CollectionImpl | TanStack DB Deutsch

Defined in: packages/db/src/collection/index.ts:380

Extended by

Collection

Type Parameters

TOutput

TOutput extends object = Record<string, unknown>

TKey

TKey extends string | number = string | number

TUtils

TUtils extends UtilsRecord = { }

TSchema

TSchema extends StandardSchemaV1 = StandardSchemaV1

TInput

TInput extends object = TOutput

Constructors

Constructor

new CollectionImpl<TOutput, TKey, TUtils, TSchema, TInput>(config): CollectionImpl<TOutput, TKey, TUtils, TSchema, TInput>;

Defined in: packages/db/src/collection/index.ts:426

Creates a new Collection instance

Parameters

config

CollectionImplConfig<TOutput, TKey, TUtils, TSchema>

Configuration object for the collection

Returns

CollectionImpl<TOutput, TKey, TUtils, TSchema, TInput>

Throws

Error if sync config is missing

Properties

_lifecycle

_lifecycle: CollectionLifecycleManager<TOutput, TKey, TSchema, TInput>;

Defined in: packages/db/src/collection/index.ts:397

_state

_state: CollectionStateManager<TOutput, TKey, TSchema, TInput>;

Defined in: packages/db/src/collection/index.ts:409

_sync

_sync: CollectionSyncManager<TOutput, TKey, TSchema, TInput>;

Defined in: packages/db/src/collection/index.ts:398

config

config: CollectionConfig<TOutput, TKey, TSchema, TUtils>;

Defined in: packages/db/src/collection/index.ts:388

deferDataRefresh

deferDataRefresh: Promise<void> | null = null;

Defined in: packages/db/src/collection/index.ts:416

When set, collection consumers should defer processing incoming data refreshes until this promise resolves. This prevents stale data from overwriting optimistic state while pending writes are being applied.

id

id: string;

Defined in: packages/db/src/collection/index.ts:387

utils

utils: TUtils;

Defined in: packages/db/src/collection/index.ts:392

Accessors

_layoutRevision

Get Signature

get _layoutRevision(): number;

Defined in: packages/db/src/collection/index.ts:564

Monotonic revision of explicit layout-only publications. Internal — used to distinguish them from empty ready events.

Returns

number

_stateRevision

Get Signature

get _stateRevision(): number;

Defined in: packages/db/src/collection/index.ts:556

Monotonic revision of the collection's visible state; advances once per committed batch of changes and cleanup, even while nothing is subscribed. Internal — used by the live-query observer's snapshot cache.

Returns

number

base

Get Signature

get base(): CollectionBase<TKey, TOutput>;

Defined in: packages/db/src/collection/index.ts:704

The exposed authoritative base rows, before optimistic writes are applied. Queued sync writes are excluded. Reading does not start sync. Do not mutate the backing map or its rows: that bypasses publication.

Returns

CollectionBase<TKey, TOutput>

compareOptions

Get Signature

get compareOptions(): StringCollationConfig;

Defined in: packages/db/src/collection/index.ts:884

Returns

StringCollationConfig

indexes

Get Signature

get indexes(): Map<number, BaseIndex<TKey>>;

Defined in: packages/db/src/collection/index.ts:869

Get resolved indexes for query optimization

Returns

Map<number, BaseIndex<TKey>>

isLoadingSubset

Get Signature

get isLoadingSubset(): boolean;

Defined in: packages/db/src/collection/index.ts:622

Check if the collection is currently loading more data

Returns

boolean

true if the collection has pending load more operations, false otherwise

size

Get Signature

get size(): number;

Defined in: packages/db/src/collection/index.ts:734

Get the current size of the collection (cached)

Returns

number

state

Get Signature

get state(): Map<TKey, WithVirtualProps<TOutput, TKey>>;

Defined in: packages/db/src/collection/index.ts:1061

Gets the current state of the collection as a Map

Example

const itemsMap = collection.state
console.log(`Collection has ${itemsMap.size} items`)

for (const [key, item] of itemsMap) {
  console.log(`${key}: ${item.title}`)
}

// Check if specific item exists
if (itemsMap.has("todo-1")) {
  console.log("Todo 1 exists:", itemsMap.get("todo-1"))
}

Returns

Map<TKey, WithVirtualProps<TOutput, TKey>>

Map containing all items in the collection, with keys as identifiers

status

Get Signature

get status(): CollectionStatus;

Defined in: packages/db/src/collection/index.ts:539

Gets the current status of the collection

Returns

CollectionStatus

subscriberCount

Get Signature

get subscriberCount(): number;

Defined in: packages/db/src/collection/index.ts:547

Get the number of subscribers that ask for this collection's data. A live query that has no subscriber or preload of its own does not count.

Returns

number

toArray

Get Signature

get toArray(): WithVirtualProps<TOutput, TKey>[];

Defined in: packages/db/src/collection/index.ts:1091

Gets the current state of the collection as an Array

Returns

WithVirtualProps<TOutput, TKey>[]

An Array containing all items in the collection

Methods

_deferPublication()

_deferPublication(): PublicationDeferral;

Defined in: packages/db/src/collection/index.ts:579

Defer subscriber events until a coherent multi-Collection commit ends.

Returns

PublicationDeferral

_deferSyncStart()

_deferSyncStart(): boolean;

Defined in: packages/db/src/collection/index.ts:651

Internal

Returns

boolean

_hasHydratedKey()

_hasHydratedKey(key): boolean;

Defined in: packages/db/src/collection/index.ts:646

Internal

Parameters

key

TKey

Returns

boolean

_hasSubscriberOrPreload()

_hasSubscriberOrPreload(): boolean;

Defined in: packages/db/src/collection/index.ts:690

Internal

Whether this Collection had a subscriber or a preload in this sync run.

Returns

boolean

_markLayoutChange()

_markLayoutChange(): void;

Defined in: packages/db/src/collection/index.ts:574

Mark the active sync transaction as layout-changing. Internal.

Returns

void

_markPreload()

_markPreload(): void;

Defined in: packages/db/src/collection/index.ts:685

Internal

Record a preload without starting one, for a caller whose data request another promise answers, such as a DbClient stream for the same query. The request still counts: deferred acquisition may now resume.

Returns

void

_onCleanupStart()

_onCleanupStart(callback): () => void;

Defined in: packages/db/src/collection/index.ts:636

Internal

Subscribe to the synchronous cleanup-start boundary.

Parameters

callback

() => void

Returns

(): void;

Returns

void

_onFirstSubscriberOrPreload()

_onFirstSubscriberOrPreload(listener): () => void;

Defined in: packages/db/src/collection/index.ts:695

Internal

Listen for the first subscriber or preload in this sync run.

Parameters

listener

() => void

Returns

(): void;

Returns

void

_resumeSyncStart()

_resumeSyncStart(): void;

Defined in: packages/db/src/collection/index.ts:656

Internal

Returns

void

_setTransactionScope()

_setTransactionScope(transactionScope): void;

Defined in: packages/db/src/collection/index.ts:641

Internal

Parameters

transactionScope

TransactionScope

Returns

void

_subscribeLayoutChanges()

_subscribeLayoutChanges(listener): () => void;

Defined in: packages/db/src/collection/index.ts:569

Subscribe to layout-only publications. Internal observer channel.

Parameters

listener

() => void

Returns

(): void;

Returns

void

_syncedRowMetadataKeysOutsideBase()

_syncedRowMetadataKeysOutsideBase(): TKey[];

Defined in: packages/db/src/collection/index.ts:709

Internal

Applied metadata keys without a source row.

Returns

TKey[]

[iterator]()

iterator: IterableIterator<[TKey, WithVirtualProps<TOutput, TKey>]>;

Defined in: packages/db/src/collection/index.ts:772

Get all entries (virtual derived state)

Returns

IterableIterator<[TKey, WithVirtualProps<TOutput, TKey>]>

cleanup()

cleanup(): Promise<void>;

Defined in: packages/db/src/collection/index.ts:1264

Clean up the collection by stopping sync and clearing data This can be called manually or automatically by garbage collection Cleanup callbacks must not restart this collection or call its preload(). Wait until cleanup completes before starting a new sync run. If adapter cleanup rejects, this promise rejects after the Collection reaches its final cleaned-up state.

Returns

Promise<void>

createIndex()

createIndex<TIndexType>(indexCallback, config): BaseIndex<TKey>;

Defined in: packages/db/src/collection/index.ts:838

Creates an index on a collection for faster queries. Indexes significantly improve query performance by allowing constant time lookups and logarithmic time range queries instead of full scans.

Type Parameters

TIndexType

TIndexType extends IndexConstructor<TKey>

Parameters

indexCallback

(row) => any

Function that extracts the indexed value from each item

config

IndexOptions<TIndexType> = {}

Configuration including index type and type-specific options

Returns

BaseIndex<TKey>

The created index

Example

import { BasicIndex } from '@tanstack/db'

// Create an index with explicit type
const ageIndex = collection.createIndex((row) => row.age, {
  indexType: BasicIndex
})

// Create an index with collection's default type
const nameIndex = collection.createIndex((row) => row.name)

currentStateAsChanges()

currentStateAsChanges(options): 
  | void
  | ChangeMessage<WithVirtualProps<TOutput, TKey>, TKey>[];

Defined in: packages/db/src/collection/index.ts:1130

Returns the current state of the collection as an array of changes

Parameters

options

CurrentStateAsChangesOptions = {}

Options including optional where filter

Returns

| void | ChangeMessage<WithVirtualProps<TOutput, TKey>, TKey>[]

An array of changes

Example

// Get all items as changes
const allChanges = collection.currentStateAsChanges()

// Get only items matching a condition
const activeChanges = collection.currentStateAsChanges({
  where: (row) => row.status === 'active'
})

// Get only items using a pre-compiled expression
const activeChanges = collection.currentStateAsChanges({
  whereExpression: eq(row.status, 'active')
})

delete()

delete(keys, config?): Transaction<any>;

Defined in: packages/db/src/collection/index.ts:1038

Deletes one or more items from the collection

Parameters

keys

Single key or array of keys to delete

TKey | TKey[]

config?

OperationConfig

Optional configuration including metadata

Returns

Transaction<any>

A Transaction object representing the delete operation(s)

Examples

// Delete a single item
const tx = collection.delete("todo-1")
await tx.when('settled')

// Delete multiple items
const tx = collection.delete(["todo-1", "todo-2"])
await tx.when('settled')

// Delete with metadata
const tx = collection.delete("todo-1", { metadata: { reason: "completed" } })
await tx.when('settled')

// Handle errors
try {
  const tx = collection.delete("item-1")
  await tx.when('settled')
  console.log('Delete successful')
} catch (error) {
  console.log('Delete failed:', error)
}

entries()

entries(): IterableIterator<[TKey, WithVirtualProps<TOutput, TKey>]>;

Defined in: packages/db/src/collection/index.ts:760

Get all entries (virtual derived state)

Returns

IterableIterator<[TKey, WithVirtualProps<TOutput, TKey>]>

forEach()

forEach(callbackfn): void;

Defined in: packages/db/src/collection/index.ts:781

Execute a callback for each entry in the collection

Parameters

callbackfn

(value, key, index) => void

Returns

void

get()

get(key): 
  | WithVirtualProps<TOutput, TKey>
  | undefined;

Defined in: packages/db/src/collection/index.ts:720

Get the current value for a key (virtual derived state)

Parameters

key

TKey

Returns

| WithVirtualProps<TOutput, TKey> | undefined

getIndexMetadata()

getIndexMetadata(): CollectionIndexMetadata[];

Defined in: packages/db/src/collection/index.ts:862

Returns a snapshot of current index metadata sorted by indexId. Persistence wrappers can use this to bootstrap index state if indexes were created before event listeners were attached.

Returns

CollectionIndexMetadata[]

getKeyFromItem()

getKeyFromItem(item): TKey;

Defined in: packages/db/src/collection/index.ts:812

Parameters

item

TOutput

Returns

TKey

has()

has(key): boolean;

Defined in: packages/db/src/collection/index.ts:727

Check if a key exists in the collection (virtual derived state)

Parameters

key

TKey

Returns

boolean

insert()

insert(data, config?): 
  | Transaction<Record<string, unknown>>
| Transaction<TOutput>;

Defined in: packages/db/src/collection/index.ts:925

Inserts one or more items into the collection

Parameters

data

TInput | TInput[]

config?

InsertConfig

Optional configuration including metadata

Returns

| Transaction<Record<string, unknown>> | Transaction<TOutput>

A Transaction object representing the insert operation(s)

Throws

If the data fails schema validation

Examples

// Insert a single todo (requires onInsert handler)
const tx = collection.insert({ id: "1", text: "Buy milk", completed: false })
await tx.when('settled')

// Insert multiple todos at once
const tx = collection.insert([
  { id: "1", text: "Buy milk", completed: false },
  { id: "2", text: "Walk dog", completed: true }
])
await tx.when('settled')

// Insert with metadata
const tx = collection.insert({ id: "1", text: "Buy groceries" },
  { metadata: { source: "mobile-app" } }
)
await tx.when('settled')

// Handle errors
try {
  const tx = collection.insert({ id: "1", text: "New item" })
  await tx.when('settled')
  console.log('Insert successful')
} catch (error) {
  console.log('Insert failed:', error)
}

isReady()

isReady(): boolean;

Defined in: packages/db/src/collection/index.ts:614

Check if the collection is ready for use Returns true if the collection has been marked as ready by its sync implementation

Returns

boolean

true if the collection is ready, false otherwise

Example

if (collection.isReady()) {
  console.log('Collection is ready, data is available')
  // Safe to access collection.state
} else {
  console.log('Collection is still loading')
}

keys()

keys(): IterableIterator<TKey>;

Defined in: packages/db/src/collection/index.ts:741

Get all keys (virtual derived state)

Returns

IterableIterator<TKey>

map()

map<U>(callbackfn): U[];

Defined in: packages/db/src/collection/index.ts:797

Create a new array with the results of calling a function for each entry in the collection

Type Parameters

U

U

Parameters

callbackfn

(value, key, index) => U

Returns

U[]

off()

off<T>(event, callback): void;

Defined in: packages/db/src/collection/index.ts:1239

Unsubscribe from a collection event

Type Parameters

T

Parameters

event

T

callback

CollectionEventHandler<T>

Returns

void

on()

on<T>(event, callback): () => void;

Defined in: packages/db/src/collection/index.ts:1219

Subscribe to a collection event

Type Parameters

T

Parameters

event

T

callback

CollectionEventHandler<T>

Returns

(): void;

Returns

void

once()

once<T>(event, callback): () => void;

Defined in: packages/db/src/collection/index.ts:1229

Subscribe to a collection event once

Type Parameters

T

Parameters

event

T

callback

CollectionEventHandler<T>

Returns

(): void;

Returns

void

onFirstReady()

onFirstReady(callback): () => void;

Defined in: packages/db/src/collection/index.ts:598

Register a callback to be executed when the collection first becomes ready Useful for preloading collections Every callback queued before the transition runs. Because ready state is established first, callbacks registered during or after delivery run immediately. If one throws, the collection remains ready. Direct sync startup rethrows the first failure; preload resolves from ready state. Cleanup discards pending callbacks without invoking them.

Parameters

callback

() => void

Function to call when the collection first becomes ready

Returns

(): void;

Returns

void

Example

collection.onFirstReady(() => {
  console.log('Collection is ready for the first time')
  // Safe to access collection.state now
})

preload()

preload(): Promise<void>;

Defined in: packages/db/src/collection/index.ts:664

Preload the collection data by starting sync if not already started Multiple concurrent calls will share the same promise

Returns

Promise<void>

removeIndex()

removeIndex(indexOrId): boolean;

Defined in: packages/db/src/collection/index.ts:853

Removes an index created with createIndex. Returns true when an index existed and was removed.

Best-effort semantics: removing an index guarantees it is detached from collection query planning. Existing index proxy references should be treated as invalid after removal.

Parameters

indexOrId

number | BaseIndex<TKey>

Returns

boolean

startSyncImmediate()

startSyncImmediate(): void;

Defined in: packages/db/src/collection/index.ts:631

Start sync immediately - internal method for compiled queries This bypasses lazy loading for special cases like live query results Throws during active cleanup; restart after cleanup completes instead.

Returns

void

stateWhenReady()

stateWhenReady(): Promise<Map<TKey, WithVirtualProps<TOutput, TKey>>>;

Defined in: packages/db/src/collection/index.ts:1075

Gets the current state of the collection as a Map, but only resolves when data is available Waits for the first sync commit to complete before resolving

Returns

Promise<Map<TKey, WithVirtualProps<TOutput, TKey>>>

Promise that resolves to a Map containing all items in the collection

subscribeChanges()

Call Signature

subscribeChanges(callback, options?): CollectionSubscription;

Defined in: packages/db/src/collection/index.ts:1182

Subscribe to changes in the collection Changes to the same key retain their causal order within a callback. Changes to different keys have no promised order within a callback.

Parameters

callback

(changes) => void

Function called when items change

options?

SubscribeChangesOptions<TOutput, TKey>

Subscription options including includeInitialState and where filter

Returns

CollectionSubscription

Unsubscribe function - Call this to stop listening for changes

Examples

// Basic subscription
const subscription = collection.subscribeChanges((changes) => {
  changes.forEach(change => {
    console.log(`${change.type}: ${change.key}`, change.value)
  })
})

// Later: subscription.unsubscribe()

// Include current state immediately
const subscription = collection.subscribeChanges((changes) => {
  updateUI(changes)
}, { includeInitialState: true })

// Subscribe only to changes matching a condition using where callback
import { eq } from "@tanstack/db"

const subscription = collection.subscribeChanges((changes) => {
  updateUI(changes)
}, {
  includeInitialState: true,
  where: (row) => eq(row.status, "active")
})

// Using multiple conditions with and()
import { and, eq, gt } from "@tanstack/db"

const subscription = collection.subscribeChanges((changes) => {
  updateUI(changes)
}, {
  where: (row) => and(eq(row.status, "active"), gt(row.priority, 5))
})

Call Signature

subscribeChanges(callback, options?): CollectionSubscription;

Defined in: packages/db/src/collection/index.ts:1190

Subscribe to changes in the collection Changes to the same key retain their causal order within a callback. Changes to different keys have no promised order within a callback.

Parameters

callback

Function called when items change

(changes) => void | (changes) => void

options?

SubscribeChangesOptions<TOutput, TKey>

Subscription options including includeInitialState and where filter

Returns

CollectionSubscription

Unsubscribe function - Call this to stop listening for changes

Examples

// Basic subscription
const subscription = collection.subscribeChanges((changes) => {
  changes.forEach(change => {
    console.log(`${change.type}: ${change.key}`, change.value)
  })
})

// Later: subscription.unsubscribe()

// Include current state immediately
const subscription = collection.subscribeChanges((changes) => {
  updateUI(changes)
}, { includeInitialState: true })

// Subscribe only to changes matching a condition using where callback
import { eq } from "@tanstack/db"

const subscription = collection.subscribeChanges((changes) => {
  updateUI(changes)
}, {
  includeInitialState: true,
  where: (row) => eq(row.status, "active")
})

// Using multiple conditions with and()
import { and, eq, gt } from "@tanstack/db"

const subscription = collection.subscribeChanges((changes) => {
  updateUI(changes)
}, {
  where: (row) => and(eq(row.status, "active"), gt(row.priority, 5))
})

toArrayWhenReady()

toArrayWhenReady(): Promise<WithVirtualProps<TOutput, TKey>[]>;

Defined in: packages/db/src/collection/index.ts:1101

Gets the current state of the collection as an Array, but only resolves when data is available Waits for the first sync commit to complete before resolving

Returns

Promise<WithVirtualProps<TOutput, TKey>[]>

Promise that resolves to an Array containing all items in the collection

update()

Call Signature

update(key, callback): Transaction;

Defined in: packages/db/src/collection/index.ts:970

Updates one or more items in the collection using a callback function

Parameters

key

TKey[]

callback

(drafts) => void

Returns

Transaction

A Transaction object representing the update operation(s)

Throws

If the updated data fails schema validation

Examples

// Update single item by key
const tx = collection.update("todo-1", (draft) => {
  draft.completed = true
})
await tx.when('settled')

// Update multiple items
const tx = collection.update(["todo-1", "todo-2"], (drafts) => {
  drafts.forEach(draft => { draft.completed = true })
})
await tx.when('settled')

// Update with metadata
const tx = collection.update("todo-1",
  { metadata: { reason: "user update" } },
  (draft) => { draft.text = "Updated text" }
)
await tx.when('settled')

// Handle errors
try {
  const tx = collection.update("item-1", draft => { draft.value = "new" })
  await tx.when('settled')
  console.log('Update successful')
} catch (error) {
  console.log('Update failed:', error)
}

Call Signature

update(
   keys, 
   config, 
   callback): Transaction;

Defined in: packages/db/src/collection/index.ts:976

Updates one or more items in the collection using a callback function

Parameters

keys

TKey[]

Single key or array of keys to update

config

OperationConfig

callback

(drafts) => void

Returns

Transaction

A Transaction object representing the update operation(s)

Throws

If the updated data fails schema validation

Examples

// Update single item by key
const tx = collection.update("todo-1", (draft) => {
  draft.completed = true
})
await tx.when('settled')

// Update multiple items
const tx = collection.update(["todo-1", "todo-2"], (drafts) => {
  drafts.forEach(draft => { draft.completed = true })
})
await tx.when('settled')

// Update with metadata
const tx = collection.update("todo-1",
  { metadata: { reason: "user update" } },
  (draft) => { draft.text = "Updated text" }
)
await tx.when('settled')

// Handle errors
try {
  const tx = collection.update("item-1", draft => { draft.value = "new" })
  await tx.when('settled')
  console.log('Update successful')
} catch (error) {
  console.log('Update failed:', error)
}

Call Signature

update(id, callback): Transaction;

Defined in: packages/db/src/collection/index.ts:983

Updates one or more items in the collection using a callback function

Parameters

id

TKey

callback

(draft) => void

Returns

Transaction

A Transaction object representing the update operation(s)

Throws

If the updated data fails schema validation

Examples

// Update single item by key
const tx = collection.update("todo-1", (draft) => {
  draft.completed = true
})
await tx.when('settled')

// Update multiple items
const tx = collection.update(["todo-1", "todo-2"], (drafts) => {
  drafts.forEach(draft => { draft.completed = true })
})
await tx.when('settled')

// Update with metadata
const tx = collection.update("todo-1",
  { metadata: { reason: "user update" } },
  (draft) => { draft.text = "Updated text" }
)
await tx.when('settled')

// Handle errors
try {
  const tx = collection.update("item-1", draft => { draft.value = "new" })
  await tx.when('settled')
  console.log('Update successful')
} catch (error) {
  console.log('Update failed:', error)
}

Call Signature

update(
   id, 
   config, 
   callback): Transaction;

Defined in: packages/db/src/collection/index.ts:989

Updates one or more items in the collection using a callback function

Parameters

id

TKey

config

OperationConfig

callback

(draft) => void

Returns

Transaction

A Transaction object representing the update operation(s)

Throws

If the updated data fails schema validation

Examples

// Update single item by key
const tx = collection.update("todo-1", (draft) => {
  draft.completed = true
})
await tx.when('settled')

// Update multiple items
const tx = collection.update(["todo-1", "todo-2"], (drafts) => {
  drafts.forEach(draft => { draft.completed = true })
})
await tx.when('settled')

// Update with metadata
const tx = collection.update("todo-1",
  { metadata: { reason: "user update" } },
  (draft) => { draft.text = "Updated text" }
)
await tx.when('settled')

// Handle errors
try {
  const tx = collection.update("item-1", draft => { draft.value = "new" })
  await tx.when('settled')
  console.log('Update successful')
} catch (error) {
  console.log('Update failed:', error)
}

validateData()

validateData(
   data, 
   type, 
   key?): TOutput;

Defined in: packages/db/src/collection/index.ts:876

Validates the data against the schema

Parameters

data

unknown

type

"insert" | "update"

key?

TKey

Returns

TOutput

values()

values(): IterableIterator<WithVirtualProps<TOutput, TKey>>;

Defined in: packages/db/src/collection/index.ts:748

Get all values (virtual derived state)

Returns

IterableIterator<WithVirtualProps<TOutput, TKey>>

waitFor()

waitFor<T>(event, timeout?): Promise<AllCollectionEvents[T]>;

Defined in: packages/db/src/collection/index.ts:1249

Wait for a collection event

Type Parameters

T

Parameters

event

T

timeout?

number

Returns

Promise<AllCollectionEvents[T]>