Repo

Repos (repositories) handle data access and external adapters. They’re the only layer that should communicate with databases, APIs, or other external services.

Example

class PostRepo extends Vla.Repo {
  db = this.inject(Database)

  // Memoized queries
  findById = this.memo((id: string) => {
    return this.db.posts.find({ id })
  })

  findByAuthor = this.memo((authorId: string) => {
    return this.db.posts.findMany({ authorId })
  })

  // Write operations (not memoized)
  async create(data: PostData) {
    const post = await this.db.posts.create({ data })

    // Prime the cache
    this.findById.prime(post.id).value(post)

    return post
  }

  async update(id: string, data: Partial<PostData>) {
    const post = await this.db.posts.update({ where: { id }, data })

    // Bust the cache
    this.findById.bust(id)

    return post
  }
}

When to Use

• Database queries
• External API calls
• File system access

Reference

Scope

invoke - Shared within a request.

Properties

static readonly scope = 'invoke'

Methods

Repos inherit both inject() and memo() methods.

memo()

memo<Args extends unknown[], R>(
  fn: (...args: Args) => R
): Memoized<Args, R>

Creates a memoized method that caches results per request.

class UserRepo extends Vla.Repo {
  db = this.inject(Database)

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

// Multiple calls with same ID = only one database query
await repo.findById('1') // Executes query
await repo.findById('1') // Returns cached result

See Memoization guide for details.

Characteristics

• Scope: invoke (shared within a request)
• Purpose: Data access, external API calls
• Can inject: Resources, Contexts
• Best practices: Memoize reads, not writes; no business logic