TypeScript GraphQL Backend

This is a sample Node.js backend to provide a GraphQL API to fetch the list of companies, cities, and specialties.

Project structure

├── config
|  ├── default.json
|  └── production.json
├── jsons
|  └── db.json
├── src
|  ├── db
|  |  ├── index.ts
|  |  └── types
|  |  |  ├── City.d.ts
|  |  |  ├── Company.d.ts
|  |  |  └── Speciality.d.ts
|  ├── graphql
|  |  ├── index.ts
|  |  └── object-types
|  |  |  ├── city.ts
|  |  |  ├── company.ts
|  |  |  ├── index.ts
|  |  |  └── speciality.ts
|  └── server.ts
└── tsconfig.json

This directory tree has been generated by the tree CLI.

config

The config/ directory contains the JSON-based environment configuration files for the application. Using the config package, we can access one of these JSON files. This package uses NODE_ENV environment variable to provide one of these JSON files through the config.get() API. We have saved server configuration and other settings.

jsons

The jsons/ directory contains db.json to store companies, cities and specialities in the JSON format. This file act as a temporary database and it is used by lowdb to provide an easy API to perform persistent CRUD operations.

src

The src/ directory contains the source-code of our application.

The db directory contains db/index.ts file which exports lowdb API wrapped around jsons/db.json file for the CRUD operations. The lowdb package provides high-level interface to work with JSON files using lodash functions.
The graphql directory contains GraphQL related programs. The graphql/types directory contains GraphQL object types for the Company, City the company operates in and Speciality a company has. The graphql/index.ts file exposes the GraphQL schema.
The server.ts file contains Express server implementation. The GraphQL API is exposed on /graph route using express-graphql middleware.

Other Features

We use $db and $graphql alias to target src/db and src/graphql directories respectively. This is done using module-alias package. These aliases are configured inside server.ts file.
We use cross-env package to run NPM scripts. Since Windows OS does not support Unix-style environment variable declaration in commands, this is very useful for cross-platform use.

Run/Build Application

Start Express server in Development mode

$ npm run start:dev
$ open http://127.0.0.1:3000/graph

This command internally runs nodemon command. Using nodemon.json configuration, we run server.ts with ts-node and watch for any file changes in the src directory. The API URL should be displayed in the terminal when the server starts.

Build Project and Run in Production mode

$ npm run build

This command builds the entire src directory and outputs compiled JavaScript files in the dist directory. Build configuration is present inside tsconfig.json.

Ideally dist directory should be ignored but I have kept it in the commit just for a better understanding of the output.

$ npm run start
$ open http://127.0.0.1:8080/graph

This command starts the dist/server.js file with node. However, it would be ideal to run this server in the backend. We can do that using $ npm run start:daemon command. This starts the server with pm2 and scales the instance to 3 parallel processes.

Improvements

We can create a better wrapper around db instance and provide methods to process data rather than doing inside GraphQL resolvers.
We can use type-graphql to modularize GraphQL objects and their resolvers.

thatisuday / ts-graphql-demo