Facade

Facades provide a public API for cross-module access. When one module needs to use functionality from another module, it should inject a Facade, not a Service or Repo.

Invalid cross-module access will result in a build error and runtime exception.

Example

users/users.facade.ts

const Users = Vla.createModule('Users')

class UserFacade extends Users.Facade {
  service = this.inject(UserService)

  async getUser(id: string) {
    return this.service.findById(id)
  }

  async hasPermission(userId: string, permission: string) {
    return this.service.checkPermission(userId, permission)
  }
}

// posts/posts.service.ts
const Posts = Vla.createModule('Posts')

class PostService extends Posts.Service {
  users = this.inject(UserFacade) // ✅ Cross-module access

  async createPost(userId: string, data: PostData) {
    const canPost = await this.users.hasPermission(userId, 'post:create')

    if (!canPost) {
      throw new Error('Permission denied')
    }

    // Create post...
  }
}

When to Use

• Public interface for cross-module dependencies

Reference

Scope

transient - New instance created per usage.

Properties

static readonly scope = 'transient'

Methods

Facades inherit the inject() method.

Characteristics

• Scope: transient (new instance per usage)
• Purpose: Public interface for modules
• Can inject: Services, Repos (same module), other Facades, Resources, Contexts
• Best practices: Only expose what other modules need