Getting Started with GraphQL in Spring Boot

GraphQL is a query language for APIs, and it’s a powerful alternative to REST. Spring Boot, combined with the Spring GraphQL module, makes it easy to create GraphQL-based APIs.

Prerequisites:

• Basic knowledge of Spring Boot and Java.
• JDK 8 or later installed on your machine.
• An Integrated Development Environment (IDE) such as IntelliJ IDEA or Eclipse.

Let’s go through the steps:

Step 1: Set Up a Spring Boot Project

Create a new Spring Boot project using your preferred method (Spring Initializer or your IDE). Include the “Spring Web” and “Spring Data JPA” dependencies.

Step 2: Add GraphQL Dependencies

Open your project’s pom.xml file and add the necessary dependencies for GraphQL. Here’s an example:

<dependencies>
    <!-- Spring Boot Starter Web -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

    <!-- Spring Data JPA -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>

    <!-- GraphQL Dependencies -->
    <dependency>
        <groupId>com.graphql-java-kickstart</groupId>
        <artifactId>graphql-spring-boot-starter</artifactId>
        <version>11.1.0</version> <!-- Check for the latest version -->
    </dependency>
</dependencies>

Step 3: Create GraphQL Schema

Create a GraphQL schema in a file named schema.graphqls in the src/main/resources folder. This file defines your GraphQL types, queries, and mutations. Here’s an example:

Step 4: Create Entities and Repositories

Create a Book entity and a corresponding repository. For example:

Step 5: Create GraphQL Resolvers

Create resolvers that handle GraphQL queries and mutations. Create a class named GraphQLResolver:

Step 6: Run the Application

Run your Spring Boot application. By default, the GraphQL endpoint will be available at http://localhost:8080/graphql. You can access this URL using tools like GraphiQL or Insomnia.

Step 7: Test GraphQL Queries and Mutations

Open your GraphQL tool and try out some queries and mutations:

# Query to get all books
query {
  getAllBooks {
    id
    title
    author
  }
}

# Query to get a book by ID
query {
  getBookById(id: 1) {
    id
    title
    author
  }
}

# Mutation to add a new book
mutation {
  addBook(title: "Spring Boot GraphQL", author: "John Doe") {
    id
    title
    author
  }
}

That’s it! You’ve successfully created a Spring Boot application with GraphQL support. You can extend this example by adding more entities, queries, and mutations based on your application’s requirements.