Resource

Resources are long-lived infrastructure clients like database pools, cache connections, API clients, or configuration objects.

Example

class Database extends Vla.Resource {
  static readonly unwrap = "db"

  db = this.devStable("prisma", () => new PrismaClient())
}

class UserRepo extends Vla.Repo {
  // Thanks to unwrap, this injects the 'db' property directly
  db = this.inject(Database)

  async findAll() {
    return this.db.user.findMany()
  }
}

When to Use

• Database connections
• Cache clients
• Configuration singletons

Reference

Scope

singleton - Single instance created and cached forever.

Properties

static readonly scope = 'singleton'
static readonly unwrap?: PropertyKey

Special Property: unwrap

The unwrap static property allows injectors to receive a specific property instead of the entire Resource instance.

class Database extends Vla.Resource {
  static readonly unwrap = "client"

  client = new PrismaClient()
}

class UserRepo extends Vla.Repo {
  // Injects the 'client' property directly, not the Database instance
  db = this.inject(Database)

  async findAll() {
    return this.db.user.findMany() // this.db is PrismaClient
  }
}

Characteristics

• Scope: singleton (single instance forever)
• Purpose: Database connections, cache clients, configuration
• Can inject: Other Resources, Contexts
• Best practices: Use for expensive-to-create resources; implement cleanup methods

Note

Resources can be injected cross-module.