GraphQL Schema to TypeScript Types & Resolvers

Convert GraphQL Schema Definition Language (SDL) into type-safe TypeScript interfaces and resolver boilerplate.

Presets:

GraphQL Schema (SDL)

Generated TypeScript Interfaces

export interface User {
  id: string;
  username: string;
  email: string;
  bio: string | null;
  followersCount: number;
  role: Role;
  posts: Array<Post>;
}

export interface Post {
  id: string;
  title: string;
  content: string;
  published: boolean;
  author: User;
  likes: number;
  tags: Array<string> | null;
}

export type Role = 
  | 'ADMIN'
  | 'MODERATOR'
  | 'USER';

export interface Query {
  getUser: ID!): User | null;
  listPosts: Int): [Post!];
}

export interface Mutation {
  createPost: String! content: String!): Post;
}

GraphQL Resolvers Boilerplate

// Apollo / GraphQL Resolvers
import type { Resolvers } from './types';

export const resolvers = {
  Query: {
    getUser: async (_parent, _args, _context) => {
      // TODO: Implement getUser
      return null as any;
    },
    listPosts: async (_parent, _args, _context) => {
      // TODO: Implement listPosts
      return null as any;
    },
  },
  Mutation: {
    createPost: async (_parent, _args, _context) => {
      // TODO: Implement createPost
      return null as any;
    },
  },
};

Type Safety with GraphQL and TypeScript

Building full-stack GraphQL architectures requires synchronizing schema definitions with backend resolver types and frontend client interfaces. Converting GraphQL Schema Definition Language (SDL) directly into TypeScript interfaces ensures end-to-end type safety, preventing runtime null pointer exceptions and schema regressions.

GraphQL vs TypeScript Type Mapping

Scalars: String and ID map to TypeScript string. Int and Float map to number. Boolean maps to boolean.
Nullability: In GraphQL, fields are nullable by default (e.g. title: String $\rightarrow$ title: string | null). Exclamation points denote required fields (e.g. id: ID! $\rightarrow$ id: string).
Arrays: [Post!]! represents a non-null list of non-null Post objects (Array<Post>).