GraphQL Glossary

This is a glossary of GraphQL related terms with examples from Insites implementations.

Argument

A set of key-value pairs attached to a specific field. Arguments can be literal values or variables.

Alias

An alternative name given to the result of a field to avoid conflicts during data fetching.

Directive

A declaration prefixed with an character that encapsulates programming logic for query execution on the client or server. There are built-in directives such as or . Directives can be used for features such as authentication, incremental data loading, etc.

Document

A file or request string that contains one or multiple definitions of a GraphQL type system and can be interpreted by a GraphQL execution engine.

Field

A unit of data you are asking for in a Schema, which ends up as a field in your JSON response data.

Fragment

A selection set that can be reused in multiple query operations. A GraphQL fragment is a shared piece of query logic.

GraphQL Playground

An in-browser IDE for GraphQL development and workflow. Added benefits exist such as theme change, automatic schema reloading, HTTP headers configuration, query history and GraphQL subscription support.

Introspection

A technique to provide detailed information about a GraphQL API's schema. Types and fields used in introspection are prefixed with two underscores.

Mutation

An operation for creating, modifying and destroying data.

Object Type

A type in a GraphQL schema that has fields.

is an Object type in the example above.

Operation

A query, mutation, or subscription that can be interpreted by a GraphQL execution engine.

Operation Name

A name for a single query, mutation, or subscription. Identifying a query or mutation by name is very useful for logging and debugging when something goes wrong in a GraphQL server.

Query

A read-only fetch operation to request data from a GraphQL service.

Schema

A GraphQL schema is at the centre of any GraphQL server implementation and describes the functionality available to the clients which connect to it.

Schema Definition Language

The syntax for writing GraphQL Schemas. It is otherwise known as Interface Definition Language. It is the lingua franca shared by all for building GraphQL APIs regardless of the programming language chosen.

Scalar Type

A type that qualifies the data a GraphQL field resolves. GraphQL ships with some scalar types out of the box; , , , , , and . However, a custom scalar type such as can be specified in a GraphQL service implementation.

Type System

A collection of types that characterises the set of data that can be validated, queried and executed on a GraphQL API.