graphql-example

Intuitive GraphQL Resolver Example - Application example using RawModel.js as GraphQL rootValue on steroids.

GraphQL is a modern replacement for the well known REST API server. This is a pure GraphQL server application - an example API server.

Features

This example uses Node.js v7 and MongoDB.

• GraphQL rootValue using RawModel.js.
• Nested schema.
• Print GraphQL schema from command-line.
• Execute GraphQL schema from command-line.
• Input data validation.
• Context-aware models.
• Graphql HTTP server.
• MongoDB connector (an example how to use a database connector).

Pre-requisites

• Make sure you are using Node.js v7+.
• Install and start MongoDB server.

Build Setup

# install dependencies
npm install

# start the server (GraphiQL is started at http://127.0.0.1:3000)
npm start

# use nodemon in development to automatically reload the server on changes
npm install -g nodemon
nodemon --exec npm start

# run GraphQL query from command-line
npm run exec '{getUsers {id name}}'

# run tests
npm test

Run

npm start

Starts GraphiQL server at http://127.0.0.1:3000/

Query Examples

mutation { # create new user
  createUser(name: "") {
    id
    name
    errors {
      path
      errors {
      	validator
      	message
      	code
      }
    }
  }
}

query { # get users
  getUsers(skip: 0, limit: 5) {
    id
    name
  }
}

Architecture

|- /config    - config files
|- /scripts   - scripts that can be executed from CLI (used by `package.json`)
|- /src
  |- /graph`    - GraphQL application
  |- /http      - HTTP server
  |- /lib       - general helpers (e.g. Mongo DB connector)
  |- index.js   - application main file
- /tests        - tests written in [ava](https://github.com/avajs/ava) framework

The application exports two main classes - Graph (GraphQL application - src/http) and HTTP (HTTP server - src/graph). Each class represents a stand-alone application. You could create two separated npm packages from this to further split your code to responsibilities.

The scripts in the ./src/scripts folder use these classes to print GraphQL schema, execute GraphQL query and start the HTTP server from the command-line. These scripts are used by the package.json file thus you can use the npm run {script-name} commands.

Graph application describes your data model and provides a communication layer. HTTP application exposes GraphQL application over HTTP thus users can use the GraphQL application as your API endpoint.

The HTTP server is based on express-graphql which is a bridge to communicate with a GraphQL application via Express HTTP server. You could substitute this with koa-graphql or koa-graphql-next. The express-graphql middleware includes a GraphiQL user interface which is a generic interface for running GraphQL queries and mutations (for use in development).

Graph application exposes the API over the GraphQL schema defined in ./src/graph/schema/index.graphql. It uses the RawModel.js for describing and validating input data. To keep the example simple, we only have two models here where the Root model represents a GraphQL resolver - the rootValue for GraphQL.

GraphQL Clients

Your front-end application will need a GraphQL client to communicate with a GraphQL server. You can also use a raw browser's fetch to post data to the GraphQL server.

Popular GraphQL clients (you can add your own):

• FetchQL
• lokka
• apollo-client

Tutorials

Node.js tutorials: Node.js Cheatsheet