SpacetimeDB TypeScript SDK Reference

Module Structure

Tables are built with table(), bound with schema(), and exported as default. Reducers and lifecycle hooks are export const:

import { schema, table, t } from 'spacetimedb/server';

const score_record = table(
  { name: 'score_record', public: true },
  {
    id: t.u64().primaryKey().autoInc(),
    owner: t.identity(),
    value: t.u32(),
  }
);

const spacetimedb = schema({ score_record });  // ONE object, not spread args
export default spacetimedb;

export const addRecord = spacetimedb.reducer(
  { value: t.u32() },
  (ctx, { value }) => {
    ctx.db.score_record.insert({ id: 0n, owner: ctx.sender, value });
  }
);

Only table definitions belong in schema({...}). Row and object builders used as reducer arguments or view return types are not schema entries.

Named runtime exports are reserved for values registered with SpacetimeDB, such as reducers, lifecycle hooks, views, procedures, HTTP exports, and visibility filters. Keep ordinary helper functions and constants unexported.

Imports

Schema builders and module exports come from spacetimedb/server. Runtime value classes such as ScheduleAt, Timestamp, and ConnectionId come from the root spacetimedb package; Range comes from spacetimedb/server:

import {
  schema, table, t, SenderError,
  type InferSchema, type ReducerCtx,
} from 'spacetimedb/server';
import { ConnectionId, ScheduleAt, Timestamp } from 'spacetimedb';
import { Range } from 'spacetimedb/server';

Tables

table(OPTIONS, COLUMNS) takes two arguments. The name field MUST be snake_case:

const entity = table(
  { name: 'entity', public: true },
  {
    identity: t.identity().primaryKey(),
    name: t.string(),
    active: t.bool(),
  }
);

Options: name (snake_case, recommended), public: true, event: true, scheduled: (): any => reducerRef, indexes: [...]

ctx.db accessors are the keys passed to schema({...}), verbatim: schema({ score_record }) → ctx.db.score_record. Use snake_case keys matching the table name. Client codegen converts case; server ctx.db does not.

Column Types

Every column is a t builder value:

Modifiers: .primaryKey(), .autoInc(), .unique(), .index('btree'), .default(value).

Use .default(value) only for a newly appended migration-safe field. Do not put defaults on primary-key, unique, or auto-increment columns.

Optional columns: nickname: t.option(t.string())

Schema builders describe the database's wire types; they are not TypeScript type names. For example, a t.u16() value is a TypeScript number, not a value cast to a type named u16.

Indexes

Use inline .index('btree') when a single-column index does not need a named accessor. Use an indexes entry when the accessor is named explicitly or the index spans multiple columns. Every indexes entry requires columns; do not also add .index('btree') to the same column.

// Inline (preferred for single-column):
authorId: t.u64().index('btree'),
// Access: ctx.db.post.authorId.filter(authorId);

// Multi-column (named):
indexes: [{ accessor: 'by_group_user', algorithm: 'btree', columns: ['groupId', 'userId'] }]
// Access: ctx.db.membership.by_group_user.filter([groupId, userId]);

Prefer a multi-column index over filtering by one column and looping. Filter takes an array in index column order; a prefix scan passes the leading value bare: filter(groupId).

The published module's entry file must export the schema as default. If you split tables (schema.ts) from reducers/lifecycle (index.ts), re-export it from the entry:

// index.ts
export { default } from './schema';   // re-export the schema for the module entry

Reducers

Reducers are created with spacetimedb.reducer(...); the export name becomes the reducer name:

export const createEntity = spacetimedb.reducer(
  { name: t.string(), age: t.i32() },
  (ctx, { name, age }) => {
    ctx.db.entity.insert({ identity: ctx.sender, name, age, active: true });
  }
);

// No arguments, just the callback:
export const doReset = spacetimedb.reducer((ctx) => { ... });

Reducer args accept any column type, including arrays of custom types: { splits: t.array(Split) }. Do not pass JSON strings for structured data.

DB Operations

ctx.db.score_record.insert({ id: 0n, owner: ctx.sender, value: 1 });  // Insert (0n for autoInc)
ctx.db.score_record.id.find(recordId);                     // Find by PK → row | null
ctx.db.entity.identity.find(ctx.sender);                   // Find by unique column
[...ctx.db.post.authorId.filter(authorId)];                // Filter → spread to Array
[...ctx.db.entity.iter()];                                 // All rows → Array
ctx.db.score_record.id.update({ ...existing, value: 2 });  // Update (spread + override)
ctx.db.score_record.id.delete(recordId);                   // Delete by PK

Insert through the table accessor (ctx.db.score_record.insert(...)). Primary-key, unique, and index accessors support lookup or mutation of existing rows, but do not have insert(...).

insert(...) returns the inserted row, including database-assigned auto-increment fields.

The accessor for a primary key or index is the declared column name. For example, a primary key named eventId is accessed as ctx.db.event.eventId, not ctx.db.event.id.

The schema value registers module exports but does not expose database rows. Pass a context into any helper that needs ctx.db.

Note: iter() and filter() return iterators. Spread to Array for .sort(), .filter(), .map().

Lifecycle Hooks

MUST be export const. Bare calls are silently ignored:

export const init = spacetimedb.init((ctx) => { ... });
export const onConnect = spacetimedb.clientConnected((ctx) => { ... });
export const onDisconnect = spacetimedb.clientDisconnected((ctx) => { ... });

ctx.connectionId is ConnectionId | null, including in lifecycle contexts. Guard it before passing it to a helper or using it as a table key.

Reducer Context API

ctx is the only source of sender identity, time, and randomness; stdlib clocks and RNG are unavailable in modules. Let exported callbacks infer their context type. In helpers, use ReducerCtx<InferSchema<typeof spacetimedb>>; do not annotate a context as any, because that erases table row types and can make bigint expressions infer as number.

type Ctx = ReducerCtx<InferSchema<typeof spacetimedb>>;

function findRecord(ctx: Ctx, id: bigint) {
  return ctx.db.score_record.id.find(id);
}

// Auth: ctx.sender is the caller's Identity
if (!row.owner.equals(ctx.sender)) throw new SenderError('unauthorized');

// ctx.connectionId: the per-connection id, NULLABLE (ConnectionId | null) — null-check before use.
// One Identity can hold several connections (multiple tabs/devices).
if (ctx.connectionId) { /* ... */ }

// Server timestamp (deterministic per reducer call)
ctx.db.item.insert({ id: 0n, createdAt: ctx.timestamp });

// Deterministic RNG
const f: number = ctx.random();                          // [0.0, 1.0)
const roll: number = ctx.random.integerInRange(1, 6);    // safe JS number bounds/result, inclusive
const storedRoll: bigint = BigInt(roll);                 // convert the result for an i64/u64 column
const bytes: Uint8Array = ctx.random.fill(new Uint8Array(16));

// Client: Timestamp → Date
new Date(Number(row.createdAt.microsSinceUnixEpoch / 1000n));

Do not construct Identity values from strings (e.g. 'hex' as Identity): serialization fails and kills the module. Identities come from ctx.sender or t.identity() columns.

Construct a ConnectionId from its numeric representation with new ConnectionId(value) after importing ConnectionId from spacetimedb.

Construct exact timestamps with new Timestamp(micros) after importing Timestamp from spacetimedb. Inclusive index ranges use Range from spacetimedb/server:

import { Timestamp } from 'spacetimedb';
import { Range } from 'spacetimedb/server';

ctx.db.shipment.deliverBy.filter(new Range(
  { tag: 'included', value: new Timestamp(1_000n) },
  { tag: 'included', value: new Timestamp(2_000n) },
));

Scheduled Tables

The reducer or procedure referenced by a table's scheduled option must be exported.

import { ScheduleAt } from 'spacetimedb';   // ScheduleAt comes from the root package

const tick_timer = table({
  name: 'tick_timer',
  scheduled: (): any => tick,   // (): any => breaks circular dep
}, {
  scheduled_id: t.u64().primaryKey().autoInc(),
  scheduled_at: t.scheduleAt(),
});

export const tick = spacetimedb.reducer(
  { timer: tick_timer.rowType },
  (ctx, { timer }) => { /* timer row auto-deleted after this runs */ }
);

// One-time: ScheduleAt.time(ctx.timestamp.microsSinceUnixEpoch + delayMicros)
// Repeating: ScheduleAt.interval(60_000_000n)
// Read time back from a scheduleAt value (tagged union):
//   const micros = at.tag === 'time' ? at.value : at.value.microsSinceUnixEpoch;  // bigint

Custom Types

// Product type (struct):
const Position = t.object('Position', { x: t.i32(), y: t.i32() });
const entity = table({ name: 'entity' }, {
  id: t.u64().primaryKey().autoInc(),
  pos: Position,
});

// Sum type (tagged union):
const Shape = t.enum('Shape', {
  circle: t.i32(),
  rectangle: t.object('Rect', { w: t.i32(), h: t.i32() }),
});
// Values: { tag: 'circle', value: 10 }

Views

A client subscribing to a view receives only the rows it returns. Use a per-user view (keyed on ctx.sender) for per-viewer access control: deleting a row it depends on (e.g. a membership row) automatically drops the rows it was exposing from that client.

t.row(...) and t.object(...) return schema builders, not TypeScript runtime row types. Let a view callback infer its result, or annotate a separately declared structural type such as Array<{ sku: bigint; label: string }>. A named output type must not reuse the generated PascalCase name of its view accessor (for example, reserve DiscountedProduct for a discounted_product view).

Both spacetimedb.view(...) and spacetimedb.anonymousView(...) take three arguments: view options, the declared return schema, and the callback.

// Anonymous view (same for all clients):
export const activeUsers = spacetimedb.anonymousView(
  { name: 'active_users', public: true },
  t.array(entity.rowType),
  (ctx) => [...ctx.db.entity.iter()].filter(e => e.active)
);

// Per-user view (varies by ctx.sender):
export const myProfile = spacetimedb.view(
  { name: 'my_profile', public: true },
  t.option(entity.rowType),
  (ctx) => ctx.db.entity.identity.find(ctx.sender) ?? undefined
);

For a procedural view primary key, define the output with t.row and mark its field .primaryKey():

const CatalogKey = t.row('CatalogKey', {
  sku: t.u64().primaryKey(),
  label: t.string(),
});

Query-builder views use ctx.from and return the query directly. Because a query returns a row set, declare its return schema as t.array(tableName.rowType). Use where for predicates and rightSemijoin when the result should contain right-side rows that have a matching left-side row:

ctx => ctx.from.article.where(article => article.published.eq(true))
ctx => ctx.from.subscription.rightSemijoin(
  ctx.from.account,
  (subscription, account) => subscription.accountId.eq(account.id)
)

The method name identifies which side is returned: A.leftSemijoin(B, ...) returns rows from A, while A.rightSemijoin(B, ...) returns rows from B. To return one table's rows when another table has a match, put the returned table on the corresponding side. Semijoins do not project combined columns from both tables.

Procedural views read through ctx.db and return materialized values such as arrays. Query-builder values from ctx.from are returned directly; they are not iterators and cannot be spread, looped over, or mixed with array methods. Use a procedural view when the result is a custom row assembled from multiple tables.

Client Visibility Filters

export const privateNoteFilter = spacetimedb.clientVisibilityFilter.sql(
  'SELECT * FROM owned_row WHERE owner = :sender'
);

Procedures and HTTP

spacetimedb is the local schema value returned by schema({...}); it is not a named export to import from spacetimedb/server.

Procedures declare argument and return types:

const Result = t.object('Result', { value: t.string() });

export const inspect = spacetimedb.procedure(
  { input: t.string() },
  Result,
  (_ctx, { input }) => ({ value: input })
);

Procedure callbacks are synchronous. Do not mark them async or use await; return the declared value directly. A procedure with return type t.unit() returns {}.

TypeScript outbound HTTP uses ctx.http.fetch(url, options), including for non-GET requests; it does not provide convenience methods such as get() or post(). Responses expose the numeric status, headers.get(name), and text() APIs.

t.array(t.u8()) values are number[]. Convert one to new Uint8Array(value) before using it as a binary request body.

Procedures and handlers open short database transactions with ctx.withTx(tx => ...). Perform network I/O before opening the transaction; only database work belongs inside its callback.

Scheduled procedures use the ordinary scheduled-table shape. Its scheduled option references an exported spacetimedb.procedure(...) value instead of a reducer, and the procedure accepts the scheduled row as its argument.

Inbound HTTP uses httpHandler, httpRouter, Router, and SyncResponse:

httpHandler and httpRouter are methods on the local spacetimedb schema value, not named imports.

import { Router, SyncResponse } from 'spacetimedb/server';

export const health = spacetimedb.httpHandler((_ctx, _request) =>
  new SyncResponse('ok', {
    status: 200,
    headers: { 'content-type': 'text/plain' },
  })
);
export const routes = spacetimedb.httpRouter(new Router().get('/health', health));

Handlers are synchronous: return SyncResponse directly rather than marking the callback async. Pass the exported httpHandler(...) value to the router, not its raw callback. The router selects the path, while a handler reads request data with APIs such as request.text(); Request has no path property. A handler context does not expose ctx.db; use ctx.withTx(tx => ...) when a handler needs transactional database access.