GraphQL and Apollo

When using Apollo Client with GraphQL in a TypeScript-based React project, typing your queries and mutations is crucial for leveraging TypeScript's type-checking capabilities. This ensures that the data you query or mutate aligns with your GraphQL schema.

Apollo Client uses @apollo/client in combination with GraphQL code generation tools to automatically generate TypeScript types. These types correspond to the queries and mutations you define, making your code more robust and less prone to errors.

Every time you run the code generator (using npx graphql-codegen), it scans your GraphQL operations and generates corresponding TypeScript types.

For instance, if you have a query:

query GetUsers {
  users {
    id
    name
    email
  }
}

GraphQL Code Generator creates a TypeScript type for the query result, which can then be imported into your components:

import { GetUsers } from './generated/graphql';

In this example, GetUsers is a type-safe hook generated from your GraphQL query. It automatically infers the types for data, loading, and error, based on the GraphQL schema.