@beamf/graphql-schema-typescript

A GraphQL utility to generate Typescript from Schema Definition

This project is inspired by Apollo-codegen. Currently apollo-codegen only generate TypeScripts for GraphQL Client. The shape of the generated type is based on the client's query strings.

This module aim to do the Server counterpart: from a Schema Definition, generate the types to make it type-safed when developing GraphQL server (mainly resolvers)

Features

Generate Typescript from Schema Definition

Support Typescript string enum with fallback to string union (fallback not tested yet)

Convert GraphQL description into JSDoc

Also add deprecated field and reason into JSDoc

Generate TypeScripts to support writing resolvers

Usage

import { generateTypeScriptTypes } from 'graphql-schema-typescript';

generateTypeScriptTypes(schema, outputPath, options)
    .then(() => {
        console.log('DONE');
        process.exit(0);
    })
    .catch(err =>{
        console.error(err);
        process.exit(1);
    });

You can then bootstrap this script on your dev server, or use something like ts-node to execute it directly

• schema: your graphql schema
• outputPath: where the types is generated
• options: see GenerateTypescriptOptions

Type Resolvers

The file generated will have some types that can make it type-safed when writing resolver:

• Args type in your resolve function is now type-safed
• Parent type and resolve result is still any, but could be overwritten in your code

For example, if you schema is like this:

schema {
    query: RootQuery
}

type RootQuery {
    Users(input: UserFilter): [User!]!
    # ... some more fields here
}

input UserFilter {
    username: [String]
}

type User {
    firstName: String!
    # ... some more fields here
}

Then the tools will generate TypeScripts like this:

/**
 * This interface define the shape of your resolver
 * Note that this type is designed to be compatible with graphql-tools resolvers
 * However, you can still use other generated interfaces to make your resolver type-safed
 */
export interface GQLResolver {
  RootQuery?: GQLRootQueryTypeResolver;
  User?: GQLUserTypeResolver;
}

export interface GQLRootQueryTypeResolver {
  Users?: RootQueryToUsersResolver;
}

export interface RootQueryToUsersArgs {
  Users?: GQLUserFilter;
}

export interface RootQueryToUsersResolver<TParent = any, TResult = any> {
  (parent: TParent, args: RootQueryToUsersArgs, context: any, info: GraphQLResolveInfo): TResult;
}

In this example, if you are not using graphql-tools, you can still use RootQueryToUsersResolver type to make your args type safed.

TODO

• More detailed API Documentation
• Integrate with Travis CI

Change log

• v1.0.6:

  • Generate TypeScript for resolvers. See Type Resolvers

• v1.0.4:

  • If types is generated under global scope, use string union instead of string enum

• v1.0.2:

  • Change default prefix from GQL_ to GQL
  • Add config options: allow to generate types under a global or namespace declaration