

// Option 2: Wrap with $derived for destructuring
const query = useLiveQuery(...)
const { data, isLoading } = $derived(query)

// Option 1: Use dot notation (recommended)
const query = useLiveQuery(...)
// Access: query.data, query.isLoading

// Option 2: Wrap with $derived for destructuring
const query = useLiveQuery(...)
const { data, isLoading } = $derived(query)

This is a fundamental Svelte 5 limitation, not a library bug. See: https://github.com/sveltejs/svelte/issues/11002

Examples

// Basic query with object syntax (recommended pattern)
const todosQuery = useLiveQuery((q) =>
  q.from({ todos: todosCollection })
   .where(({ todos }) => eq(todos.completed, false))
   .select(({ todos }) => ({ id: todos.id, text: todos.text }))
)
// Access via: todosQuery.data, todosQuery.isLoading, etc.

// Basic query with object syntax (recommended pattern)
const todosQuery = useLiveQuery((q) =>
  q.from({ todos: todosCollection })
   .where(({ todos }) => eq(todos.completed, false))
   .select(({ todos }) => ({ id: todos.id, text: todos.text }))
)
// Access via: todosQuery.data, todosQuery.isLoading, etc.

// With reactive dependencies
let minPriority = $state(5)
const todosQuery = useLiveQuery(
  (q) => q.from({ todos: todosCollection })
         .where(({ todos }) => gt(todos.priority, minPriority)),
  [() => minPriority] // Re-run when minPriority changes
)

// With reactive dependencies
let minPriority = $state(5)
const todosQuery = useLiveQuery(
  (q) => q.from({ todos: todosCollection })
         .where(({ todos }) => gt(todos.priority, minPriority)),
  [() => minPriority] // Re-run when minPriority changes
)

// Destructuring with $derived (if needed)
const query = useLiveQuery((q) =>
  q.from({ todos: todosCollection })
)
const { data, isLoading, isError } = $derived(query)
// Now data, isLoading, and isError maintain reactivity

// Destructuring with $derived (if needed)
const query = useLiveQuery((q) =>
  q.from({ todos: todosCollection })
)
const { data, isLoading, isError } = $derived(query)
// Now data, isLoading, and isError maintain reactivity

// Join pattern
const issuesQuery = useLiveQuery((q) =>
  q.from({ issues: issueCollection })
   .join({ persons: personCollection }, ({ issues, persons }) =>
     eq(issues.userId, persons.id)
   )
   .select(({ issues, persons }) => ({
     id: issues.id,
     title: issues.title,
     userName: persons.name
   }))
)

// Join pattern
const issuesQuery = useLiveQuery((q) =>
  q.from({ issues: issueCollection })
   .join({ persons: personCollection }, ({ issues, persons }) =>
     eq(issues.userId, persons.id)
   )
   .select(({ issues, persons }) => ({
     id: issues.id,
     title: issues.title,
     userName: persons.name
   }))
)

// Handle loading and error states in template
const todosQuery = useLiveQuery((q) =>
  q.from({ todos: todoCollection })
)

// In template:
// {#if todosQuery.isLoading}
//   <div>Loading...</div>
// {:else if todosQuery.isError}
//   <div>Error: {todosQuery.status}</div>
// {:else}
//   <ul>
//     {#each todosQuery.data as todo (todo.id)}
//       <li>{todo.text}</li>
//     {/each}
//   </ul>
// {/if}

// Handle loading and error states in template
const todosQuery = useLiveQuery((q) =>
  q.from({ todos: todoCollection })
)

// In template:
// {#if todosQuery.isLoading}
//   <div>Loading...</div>
// {:else if todosQuery.isError}
//   <div>Error: {todosQuery.status}</div>
// {:else}
//   <ul>
//     {#each todosQuery.data as todo (todo.id)}
//       <li>{todo.text}</li>
//     {/each}
//   </ul>
// {/if}

Call Signature

function useLiveQuery<TContext>(queryFn, deps?): UseLiveQueryReturn<{ [K in string | number | symbol]: (TContext["result"] extends object ? any[any] : TContext["hasJoins"] extends true ? TContext["schema"] : TContext["schema"][TContext["fromSourceName"]])[K] }>;

function useLiveQuery<TContext>(queryFn, deps?): UseLiveQueryReturn<{ [K in string | number | symbol]: (TContext["result"] extends object ? any[any] : TContext["hasJoins"] extends true ? TContext["schema"] : TContext["schema"][TContext["fromSourceName"]])[K] }>;

Defined in: useLiveQuery.svelte.ts:161

Create a live query using a query function

Type Parameters

TContext

TContext extends Context

Parameters

queryFn

(q) => QueryBuilder<TContext> | null | undefined

Query function that defines what data to fetch

deps?

() => unknown[]

Array of reactive dependencies that trigger query re-execution when changed

Returns

Reactive object with query data, state, and status information

Remarks

IMPORTANT - Destructuring in Svelte 5: Direct destructuring breaks reactivity. To destructure, wrap with $derived:

❌ Incorrect - Loses reactivity:

const { data, isLoading } = useLiveQuery(...)

const { data, isLoading } = useLiveQuery(...)

✅ Correct - Maintains reactivity:

// Option 1: Use dot notation (recommended)
const query = useLiveQuery(...)
// Access: query.data, query.isLoading

// Option 2: Wrap with $derived for destructuring
const query = useLiveQuery(...)
const { data, isLoading } = $derived(query)

// Option 1: Use dot notation (recommended)
const query = useLiveQuery(...)
// Access: query.data, query.isLoading

// Option 2: Wrap with $derived for destructuring
const query = useLiveQuery(...)
const { data, isLoading } = $derived(query)

This is a fundamental Svelte 5 limitation, not a library bug. See: https://github.com/sveltejs/svelte/issues/11002

Examples

// Basic query with object syntax (recommended pattern)
const todosQuery = useLiveQuery((q) =>
  q.from({ todos: todosCollection })
   .where(({ todos }) => eq(todos.completed, false))
   .select(({ todos }) => ({ id: todos.id, text: todos.text }))
)
// Access via: todosQuery.data, todosQuery.isLoading, etc.

// Basic query with object syntax (recommended pattern)
const todosQuery = useLiveQuery((q) =>
  q.from({ todos: todosCollection })
   .where(({ todos }) => eq(todos.completed, false))
   .select(({ todos }) => ({ id: todos.id, text: todos.text }))
)
// Access via: todosQuery.data, todosQuery.isLoading, etc.

// With reactive dependencies
let minPriority = $state(5)
const todosQuery = useLiveQuery(
  (q) => q.from({ todos: todosCollection })
         .where(({ todos }) => gt(todos.priority, minPriority)),
  [() => minPriority] // Re-run when minPriority changes
)

// With reactive dependencies
let minPriority = $state(5)
const todosQuery = useLiveQuery(
  (q) => q.from({ todos: todosCollection })
         .where(({ todos }) => gt(todos.priority, minPriority)),
  [() => minPriority] // Re-run when minPriority changes
)

// Destructuring with $derived (if needed)
const query = useLiveQuery((q) =>
  q.from({ todos: todosCollection })
)
const { data, isLoading, isError } = $derived(query)
// Now data, isLoading, and isError maintain reactivity

// Destructuring with $derived (if needed)
const query = useLiveQuery((q) =>
  q.from({ todos: todosCollection })
)
const { data, isLoading, isError } = $derived(query)
// Now data, isLoading, and isError maintain reactivity

// Join pattern
const issuesQuery = useLiveQuery((q) =>
  q.from({ issues: issueCollection })
   .join({ persons: personCollection }, ({ issues, persons }) =>
     eq(issues.userId, persons.id)
   )
   .select(({ issues, persons }) => ({
     id: issues.id,
     title: issues.title,
     userName: persons.name
   }))
)

// Join pattern
const issuesQuery = useLiveQuery((q) =>
  q.from({ issues: issueCollection })
   .join({ persons: personCollection }, ({ issues, persons }) =>
     eq(issues.userId, persons.id)
   )
   .select(({ issues, persons }) => ({
     id: issues.id,
     title: issues.title,
     userName: persons.name
   }))
)

// Handle loading and error states in template
const todosQuery = useLiveQuery((q) =>
  q.from({ todos: todoCollection })
)

// In template:
// {#if todosQuery.isLoading}
//   <div>Loading...</div>
// {:else if todosQuery.isError}
//   <div>Error: {todosQuery.status}</div>
// {:else}
//   <ul>
//     {#each todosQuery.data as todo (todo.id)}
//       <li>{todo.text}</li>
//     {/each}
//   </ul>
// {/if}

// Handle loading and error states in template
const todosQuery = useLiveQuery((q) =>
  q.from({ todos: todoCollection })
)

// In template:
// {#if todosQuery.isLoading}
//   <div>Loading...</div>
// {:else if todosQuery.isError}
//   <div>Error: {todosQuery.status}</div>
// {:else}
//   <ul>
//     {#each todosQuery.data as todo (todo.id)}
//       <li>{todo.text}</li>
//     {/each}
//   </ul>
// {/if}

Call Signature

function useLiveQuery<TContext>(config, deps?): UseLiveQueryReturn<{ [K in string | number | symbol]: (TContext["result"] extends object ? any[any] : TContext["hasJoins"] extends true ? TContext["schema"] : TContext["schema"][TContext["fromSourceName"]])[K] }>;

function useLiveQuery<TContext>(config, deps?): UseLiveQueryReturn<{ [K in string | number | symbol]: (TContext["result"] extends object ? any[any] : TContext["hasJoins"] extends true ? TContext["schema"] : TContext["schema"][TContext["fromSourceName"]])[K] }>;

Defined in: useLiveQuery.svelte.ts:206

Create a live query using configuration object

Type Parameters

TContext

TContext extends Context

Parameters

config

LiveQueryCollectionConfig<TContext>

Configuration object with query and options

deps?

() => unknown[]

Array of reactive dependencies that trigger query re-execution when changed

Returns

Reactive object with query data, state, and status information

Examples

// Basic config object usage
const todosQuery = useLiveQuery({
  query: (q) => q.from({ todos: todosCollection }),
  gcTime: 60000
})

// Basic config object usage
const todosQuery = useLiveQuery({
  query: (q) => q.from({ todos: todosCollection }),
  gcTime: 60000
})

// With reactive dependencies
let filter = $state('active')
const todosQuery = useLiveQuery({
  query: (q) => q.from({ todos: todosCollection })
                 .where(({ todos }) => eq(todos.status, filter))
}, [() => filter])

// With reactive dependencies
let filter = $state('active')
const todosQuery = useLiveQuery({
  query: (q) => q.from({ todos: todosCollection })
                 .where(({ todos }) => eq(todos.status, filter))
}, [() => filter])

// Handle all states uniformly
const itemsQuery = useLiveQuery({
  query: (q) => q.from({ items: itemCollection })
})

// In template:
// {#if itemsQuery.isLoading}
//   <div>Loading...</div>
// {:else if itemsQuery.isError}
//   <div>Something went wrong</div>
// {:else if !itemsQuery.isReady}
//   <div>Preparing...</div>
// {:else}
//   <div>{itemsQuery.data.length} items loaded</div>
// {/if}

// Handle all states uniformly
const itemsQuery = useLiveQuery({
  query: (q) => q.from({ items: itemCollection })
})

// In template:
// {#if itemsQuery.isLoading}
//   <div>Loading...</div>
// {:else if itemsQuery.isError}
//   <div>Something went wrong</div>
// {:else if !itemsQuery.isReady}
//   <div>Preparing...</div>
// {:else}
//   <div>{itemsQuery.data.length} items loaded</div>
// {/if}

Call Signature

function useLiveQuery<TResult, TKey, TUtils>(liveQueryCollection): UseLiveQueryReturnWithCollection<TResult, TKey, TUtils>;

function useLiveQuery<TResult, TKey, TUtils>(liveQueryCollection): UseLiveQueryReturnWithCollection<TResult, TKey, TUtils>;

Defined in: useLiveQuery.svelte.ts:255

Subscribe to an existing query collection (can be reactive)

Type Parameters

TResult

TResult extends object

TKey

TKey extends string | number

TUtils

TUtils extends Record<string, any>

Parameters

liveQueryCollection

MaybeGetter<Collection<TResult, TKey, TUtils, StandardSchemaV1<unknown, unknown>, TResult>>

Pre-created query collection to subscribe to (can be a getter)

Returns

UseLiveQueryReturnWithCollection<TResult, TKey, TUtils>

Reactive object with query data, state, and status information

Examples

// Using pre-created query collection
const myLiveQuery = createLiveQueryCollection((q) =>
  q.from({ todos: todosCollection }).where(({ todos }) => eq(todos.active, true))
)
const queryResult = useLiveQuery(myLiveQuery)

// Using pre-created query collection
const myLiveQuery = createLiveQueryCollection((q) =>
  q.from({ todos: todosCollection }).where(({ todos }) => eq(todos.active, true))
)
const queryResult = useLiveQuery(myLiveQuery)

// Reactive query collection reference
let selectedQuery = $state(todosQuery)
const queryResult = useLiveQuery(() => selectedQuery)

// Switch queries reactively
selectedQuery = archiveQuery

// Reactive query collection reference
let selectedQuery = $state(todosQuery)
const queryResult = useLiveQuery(() => selectedQuery)

// Switch queries reactively
selectedQuery = archiveQuery

// Access query collection methods directly
const queryResult = useLiveQuery(existingQuery)

// Use underlying collection for mutations
const handleToggle = (id) => {
  queryResult.collection.update(id, draft => { draft.completed = !draft.completed })
}

// Access query collection methods directly
const queryResult = useLiveQuery(existingQuery)

// Use underlying collection for mutations
const handleToggle = (id) => {
  queryResult.collection.update(id, draft => { draft.completed = !draft.completed })
}

// Handle states consistently
const queryResult = useLiveQuery(sharedQuery)

// In template:
// {#if queryResult.isLoading}
//   <div>Loading...</div>
// {:else if queryResult.isError}
//   <div>Error loading data</div>
// {:else}
//   {#each queryResult.data as item (item.id)}
//     <Item {...item} />
//   {/each}
// {/if}

// Handle states consistently
const queryResult = useLiveQuery(sharedQuery)

// In template:
// {#if queryResult.isLoading}
//   <div>Loading...</div>
// {:else if queryResult.isError}
//   <div>Error loading data</div>
// {:else}
//   {#each queryResult.data as item (item.id)}
//     <Item {...item} />
//   {/each}
// {/if}