Netflix DGS Spring Boot Example

This project demonstrates how to use Netflix DGS (Domain Graph Service) with Spring Boot to build a GraphQL API. The project includes a simple library management system with entities such as Book, Author, and Reader.

Table of Contents

• Netflix DGS Spring Boot Example
  • Table of Contents
  • Prerequisites
  • Getting Started
    • Clone the Repository
    • Build the Project
    • Run the Application
  • Project Structure
  • GraphQL Schema
  • Data Fetchers
    • AuthorDataFetcher
    • BookDataFetcher
    • ReaderDataFetcher
  • Testing the API
  • License

Prerequisites

• JDK 21
• Docker (for PostgreSQL)
• Gradle

Getting Started

Clone the Repository

git clone https://github.com/maulikam/netflix-dgs-example.git
cd netflix-dgs-spring-boot-example

Build the Project

Make sure you have Gradle installed, then build the project:

./gradlew clean build

Run the Application

To start the PostgreSQL database using Docker, run:

docker-compose up -d

Then run the Spring Boot application:

./gradlew bootRun

The application will start and run on http://localhost:9191.

Project Structure

netflix-dgs-spring-boot-example
│
├── build.gradle
├── docker-compose.yml
├── src
│   ├── main
│   │   ├── java
│   │   │   └── com
│   │   │       └── bookkeeping
│   │   │           └── backend
│   │   │               ├── ApisApplication.java
│   │   │               ├── datafetcher
│   │   │               │   ├── AuthorDataFetcher.java
│   │   │               │   ├── BookDataFetcher.java
│   │   │               │   └── ReaderDataFetcher.java
│   │   │               ├── model
│   │   │               │   ├── Author.java
│   │   │               │   ├── Book.java
│   │   │               │   └── Reader.java
│   │   │               └── repository
│   │   │                   ├── AuthorRepository.java
│   │   │                   ├── BookRepository.java
│   │   │                   └── ReaderRepository.java
│   │   └── resources
│   │       └── graphql-client
│   │           └── schema.graphqls
│   └── test
│       └── java
│           └── com
│               └── bookkeeping
│                   └── backend
│                       └── ApisApplicationTests.java
└── README.md

GraphQL Schema

The GraphQL schema is defined in src/main/resources/graphql-client/schema.graphqls:

type Query {
    books: [Book]
    authors: [Author]
    readers: [Reader]
}

type Mutation {
    addBook(title: String, authorId: ID): Book
    addAuthor(name: String): Author
    addReader(name: String): Reader
}

type Book {
    id: ID
    title: String
    author: Author
}

type Author {
    id: ID
    name: String
}

type Reader {
    id: ID
    name: String
}

Data Fetchers

AuthorDataFetcher

Handles queries and mutations related to authors.

package com.bookkeeping.backend.apis.datafetcher;

import com.bookkeeping.backend.apis.model.Author;
import com.bookkeeping.backend.apis.repository.AuthorRepository;
import com.netflix.graphql.dgs.DgsComponent;
import com.netflix.graphql.dgs.DgsData;
import com.netflix.graphql.dgs.InputArgument;
import org.springframework.beans.factory.annotation.Autowired;

import java.util.List;

@DgsComponent
public class AuthorDataFetcher {

    @Autowired
    private AuthorRepository authorRepository;

    @DgsData(parentType = "Query", field = "authors")
    public List<Author> getAuthors() {
        return authorRepository.findAll();
    }

    @DgsData(parentType = "Mutation", field = "addAuthor")
    public Author addAuthor(@InputArgument String name) {
        Author author = new Author();
        author.setName(name);
        return authorRepository.save(author);
    }
}

BookDataFetcher

Handles queries and mutations related to books.

package com.bookkeeping.backend.apis.datafetcher;

import com.bookkeeping.backend.apis.model.Author;
import com.bookkeeping.backend.apis.model.Book;
import com.bookkeeping.backend.apis.repository.AuthorRepository;
import com.bookkeeping.backend.apis.repository.BookRepository;
import com.netflix.graphql.dgs.DgsComponent;
import com.netflix.graphql.dgs.DgsData;
import com.netflix.graphql.dgs.InputArgument;
import org.springframework.beans.factory.annotation.Autowired;

import java.util.List;

@DgsComponent
public class BookDataFetcher {

    @Autowired
    private BookRepository bookRepository;

    @Autowired
    private AuthorRepository authorRepository;

    @DgsData(parentType = "Query", field = "books")
    public List<Book> getBooks() {
        return bookRepository.findAll();
    }

    @DgsData(parentType = "Mutation", field = "addBook")
    public Book addBook(@InputArgument String title, @InputArgument Long authorId) {
        Author author = authorRepository.findById(authorId).orElseThrow(() -> new RuntimeException("Author not found"));
        Book book = new Book();
        book.setTitle(title);
        book.setAuthor(author);
        return bookRepository.save(book);
    }
}

ReaderDataFetcher

Handles queries and mutations related to readers.

package com.bookkeeping.backend.apis.datafetcher;

import com.bookkeeping.backend.apis.model.Reader;
import com.bookkeeping.backend.apis.repository.ReaderRepository;
import com.netflix.graphql.dgs.DgsComponent;
import com.netflix.graphql.dgs.DgsData;
import com.netflix.graphql.dgs.InputArgument;
import org.springframework.beans.factory.annotation.Autowired;

import java.util.List;

@DgsComponent
public class ReaderDataFetcher {

    @Autowired
    private ReaderRepository readerRepository;

    @DgsData(parentType = "Query", field = "readers")
    public List<Reader> getReaders() {
        return readerRepository.findAll();
    }

    @DgsData(parentType = "Mutation", field = "addReader")
    public Reader addReader(@InputArgument String name) {
        Reader reader = new Reader();
        reader.setName(name);
        return readerRepository.save(reader);
    }
}

Testing the API

Visit http://localhost:9191/graphiql to interact with the GraphQL API. You can use the following queries and mutations for testing:

Queries

{
  books {
    id
    title
    author {
      id
      name
    }
  }
  authors {
    id
    name
  }
  readers {
    id
    name
  }
}

Mutations

mutation {
  addBook(title: "New Book", authorId: 1) {
    id
    title
  }
  addAuthor(name: "New Author") {
    id
    name
  }
  addReader(name: "New Reader") {
    id
    name
  }
}

License

This project is licensed under the MIT License.