A simple GraphQL API for managing books, built in Go and containerized with Docker. This project was initially learned from https://medium.com/@ferdousazad12/building-a-graphql-application-with-go-postgresql-and-docker-836db34f245c and then adapted with some changes.

Key files:

• main.go
• schema/schema.go
• handlers/book_handlers.go
• models/book.go
• utils/db.go
• config/config.go
• Dockerfile
• docker-compose.yml
• .env.example

Notable constructs:

• http.HandleFunc() wires the GraphQL HTTP endpoint at /graphql.
• graphql.Do() executes GraphQL operations.
• graphql.NewSchema() builds the executable schema from RootQuery and RootMutation.

Getting started

Prerequisites:

• Docker and Docker Compose installed
• Git

Setup and run with Docker Compose:

1. Copy env file: cp .env.example .env Edit DB_USER and DB_PASSWORD as needed.
2. Build and start: docker compose up --build
3. GraphQL endpoint: http://localhost:8080/graphql

Environment variables The app reads database settings from environment variables provided by Docker Compose. See docker-compose.yml and .env.example.

GraphQL schema overview

Type Book:

• id: Int
• title: String
• author: String
• publishedYear: Int

Queries:

• books: [Book]
• book(id: Int): Book

Mutations:

• createBook(title, author, publishedYear): Book
• updateBook(id, title, author, publishedYear): Book
• deleteBook(id): Book

Example operations

Query all books:

query {
  books {
    id
    title
    author
    publishedYear
  }
}

Query a book by ID:

query {
  book(id: 1) {
    id
    title
    author
    publishedYear
  }
}

Create a book:

mutation {
  createBook(title: "Clean Code", author: "Robert C. Martin", publishedYear: 2008) {
    id
    title
    author
    publishedYear
  }
}

Update a book:

mutation {
  updateBook(id: 1, title: "Clean Coder", author: "Robert C. Martin", publishedYear: 2011) {
    id
    title
    author
    publishedYear
  }
}

Delete a book:

mutation {
  deleteBook(id: 1) {
    id
    title
  }
}

cURL examples

POST a query:

curl -X POST http://localhost:8080/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"{ books { id title author publishedYear } }"}'

POST a mutation:

curl -X POST http://localhost:8080/graphql \
  -H "Content-Type: application/json" \
  -d '{"query":"mutation { createBook(title:\"Clean Code\", author:\"Robert C. Martin\", publishedYear:2008) { id title author publishedYear } }"}'

Local development (without Docker)

Ensure a local PostgreSQL instance is running and set env vars (DB_HOST, DB_PORT, DB_USER, DB_PASSWORD, DB_NAME). Then run:

go run ./main.go

Credits

Based on the tutorial above and modified for learning and experimentation. See implementation points in main.go, schema/schema.go, and containerization via Dockerfile and docker-compose.yml.

thanks to Ferdous Azad for the original tutorial!, check it out at https://medium.com/@ferdousazad12/building-a-graphql-application-with-go-postgresql-and-docker-836db34f245c

happy learning! ✌️