Vapor Best Practices

1. Concurrency

• ALWAYS use Swift Concurrency (async/await) over EventLoopFuture.
• Use req.application.asyncController patterns if using custom executors, but standard async route handlers are preferred.

2. Controllers & Routing

• Organize routes into RouteCollection conformances.
• Do not put logic in routes.swift; delegate immediately to a Controller.
• Group routes by feature (e.g., UsersController, AuthController).

3. Fluent (Database)

• Use @Parent and @Children property wrappers correctly.
• Always use DTOs (Data Transfer Objects) implementation Content for API requests/responses. NEVER return a Fluent Model directly to the client.
• Run migrations via app.migrations.add(...).

4. Environment

• Use Environment.get("KEY") for configuration.
• Support Production vs Development modes explicitly in configure.swift.

Example Route

func boot(routes: RoutesBuilder) throws {
    let users = routes.grouped("users")
    users.get(use: index)
}

@Sendable
func index(req: Request) async throws -> [UserDTO] {
    let users = try await User.query(on: req.db).all()
    return users.map { $0.toDTO() }
}