Kysely Codegen
kysely-codegen generates Kysely type definitions from your database. That's it.
Table of contents
Installation
npm install --save-dev kysely-codegen
# You will also need to install Kysely with your driver of choice:
npm install kysely pg
npm install kysely mysql2
npm install kysely better-sqlite3
Generating type definitions
The most convenient way to get started is to create an .env file with your database connection string:
# PostgreSQL
DATABASE_URL=postgres://username:[email protected]/database
# MySQL
DATABASE_URL=mysql://username:[email protected]/database
# SQLite
DATABASE_URL=C:/Program Files/sqlite3/db
If you're using PlanetScale, make sure the url contains an SSL query string parameter as follows:
ssl={"rejectUnauthorized":true}.
Then run:
kysely-codegen
This command will generate a .d.ts file from your database, for example:
import { Generated, ColumnType } from 'kysely';
export type Timestamp = ColumnType<Date, Date | string, Date | string>;
export interface Company {
id: Generated<number>;
name: string;
}
export interface User {
company_id: number | null;
created_at: Generated<Timestamp>;
email: string;
id: Generated<number>;
is_active: boolean;
name: string;
updated_at: Timestamp;
}
export interface DB {
company: Company;
user: User;
}For more options, run kysely-codegen --help.
Using the type definitions
Import DB into new Kysely<DB>, and you're done!
import { Kysely, PostgresDialect } from 'kysely';
import { DB } from 'kysely-codegen';
import { Pool } from 'pg';
const db = new Kysely<DB>({
dialect: new PostgresDialect({
pool: new Pool({
connectionString: process.env.DATABASE_URL,
}),
}),
});
const rows = await db.selectFrom('user').selectAll().execute();
// [
// {
// company_id: number | null;
// created_at: Date;
// email: string;
// id: number;
// is_active: boolean;
// name: string;
// updated_at: Date;
// }
// ]