kysely-codegen generates Kysely type definitions from your database. That's it.
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
npm install @libsql/kysely-libsql
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
# LibSQL
DATABASE_URL=libsql://token@host:port/database
If your URL contains a password with special characters, those characters may need to be percent-encoded.
If you are using PlanetScale, make sure your URL contains this SSL query string parameter:
ssl={"rejectUnauthorized":true}
Then run:
kysely-codegen
This command will generate a .d.ts file from your database, for example:
import { ColumnType } from 'kysely';
export type Generated<T> = T extends ColumnType<infer S, infer I, infer U>
? ColumnType<S, I | undefined, U>
: ColumnType<T, T | undefined, T>;
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.
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; ... }[]
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