graphql-scanner

GraphQL Scanner

Define your GraphQL types in separate files

✨ ✨

Introduction

A GraphQL server generally needs two things: a typeDefs string and a resolvers object.

• The typeDefs string contains the schema definitions,
• resolvers object describes how to resolve certain attributes of a type.

The problem is, both the typeDefs and resolvers can get huge and/or impractical to use.

Enter GraphQL Scanner! A tiny util that allows you to define each type (and their matching resolver) in a separate file.

Tested with Apollo Server, but should also work with GraphQL.js and express-graphql

Quickstart

Install the dependency

$ npm install graphql-scanner --save

Create a types directory

Create a 'types' directory in your project, and use it to store your GraphQL types.

For example:

├── types
|   ├── Query.js
|   └── TodoList.js
|   └── User.js
├── app.js

Define your types

Each type MUST expose an object containing two attributes:

• typeDef (String, required): the GraphQL schema definition of your type
• resolver (Object, optional): an object to resolve certain attributes of the type you've defined

For example:

types/Query.js

module.exports = {
  typeDef: `
      type Query {
        currentUser: User
      }
    `,
  resolver: {
    currentUser(_, args, ctx) {
      const { apikey } = ctx;
      return {
        firstName: "John",
        lastName: "Do",
        apikey
      };
    }
  }
};

types/User.js

module.exports = {
  typeDef: `
      type User {
        firstName: String!
        lastName: String
        apikey: String
        todoLists: [TodoList]
      }
    `,
  resolver: {
    todoLists(user, args, ctx) {
      return Promise.resolve([
        {
          subject: 'Holidays',
        }
      ]);
    }
  }
};

types/TodoList.js

module.exports = {
  typeDef: `
      type TodoList {
        subject: String!
        tasks: [String]
      }
    `,
  resolver: {
    tasks(todoList, arg, ctx)  {
      return Promise.resolve(['Fix a cab', 'Book a flight']);
    }
  }
};

Use the GraphQL Scanner

You need to pass the path to your directory that contain your types.

For example:

app.js:

const path = require('path');
const graphqlScanner = require('graphql-scanner');

// ...

const dir = path.join(__dirname, './types');
const { typeDefs, resolvers } = graphqlScanner(dir);
const server = new GraphQLServer({ typeDefs, resolvers });

The graphqlScanner(dir) expression scans your types and returns an object containing typeDefs and resolvers.

You can then pass these typeDefs and resolvers to your favourite GraphQL server library.

How does it work?

Check the code, it's less than 20 lines!

It uses require-all to load all modules in the dir you've passed as an argument

Then, it will iterate over all loaded modules and

• append each individual typeDef string to a typeDefs variable.
• add each individual resolver to a resolvers object as an attribute. The key of each attribute is the file name (minus extension) of the type

Finally, it will return an object: { typeDefs, resolvers }