Real-World GraphQL Project: Production-Ready API

Combine the concepts from the course into a realistic GraphQL application with authentication, CRUD operations, MongoDB, pagination, filtering, DataLoader, authorization, testing, and production practices.

Project Requirements and Architecture

Build a task-management GraphQL API where users can create accounts, authenticate, manage projects, create tasks, assign tasks to members, filter and paginate tasks, and receive appropriate authorization errors.

The project should use a layered architecture consisting of GraphQL schema and resolvers, application services, data-access modules, authentication, authorization, DataLoader, and MongoDB.

The goal is not simply to create CRUD endpoints but to demonstrate how GraphQL concepts fit together in a realistic backend.

Designing the Domain Model

The application can contain entities such as User, Project, and Task.

A User can belong to multiple projects. A Project can contain multiple tasks. A Task can have an assignee and a creator.

Before writing resolvers, define ownership and relationships clearly. Decide which fields are required, which fields are nullable, and which relationships require authorization checks.

Designing the GraphQL Schema

The schema should expose queries for retrieving the current user, projects, and tasks. Mutations should handle project creation, task creation, task updates, and deletion.

Use input objects for complex mutation arguments and connection-style pagination for collections. Avoid exposing database-specific implementation details directly through the API schema.

Adding Authentication and Authorization

Authentication can establish the current user from a signed token. The GraphQL context can expose the authenticated user to resolvers and services.

Authorization rules should then determine whether the user can access a project or modify a task. For example, project members may read project data while only project administrators may delete the project.

These checks should be enforced on the server rather than relying on frontend controls.

Building Resolvers and Services

Resolvers should remain relatively thin. They translate GraphQL arguments into calls to application services. Services should contain business rules and coordinate data access.

This separation makes the application easier to test and prevents GraphQL-specific concerns from spreading throughout the domain layer.

Adding DataLoader to Relationships

When a task list includes an assignee field, naive nested resolution can create the N+1 problem. Introduce a request-scoped DataLoader that batches user lookups.

The same technique can be applied to project membership, task creators, or other frequently accessed relationships.

Adding Pagination and Filtering

Task lists should require bounded pagination. Filtering can support fields such as status, priority, project, and assignee. Sorting should use a deterministic order so pagination remains stable.

For large datasets, cursor-based pagination is usually preferable because it can provide more predictable behavior as records are inserted or removed.

Example Task Query

The client can request a page of tasks while selecting only the fields needed by the interface.

Task List Query

query ProjectTasks(
  $projectId: ID!
  $first: Int!
  $after: String
) {
  project(id: $projectId) {
    id
    name
    tasks(first: $first, after: $after) {
      edges {
        cursor
        node {
          id
          title
          status
          assignee {
            id
            name
          }
        }
      }
      pageInfo {
        hasNextPage
        endCursor
      }
    }
  }
}

💡 The query demonstrates nested selection, variables, cursor pagination, and relationship loading while allowing the server to return exactly the fields required by the client.

Testing the Complete API

Create tests for successful authentication, unauthorized access, project creation, task creation, pagination, filtering, and relationship resolution.

Include negative tests such as attempting to access another user's private project or attempting an administrator-only mutation as a regular member.

Integration tests should execute complete GraphQL operations rather than testing only isolated resolver functions.

Making the Project Production Ready

Before considering the project complete, add request logging, error handling, rate limiting, query complexity protection, bounded pagination, health checks, graceful shutdown, environment validation, and database indexes.

The final system should also have automated tests and a deployment process that validates schema changes before production.