Your TypeScript Types, Enforced at Runtime

import { App } from '@deepkit/app';
import { FrameworkModule } from '@deepkit/framework';
import { HttpBody, HttpQuery, HttpRouterRegistry } from '@deepkit/http';
import { Database } from '@deepkit/orm';
import { SQLiteDatabaseAdapter } from '@deepkit/sqlite';
import { AutoIncrement, Email, Maximum, MinLength, PrimaryKey, Unique } from '@deepkit/type';

// validation, serialization, database table and API docs in one type
class User {
    id: number & PrimaryKey & AutoIncrement = 0;
    created: Date = new Date();
    username: string & MinLength<3> & Unique = '';
    email: Email = '';
}

class AppDatabase extends Database {
    constructor() {
        super(new SQLiteDatabaseAdapter('app.sqlite'), [User]);
    }
}

const app = new App({
    providers: [AppDatabase],
    imports: [new FrameworkModule({ migrateOnStartup: true })],
});
const router = app.get(HttpRouterRegistry);

// POST /users {"username": "peter", "email": "[email protected]"}
router.post('/users', async (user: HttpBody<User>, database: AppDatabase) => {
    await database.persist(user);
    return user;
});

// GET /users?limit=10
router.get('/users', (database: AppDatabase, limit: HttpQuery<number> & Maximum<100> = 10) => {
    return database.query(User).limit(limit).find();
});

app.run();

$ curl -X POST localhost:8080/users -d '{"username": "pe", "email": "nope"}'
HTTP/1.1 400 Bad Request
{
  "message": "Validation error:\nusername(minLength): Min length is 3 caused by value \"pe\",\nemail(pattern): Pattern ^\\S+@\\S+$ does not match caused by value \"nope\"",
  "errors": [
    { "path": "username", "code": "minLength", "message": "Min length is 3", "value": "pe" },
    { "path": "email", "code": "pattern", "message": "Pattern ^\\S+@\\S+$ does not match", "value": "nope" }
  ]
}