A production GraphQL server is usually more than a schema and a few resolver functions. A clean architecture separates concerns between transport, GraphQL execution, application services, data access, and infrastructure.

A useful structure is:

HTTP / WebSocket Transport
          ↓
GraphQL Server
          ↓
Schema + Validation
          ↓
Resolvers
          ↓
Application Services
          ↓
Repositories / Data Sources
          ↓
Database / External APIs

For a Node.js application, a possible project structure is:

src/
  graphql/
    schema/
    resolvers/
  services/
  repositories/
  models/
  middleware/
  context/
  config/
  server.js

The exact structure is not mandatory. The important principle is separation of responsibilities.

GraphQL layer

Defines the API contract and coordinates execution.

Service layer

Contains application and business logic.

Repository/data-access layer

Handles persistence and external data access.

Infrastructure layer

Handles database connections, logging, configuration, queues, and other operational concerns.

Keeping these boundaries clear prevents resolver files from becoming large collections of database queries and business rules.