Graphql Cheatsheet

GraphQL schema defines the capabilities of a GraphQL API by specifying available types and their relationships. It serves as a contract between the client and server, documenting all possible queries, mutations, and subscriptions.

GraphQL queries allow clients to request exactly the data they need in a single request. Unlike REST, where multiple endpoints might be needed to fetch related data, GraphQL enables precise data selection with a declarative syntax that mirrors the shape of the response.

Mutations are operations that modify data on the server. Unlike queries which only read data, mutations create, update, or delete data. GraphQL mutations follow a specific structure to ensure predictable behavior and provide a clear contract for data modification.

GraphQL subscriptions provide a way to receive real-time updates from the server when data changes. Unlike queries and mutations, subscriptions maintain a persistent connection to the server, usually via WebSockets, allowing servers to push updates to subscribed clients.

Resolvers are functions that determine how to fetch the data associated with a specific field in a GraphQL schema. They are the bridge between the GraphQL operation and your data source, handling data fetching, transformation, and business logic.

GraphQL provides structured error handling mechanisms to manage various types of errors that can occur during query execution. Understanding how to properly validate inputs, handle errors, and control nullability is essential for building robust GraphQL APIs.

Authentication verifies user identity, while authorization determines what authenticated users can access. In GraphQL, these security layers can be implemented at various levels of the API to protect sensitive data and operations.