Type mapping

How pg-describe-gen turns a PostgreSQL type name into a TypeScript type.

PostgreSQL	TypeScript
`smallint`, `integer`, `real`, `double precision`	`number`
`bigint`	`string`	an int8 does not fit in a JS number; node-postgres returns a string
`numeric`, `decimal`	`string`	arbitrary precision, and floats are wrong for money
`boolean`	`boolean`
`text`, `varchar`, `char`, `uuid`, `citext`, `inet`, `interval`	`string`
`date`, `timestamp`, `timestamptz`	`Date`
`time`, `time with time zone`	`string`	no `Date` equivalent
`bytea`	`Buffer`
`json`, `jsonb`	`unknown`	narrow it yourself
`T[]`	`T[]`	any dimension
anything else	`unknown`	with a warning

The mapping targets what node-postgres actually returns at run time, not what the SQL type resembles. bigint and numeric arriving as strings is the case that surprises people, and typing them number would be a lie the compiler would then help you build on.

Overriding

Enums, domains and user-defined types fall through to unknown with a warning. Map them, or override any built-in, with a types block in the config:

{
  "queries": "queries",
  "output": "src/generated/queries.ts",
  "types": {
    "order_status": "'pending' | 'shipped' | 'cancelled'",
    "bigint": "bigint",
    "jsonb": "Record<string, unknown>"
  }
}

Keys are PostgreSQL type names as pg_describe reports them in type_name; the quickest way to get the exact spelling is to run the query and look:

SELECT DISTINCT type_name FROM pg_describe($$SELECT * FROM orders$$);

Values are emitted verbatim into the generated file, so any TypeScript type expression works — a union, an imported type name, a branded type. Nothing validates it beyond tsc on the generated output.

If you map bigint to the JS bigint, remember to configure node-postgres to parse int8 accordingly; the generator describes types, it does not install parsers.

Overriding​

Overriding