GraphQL Reference

Getting Started with GraphQL — what GraphQL is, the specification it follows, how it differs from REST, and running a first schema and query.

Queries and Fields — the query operation, selecting fields, aliases, nested selections, and arguments.

Variables, Directives & Fragments — parameterizing queries with variables, the built-in @include/@skip directives, and reusing selections with fragments.

Mutations — the mutation operation, input types, and sequential execution of top-level mutation fields.

Subscriptions — the subscription operation, event streams, and transports for pushing incremental updates to clients.

Introspection — querying a schema’s own type system through the schema and type meta-fields.

Schema and Type System — the type system (scalars, objects, enums, lists, non-null), the schema definition language, and the root operation types.

Interfaces, Unions & Inputs — abstract types for polymorphic results and structured input types for arguments.

Directives — declaring and using custom schema and query directives, including the working-draft @defer/@stream and @oneOf directives.

GraphQL Schema Design — naming conventions, nullability choices, connection-style pagination, and evolving a schema without breaking clients.

Execution & Resolvers — how a query is executed field by field, resolver functions, default resolvers, and resolver arguments.

Validation — validating a request document against the schema before execution begins.

Response and Error Handling — the response envelope, partial results, and the errors array and its extensions.

Serving GraphQL over HTTP — the GraphQL-over-HTTP conventions for request and response encoding, status codes, and content negotiation.

Pagination — offset and cursor-based pagination patterns and the connection model, and how it compares to keyset pagination in SQL and NoSQL stores.

Global Object Identification — the Node interface and globally unique object identifiers.

GraphQL Caching — caching strategies for a query language without cacheable URLs, from normalized client caches to persisted queries.

Performance & N+1 — the N+1 resolver problem and batching it away with the DataLoader pattern.

Security and Demand Control — query depth and complexity limits, rate limiting, and guarding against expensive or malicious queries.

Authorization — enforcing field- and object-level access control from within resolvers and directives.

Federation — composing multiple subgraphs into a single supergraph.

Tips: When to Use GraphQL or a Typical REST API — a decision-oriented comparison of GraphQL and a typical REST API, including query-plan cost and index coverage, and when to deploy each.

Spring Boot: Getting Started with GraphQL — adding Spring for GraphQL to a Spring Boot application and serving a first schema.

Spring Boot: Annotated Controllers — mapping queries, mutations, and subscriptions to @Controller handler methods.

Spring Boot: Data Loading & Integration — batch loading with BatchLoaderRegistry, and integrating a data layer behind resolvers.

Spring for GraphQL: Transports, Security, and Testing — HTTP, WebSocket and RSocket transports, securing endpoints, and testing with GraphQlTester.

Python: Getting Started — the Python GraphQL ecosystem and choosing between the Strawberry and Ariadne approaches.

Strawberry with FastAPI — mounting a Strawberry schema onto a FastAPI application.

Strawberry — Schema and Features — defining a schema with Strawberry’s type annotations, and its subscriptions, permissions, and dataloader support.

Ariadne: Schema-First GraphQL — the schema-first approach with Ariadne and its ASGI/FastAPI integration.

GraphQL Clients: Choosing an Approach — what a GraphQL client adds over a plain HTTP request, and choosing among the major client libraries.

Apollo Client Configuration — configuring Apollo Client’s networking, normalized cache, and pagination helpers.

Other GraphQL Clients: urql, Relay, JVM, and Python — urql, Relay, JVM clients such as graphql-java, and the Python gql client.

GraphQL Cheat Sheet — a single-page, printable summary of everything in this section, with a downloadable PDF.