Common way of defining custom types

Examples

The best way to see how customType definition is working is to check how existing data types in postgres and mysql could be defined using customType function from Drizzle ORM.

Postgres Data Types

MySql Data Types

Serial

import { customType } from 'drizzle-orm/pg-core';

const customSerial = customType<{ data: number; notNull: true; default: true }>(
  {
    dataType() {
      return 'serial';
    },
  },
);

Text

import { customType } from 'drizzle-orm/pg-core';

const customText = customType<{ data: string }>({
  dataType() {
    return 'text';
  },
});

Boolean

import { customType } from 'drizzle-orm/pg-core';

const customBoolean = customType<{ data: boolean }>({
  dataType() {
    return 'boolean';
  },
});

Jsonb

import { customType } from 'drizzle-orm/pg-core';

const customJsonb = <TData>(name: string) =>
  customType<{ data: TData; driverData: string }>({
    dataType() {
      return 'jsonb';
    },
    toDriver(value: TData): string {
      return JSON.stringify(value);
    },
  })(name);

Timestamp

import { customType } from 'drizzle-orm/pg-core';

const customTimestamp = customType<
  {
    data: Date;
    driverData: string;
    config: { withTimezone: boolean; precision?: number };
  }
>({
  dataType(config) {
    const precision = typeof config.precision !== 'undefined'
      ? ` (${config.precision})`
      : '';
    return `timestamp${precision}${
      config.withTimezone ? ' with time zone' : ''
    }`;
  },
  fromDriver(value: string): Date {
    return new Date(value);
  },
});

Usage for all types will be same as defined functions in Drizzle ORM. For example:

const usersTable = pgTable('users', {
  id: customSerial('id').primaryKey(),
  name: customText('name').notNull(),
  verified: customBoolean('verified').notNull().default(false),
  jsonb: customJsonb<string[]>('jsonb'),
  createdAt: customTimestamp('created_at', { withTimezone: true }).notNull()
    .default(sql`now()`),
});

Serial

import { customType } from 'drizzle-orm/mysql-core';

const customInt = customType<{ data: number; notNull: false; default: false }>(
  {
    dataType() {
      return 'int';
    },
  },
);

Text

import { customType } from 'drizzle-orm/mysql-core';

const customText = customType<{ data: string }>({
  dataType() {
    return 'text';
  },
});

Boolean

import { customType } from 'drizzle-orm/mysql-core';

const customBoolean = customType<{ data: boolean }>({
  dataType() {
    return 'boolean';
  },
  fromDriver(value) {
    if (typeof value === 'boolean') {
      return value;
    }
    return value === 1;
  },
});

Json

import { customType } from 'drizzle-orm/mysql-core';

const customJson = <TData>(name: string) =>
  customType<{ data: TData; driverData: string }>({
    dataType() {
      return 'json';
    },
    toDriver(value: TData): string {
      return JSON.stringify(value);
    },
  })(name);

Timestamp

import { customType } from 'drizzle-orm/mysql-core';

const customTimestamp = customType<
  { data: Date; driverData: string; config: { fsp: number } }
>({
  dataType(config) {
    const precision = typeof config.fsp !== 'undefined'
      ? ` (${config.fsp})`
      : '';
    return `timestamp${precision}`;
  },
  fromDriver(value: string): Date {
    return new Date(value);
  },
});

Usage for all types will be same as defined functions in Drizzle ORM. For example:

const usersTable = mysqlTable('userstest', {
  id: customInt('id').primaryKey(),
  name: customText('name').notNull(),
  verified: customBoolean('verified').notNull().default(false),
  jsonb: customJson<string[]>('jsonb'),
  createdAt: customTimestamp('created_at', { fsp: 2 }).notNull().default(
    sql`now()`,
  ),
});

TS-doc for type definitions

You can check ts-doc for types and param definition.

export type CustomTypeValues = {
  /**
   * Required type for custom column, that will infer proper type model
   *
   * Examples:
   *
   * If you want your column to be `string` type after selecting/or on inserting - use `data: string`. Like `text`, `varchar`
   *
   * If you want your column to be `number` type after selecting/or on inserting - use `data: number`. Like `integer`
   */
  data: unknown;

  /**
   * Type helper, that represents what type database driver is accepting for specific database data type
   */
  driverData?: unknown;

  /**
   * What config type should be used for {@link CustomTypeParams} `dataType` generation
   */
  config?: Record<string, unknown>;

  /**
   * If your custom data type should be notNull by default you can use `notNull: true`
   *
   * @example
   * const customSerial = customType<{ data: number, notNull: true, default: true }>({
   *    dataType() {
   *      return 'serial';
   *    },
   * });
   */
  notNull?: boolean;

  /**
   * If your custom data type has default you can use `default: true`
   *
   * @example
   * const customSerial = customType<{ data: number, notNull: true, default: true }>({
   *    dataType() {
   *      return 'serial';
   *    },
   * });
   */
  default?: boolean;
};

export interface CustomTypeParams<T extends CustomTypeValues> {
  /**
   * Database data type string representation, that is used for migrations
   * @example
   * ```
   * `jsonb`, `text`
   * ```
   *
   * If database data type needs additional params you can use them from `config` param
   * @example
   * ```
   * `varchar(256)`, `numeric(2,3)`
   * ```
   *
   * To make `config` be of specific type please use config generic in {@link CustomTypeValues}
   *
   * @example
   * Usage example
   * ```
   *   dataType() {
   *     return 'boolean';
   *   },
   * ```
   * Or
   * ```
   *   dataType(config) {
   *     return typeof config.length !== 'undefined' ? `varchar(${config.length})` : `varchar`;
   *   }
   * ```
   */
  dataType: (config: T['config']) => string;

  /**
   * Optional mapping function, between user input and driver
   * @example
   * For example, when using jsonb we need to map JS/TS object to string before writing to database
   * ```
   * toDriver(value: TData): string {
   *   return JSON.stringify(value);
   * }
   * ```
   */
  toDriver?: (value: T['data']) => T['driverData'];

  /**
   * Optional mapping function, that is responsible for data mapping from database to JS/TS code
   * @example
   * For example, when using timestamp we need to map string Date representation to JS Date
   * ```
   * fromDriver(value: string): Date {
   *  return new Date(value);
   * },
   * ```
   */
  fromDriver?: (value: T['driverData']) => T['data'];
}