How to generate typed APIs with Cursor

1# codegen.yml
2overwrite: true
3schema: "src/schema/**/*.graphql"
4generates:
5  src/generated/graphql.ts:
6    plugins:
7      - typescript
8      - typescript-resolvers
9    config:
10      contextType: "../context#GraphQLContext"
11      mapperTypeSuffix: Model
12      useIndexSignature: true

1---
2description: GraphQL resolver conventions
3globs: "src/resolvers/**/*.ts"
4alwaysApply: true
5---
6
7## GraphQL Resolver Rules
8- ALWAYS import resolver types from @/generated/graphql
9- ALWAYS type resolvers using generated Resolvers type or individual QueryResolvers, MutationResolvers
10- ALWAYS type the context parameter as GraphQLContext from @/context
11- Handle nullable fields: return null explicitly, not undefined
12- Use DataLoader for N+1 prevention in nested resolvers
13- Throw GraphQLError for user-facing errors with proper extensions
14- NEVER use 'any' type in resolver arguments or return values
15- Validate mutation inputs before processing

1// Cursor Chat prompt (Cmd+L):
2// @src/generated/graphql.ts @src/schema/user.graphql
3// @src/context.ts
4// Generate the User query resolvers: user(id: ID!) and
5// users(page: Int, limit: Int). Use the generated
6// QueryResolvers type. Access the database through
7// context.db. Return types must match the schema exactly.
8
9import type { QueryResolvers } from '@/generated/graphql';
10import { GraphQLError } from 'graphql';
11
12export const userQueries: QueryResolvers = {
13  user: async (_parent, { id }, context) => {
14    const user = await context.db.user.findUnique({ where: { id } });
15    if (!user) {
16      throw new GraphQLError('User not found', {
17        extensions: { code: 'NOT_FOUND' },
18      });
19    }
20    return user;
21  },
22  users: async (_parent, { page = 1, limit = 20 }, context) => {
23    return context.db.user.findMany({
24      skip: (page - 1) * limit,
25      take: limit,
26    });
27  },
28};

1// Cursor Chat prompt (Cmd+L):
2// @src/generated/graphql.ts @src/context.ts
3// Generate the createUser and updateUser mutation resolvers.
4// Check that context.user exists (authenticated).
5// Validate email format. Use the generated MutationResolvers type.
6
7import type { MutationResolvers } from '@/generated/graphql';
8import { GraphQLError } from 'graphql';
9
10export const userMutations: MutationResolvers = {
11  createUser: async (_parent, { input }, context) => {
12    if (!context.user) {
13      throw new GraphQLError('Authentication required', {
14        extensions: { code: 'UNAUTHENTICATED' },
15      });
16    }
17    if (!input.email.includes('@')) {
18      throw new GraphQLError('Invalid email format', {
19        extensions: { code: 'BAD_USER_INPUT' },
20      });
21    }
22    return context.db.user.create({ data: input });
23  },
24};

1// Cursor Chat prompt (Cmd+L):
2// @src/generated/graphql.ts Generate the User field
3// resolver for 'posts' that loads the user's posts.
4// Use context.loaders.postsByUserId DataLoader to
5// prevent N+1 queries. Type it using UserResolvers.
6
7import type { UserResolvers } from '@/generated/graphql';
8
9export const userFieldResolvers: UserResolvers = {
10  posts: async (parent, _args, context) => {
11    return context.loaders.postsByUserId.load(parent.id);
12  },
13  fullName: (parent) => {
14    return `${parent.firstName} ${parent.lastName}`;
15  },
16};