Putting Everything Together

Now that we’ve covered Actions, Services, Repos, and Resources, let’s see them work together in a complete example.

The Complete Picture

import { Vla } from 'vla'

// Resource: Long-lived database client
class Database extends Vla.Resource {
  static readonly unwrap = "db"
  db = this.devStable("db", () => new DbClient())
}

// Repo: Data access with memoization
class UserRepo extends Vla.Repo {
  db = this.inject(Database)

  findById = this.memo((id: string) => {
    return this.db.users.find({ id })
  })
}

// Service: Business logic and authorization
class UserService extends Vla.Service {
  repo = this.inject(UserRepo)
  session = this.inject(SessionService)

  async getProfile(userId: string) {
    // Authorization
    if (this.session.currentUserId !== userId) {
      throw new Error('Unauthorized')
    }

    // Data access through repo
    const user = await this.repo.findById(userId)

    // Transform for frontend
    return {
      name: user.name,
      email: user.email,
      joinedAt: user.createdAt
    }
  }
}

const SessionContext = Vla.createContext<{
  cookies: Cookies
}>()

class SessionService extends Vla.Service {
  sessionCtx = this.inject(SessionContext)

  get currentUserId() {
    const { userId } = parseSession(this.sessionCtx.cookies.get('session_id'))
    return userId
  }
}

// Action: Entry point from framework
class ShowUserProfile extends Vla.Action {
  users = this.inject(UserService)

  async handle(userId: string) {
    return this.users.getProfile(userId)
  }
}

// Invoke from your framework
const profile = await ShowUserProfile.invoke('user-123')

Growing Your Application

• As your application grows, you can organize code into Modules and use Facades for cross-module communication. Learn more in Modules and Facades.
• Learn more about recommended File Structure.