GraphQL to TypeScript Resolver Generator

What is GraphQL to TypeScript Resolver Generator?

In a GraphQL server built with TypeScript, resolvers are the functions that fetch data for each field in your schema. Writing type-safe resolvers from scratch requires manually defining the parent, arguments, and return types for every Query, Mutation, and Subscription field — a process that is both repetitive and prone to type mismatches. This tool reads your GraphQL Schema Definition Language (SDL) and generates a complete set of TypeScript resolver interfaces and optional implementation stubs. It produces separate interfaces for QueryResolvers, MutationResolvers, and SubscriptionResolvers, each with fully typed method signatures. Input types are converted to TypeScript interfaces, and the Context type is included so you can pass request-scoped data (like the current user or database connections) through every resolver. The optional stubs give you a working starting point with TODO comments, so you can fill in business logic without worrying about the type signatures.

How to Use

1. Paste your GraphQL schema SDL into the input area — include Query, Mutation, Subscription, and all input/object type definitions
2. Toggle the "Include resolver stubs" checkbox if you want boilerplate implementation code with TODO placeholders
3. Click "Generate TypeScript" to parse the schema and produce resolver type definitions
4. Switch between the Types and Resolvers tabs to inspect the generated interfaces and stub code
5. Copy the output into your server project and implement the resolver functions by replacing the TODO placeholders
6. Customize the Context interface to include your authentication data, database connections, or other services

Tips & Best Practices

• Keep the generated types in a separate file (e.g., types/resolvers.ts) so you can regenerate them without touching your implementation
• Extend the Context interface with your actual context shape — add fields like user, prisma, or logger that your resolvers need
• For Subscription resolvers, the generated code uses AsyncIterator — pair this with a pub/sub library like graphql-subscriptions for real-time events
• If you use DataLoader for batching, add it to the Context interface so every resolver can access it
• After implementing resolvers, run tsc --noEmit to verify there are no type errors before deploying

Frequently Asked Questions

Real-world Examples

type Query {
  posts(limit: Int): [Post!]!
}

type Mutation {
  createPost(input: CreatePostInput!): Post!
}

type Post { id: ID! title: String! content: String }

input CreatePostInput { title: String! content: String }

export interface Context {
  prisma: PrismaClient;
  user?: User;
}

export interface Post {
  id: string;
  title: string;
  content?: string;
}

export interface CreatePostInput {
  title: string;
  content?: string;
}

export interface QueryResolvers {
  posts: (parent: unknown, args: { limit?: number }, context: Context) => Post[] | Promise<Post[]>;
}

export interface MutationResolvers {
  createPost: (parent: unknown, args: { input: CreatePostInput }, context: Context) => Post | Promise<Post>;
}

// Resolver stubs
export const resolvers: Resolvers = {
  Query: {
    posts: async (_parent, { limit }, _context) => {
      // TODO: Implement posts resolver
      throw new Error('Resolver not implemented: posts');
    },
  },
  Mutation: {
    createPost: async (_parent, { input }, _context) => {
      // TODO: Implement createPost resolver
      throw new Error('Resolver not implemented: createPost');
    },
  },
};

type Subscription {
  onMessage(roomId: ID!): Message!
}

type Message { id: ID! text: String! sender: String! }

export interface SubscriptionResolvers {
  onMessage: {
    subscribe: (parent: unknown, args: { roomId: string }, context: Context) => AsyncIterator<Message>;
  };
}

// Implementation with graphql-subscriptions:
// import { PubSub } from 'graphql-subscriptions';
// const pubsub = new PubSub();
// Subscription: {
//   onMessage: {
//     subscribe: (_, { roomId }) => pubsub.asyncIterator(`MESSAGE_${roomId}`),
//   },
// }

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