graphql-engine/community/boilerplates/remote-schemas/rest-wrapper

REST wrapper - Boilerplate to write a GraphQL server that wraps a REST API

This boilerplate gives an example of writing a GraphQL service to wrap some pre-existing REST API. You can add this REST wrapper as a Remote Schema in Hasura.

Stack

Node 8.10

Apollo Server (GraphQL framework)

REST API

The REST API is implemented in my-rest-api folder. It has the following APIs:

GET /users
GET /users/:userId
POST /users

The GET /users endpoint also takes an optional query param i.e. GET /users?name=abc and the POST /users endpoint expects a valid JSON payload in the body.

GraphQL API

We will convert the above REST API into the following GraphQL API:

type User {
  id:       String!
  name:     String!
  balance:  Int!
}

type Query {
  getUser(id: String!): User
  users(name: String): [User]
}

type Mutation {
  addUser(name: String!, balance: Int!): User
}

How to wrap

In our GraphQL service, we have defined a new API for each REST endpoint. This is what our mapping looks like:

REST	GraphQL
GET /users	users (name: String) : [User]
GET /users/:userId	getUser(id: String!): User
POST /users	addUser(name: String!, balance: Int!): User

We would have to write a resolver for each API. This is what a typical resolver looks like, for e.g getUser :

getUser: async (_, { id }) => {
    return await getData(restAPIEndpoint + '/users/' + id);
}

Deployment (Using Heroku)

You need a Heroku account and heroku-cli installed. Execute the following commands in a terminal:

1. Log into Heroku

heroku login

2. Create REST API app

# in my-rest-api directory (community/boilerplates/remote-schemas/rest-wrapper/my-rest-api)
heroku create

3. Deploy REST API app

git push heroku master

4. The above step will return an endpoint for your REST API. Update the constant restAPIEndpoint in index.js with this endpoint.

5. Create GRAPHQL API app

# in current directory (community/boilerplates/remote-schemas/rest-wrapper)
heroku create

6. Deploy GRAPHQL API app

git push heroku master

The final step will also return a HTTPS URL in the output. Now, you can go to Hasura console and add this URL as a Remote Schema to allow querying it via Hasura.