GraphQL API Design — Complete Guide

04 Relationships

Introduction to GraphQL API Design

Explore GraphQL fundamentals including its declarative data-fetching model, strongly typed schema system, single-endpoint architecture, and how it compares to REST for modern API development.

Schema Design — Complete Guide

Learn GraphQL schema design using SDL, type definitions, root types (Query, Mutation, Subscription), schema-first vs code-first approaches, naming conventions, and documentation best practices.

Types: Object, Scalar, and Enum

Explore GraphQL type system fundamentals including object types with fields, built-in and custom scalar types (String, Int, Float, Boolean, ID, Date, JSON), and enum types with named values.

Queries in GraphQL — Complete Guide

Write GraphQL queries to fetch data using fields, arguments, aliases, fragments, and variables. Understand query execution, root resolver patterns, and response shape matching.

Mutations in GraphQL — Complete Guide

Learn GraphQL mutation patterns for creating, updating, and deleting data. Understand input types, return payloads, optimistic updates, and sequential execution guarantees compared to queries.

Subscriptions in GraphQL — Complete Guide

Implement real-time data streaming with GraphQL subscriptions using WebSocket transport. Learn subscription definitions, event-based resolvers, pub/sub patterns, and client-side subscription handling.

Resolvers in GraphQL — Complete Guide

Implement GraphQL resolvers that map schema fields to data sources. Learn resolver signatures, parent chain, arguments, context, field-level vs type-level resolvers, and batched data loading.

Input Types in GraphQL — Complete Guide

Structure mutation arguments with GraphQL input types. Learn input type definition, nested inputs, required vs optional fields, default values, and best practices for reusable input schemas.

Arguments in GraphQL — Complete Guide

Pass arguments to GraphQL fields for filtering, sorting, pagination, and data transformation. Learn argument definitions, required vs optional, default values, and argument validation patterns.

Directives in GraphQL — Complete Guide

Use GraphQL directives to annotate schema elements and transform query execution. Learn built-in directives (@deprecated, @skip, @include), custom schema directives, and directive location restrictions.

Interfaces and Unions in GraphQL

Model polymorphic relationships with GraphQL interfaces and unions. Learn interface fields, implementing types, union members, inline fragments, and __typename for runtime type discrimination.

Error Handling in GraphQL

Implement structured error handling in GraphQL APIs using UserError types, error codes, partial responses, custom error formatting, and the errors array in GraphQL responses.

Authentication in GraphQL — Complete Guide

Secure GraphQL APIs with authentication strategies including JWT tokens, OAuth2, API keys, and session-based auth. Learn token verification in context, WebSocket auth for subscriptions, and auth middleware patterns.

Authorization in GraphQL — Complete Guide

Implement fine-grained authorization in GraphQL APIs using role-based access control (RBAC), attribute-based access control (ABAC), field-level permissions, and authorization directives.

DataLoader and the N+1 Problem

Solve the GraphQL N+1 query problem using DataLoader for batching and caching database queries. Learn batch functions, per-request caching, and loader patterns for relational data.

Pagination and Relay Connections — Complete Guide

Implement cursor-based pagination in GraphQL using the Relay Connection specification. Learn edges, nodes, pageInfo, cursors, forward/backward pagination, and connection arguments.

Introduction to Apollo Federation

Build a distributed GraphQL architecture with Apollo Federation. Learn federated schemas, entities, @key directive, resolvers, gateway setup, and composing multiple sub-graphs into a unified supergraph.

Security: Depth Limiting and Query Cost

Secure GraphQL APIs against abusive queries using depth limiting, query complexity analysis, rate limiting, persisted queries, and timeout configuration to prevent denial of service attacks.

GraphQL Project: Build a Complete API

Build a complete GraphQL API project integrating schema design, types, relationships, queries, mutations, subscriptions, authentication, authorization, DataLoader, pagination, and security.