DataTypeMap

Maps PostgreSQL type OIDs to the DataType descriptor (encoder/decoder pair) used to convert values between JS and the wire format. It is also used in the other direction, to guess which OID a plain JS value (not wrapped in a BindParam) should be sent as.

Most code never needs to touch this directly: every query is encoded/decoded using GlobalTypeMap unless a per-call typeMap option overrides it. Create your own instance (optionally seeded from an existing one) to register additional or custom data types without affecting the rest of the application.

Constructor

new DataTypeMap(other?: DataTypeMap)

Argument	Type	Default	Description
other	DataTypeMap		An existing map to copy registered types from

import { DataTypeMap, GlobalTypeMap } from 'postgrejs';

const myTypeMap = new DataTypeMap(GlobalTypeMap);
myTypeMap.register(myCustomType);

const result = await connection.query('select * from my_table', {
  typeMap: myTypeMap,
});

Methods

get()

Returns the registered DataType for the given OID.

get(oid: OID): DataType

Argument	Type	Default	Description
oid	OID		PostgreSQL type OID

• Returns DataType

register()

Registers one or more data types, keyed by their oid. Registering with an OID that is already registered replaces the existing entry.

register(dataTypes: DataType | DataType[]): void

Argument	Type	Default	Description
dataTypes	DataType | DataType[]		One or more data type descriptors

determine()

Guesses the PostgreSQL type OID for a plain JS value, by checking registered types (most-recently-registered first) until one claims the value via its isType() predicate. Used for query parameters that are not wrapped in a BindParam, except a plain string, a Date, or an array of numbers/bigints/strings/Dates, which both the parameter path and stringifyValueForSQL()'s literal path send unspecified (as text) without asking determine() at all; see Strings, Dates, and numeric arrays go out unspecified. determine(value) called directly is unaffected by any of this and still answers varchar/timestamp/_int4 for those same values (GlobalTypeMap.determine([1, 2]) is still DataTypeOIDs._int4), since the bypass lives in the two call sites, not in determine() itself.

determine(value: any): OID

Argument	Type	Default	Description
value	any		Value to determine a type for

• Returns an OID, or DataTypeOIDs.unknown if value is null/undefined or no registered type matches

GlobalTypeMap

export const GlobalTypeMap: DataTypeMap;

A pre-populated singleton DataTypeMap instance, registered with every built-in data type (bool, int2/int4/int8, float4/float8, numeric, text/varchar/bpchar/name, uuid, json/jsonb, bytea, date/time/timestamp/timestamptz, geometric types, and their array counterparts). This is the type map used by Connection, Pool and PreparedStatement whenever a query does not supply its own typeMap option.