Spring Boot GraphQL Demo Project

A comprehensive demonstration of different approaches to implementing GraphQL with Spring Boot, showcasing three popular libraries and their unique features.

🚀 Project Overview

This repository contains three independent Spring Boot applications that demonstrate different approaches to implementing GraphQL APIs. Each application implements the same domain model (Organization → Department → Employee hierarchy) using different GraphQL libraries, allowing for direct comparison of approaches and features.

🔗 Related Articles

1. How to simplify Spring Boot and GraphQL development with GraphQL Kickstart library. The article describes more advanced solution like filtering or joins with a database. The example is available in the branch master. A detailed guide may be found in the following article: An Advanced Guide to GraphQL with Spring Boot
2. How to simplify Spring Boot and GraphQL development with Netflix DGS library. The example is available in the branch master. A detailed guide may be found in the following article: An Advanced GraphQL with Spring Boot and Netflix DGS.
3. How to simplify Spring Boot and GraphQL development with Spring for Graph library. The example is available in the branch master. A detailed guide may be found in the following article: An Advanced GraphQL with Spring Boot.

🏗️ Architecture

graph TB
    A[Organization] --> B[Department]
    B --> C[Employee]
    subgraph GraphQLImplementations ["GraphQL Implementations"]
        D[GraphQL Kickstart]
        E[Netflix DGS]
        F[Spring for GraphQL]
    end
    subgraph DataLayer ["Data Layer"]
        G[JPA/Hibernate]
        H[H2 Database]
    end
    D --> G
    E --> G
    F --> G
    G --> H

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📦 Modules

1. sample-app-kickstart

GraphQL Kickstart Library Implementation

• Uses GraphQL Java Kickstart library
• Resolver-based approach with separate Query and Mutation resolvers
• Built-in GraphiQL interface
• Schema-first development approach

Key Features:

• Schema definition through .graphqls files
• Resolver classes for queries and mutations
• Built-in error handling and validation
• GraphiQL playground at /graphiql

2. sample-app-netflix-dgs

Netflix DGS Framework Implementation

• Uses Netflix DGS (Domain Graph Service) framework
• Annotation-based data fetchers
• Code-first approach with schema generation
• Advanced context and instrumentation support

Key Features:

• @DgsQuery and @DgsMutation annotations
• Built-in testing utilities
• Schema generation from code
• Custom context builder support

3. sample-app-spring-graphql

Spring for GraphQL Implementation

• Uses official Spring GraphQL support
• Controller-based approach similar to Spring MVC
• Integrated with Spring Boot ecosystem
• Schema-first development with annotation mapping

Key Features:

• @QueryMapping and @MutationMapping annotations
• Native Spring Boot integration
• WebMVC and WebFlux support
• Built-in security integration

🗄️ Domain Model

The application models a simple organizational structure:

erDiagram
    Organization ||--o{ Department : contains
    Department ||--o{ Employee : contains
    Organization ||--o{ Employee : employs
    
    Organization {
        int id
        string name
    }
    
    Department {
        int id
        string name
        int organization_id
    }
    
    Employee {
        int id
        string firstName
        string lastName
        string position
        int salary
        int age
        int department_id
        int organization_id
    }

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🔧 Prerequisites

• Java 17 (Java 11 for spring-graphql module)
• Maven 3.6+
• IDE with GraphQL support (IntelliJ IDEA, VS Code with GraphQL extension)

🚀 Quick Start

Clone the Repository

git clone https://github.com/piomin/sample-spring-boot-graphql.git
cd sample-spring-boot-graphql

Build All Modules

mvn clean install

Run Individual Applications

GraphQL Kickstart

cd sample-app-kickstart
mvn spring-boot:run

• GraphQL endpoint: http://localhost:8080/graphql
• GraphiQL interface: http://localhost:8080/graphiql

Netflix DGS

cd sample-app-netflix-dgs
mvn spring-boot:run

• GraphQL endpoint: http://localhost:8080/graphql
• GraphiQL interface: http://localhost:8080/graphiql

Spring for GraphQL

cd sample-app-spring-graphql
mvn spring-boot:run

• GraphQL endpoint: http://localhost:8080/graphql
• GraphiQL interface: http://localhost:8080/graphiql

📊 GraphQL Schema

All three applications implement the same GraphQL schema:

type Query {
    # Organization queries
    organizations: [Organization]
    organization(id: ID!): Organization!
    
    # Department queries
    departments: [Department]
    department(id: ID!): Department!
    
    # Employee queries
    employees: [Employee]
    employee(id: ID!): Employee!
    employeesWithFilter(filter: EmployeeFilter): [Employee]
}

type Mutation {
    # Organization mutations
    newOrganization(organization: OrganizationInput!): Organization
    
    # Department mutations
    newDepartment(department: DepartmentInput!): Department
    
    # Employee mutations
    newEmployee(employee: EmployeeInput!): Employee
}

type Organization {
    id: ID!
    name: String!
    employees: [Employee]
    departments: [Department]
}

type Department {
    id: ID!
    name: String!
    organization: Organization
    employees: [Employee]
}

type Employee {
    id: ID!
    firstName: String!
    lastName: String!
    position: String!
    salary: Int
    age: Int
    department: Department
    organization: Organization
}

input EmployeeFilter {
    salary: FilterField
    age: FilterField
    position: FilterField
}

input FilterField {
    operator: String!  # eq, gt, lt, gte, lte, ne
    value: String!
}

🔍 Example Queries

Query All Organizations with Departments

query {
  organizations {
    id
    name
    departments {
      id
      name
      employees {
        id
        firstName
        lastName
        position
      }
    }
  }
}

Query Employees with Filtering

query {
  employeesWithFilter(filter: {
    salary: { operator: "gt", value: "15000" }
    position: { operator: "eq", value: "Developer" }
  }) {
    id
    firstName
    lastName
    position
    salary
    department {
      name
    }
  }
}

Create New Employee

mutation {
  newEmployee(employee: {
    firstName: "Jane"
    lastName: "Doe"
    position: "Senior Developer"
    salary: 25000
    age: 28
    organizationId: 1
    departmentId: 1
  }) {
    id
    firstName
    lastName
    position
    salary
  }
}

🧪 Testing

Run All Tests

mvn test

Run Tests for Specific Module

cd sample-app-kickstart
mvn test

Test Coverage

mvn jacoco:report

Each module includes comprehensive test coverage for:

• GraphQL query resolvers
• Mutation resolvers
• Filtering functionality
• Error handling

📈 Performance Comparison

Feature	GraphQL Kickstart	Netflix DGS	Spring GraphQL
Learning Curve	Moderate	Steep	Easy (Spring devs)
Performance	Good	Excellent	Good
Community	Active	Growing	Official Spring
Documentation	Comprehensive	Good	Excellent
Testing Support	Good	Excellent	Good
Schema Generation	Schema-first	Code-first	Schema-first
Spring Integration	Good	Excellent	Native

🛠️ Technology Stack

• Framework: Spring Boot 3.x
• Language: Java 17
• Database: H2 (in-memory)
• ORM: JPA/Hibernate
• Build Tool: Maven
• Testing: JUnit 5, Spring Boot Test
• Code Coverage: JaCoCo
• CI/CD: CircleCI
• Code Quality: SonarCloud

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

Development Setup

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Make your changes
4. Run tests (mvn test)
5. Commit your changes (git commit -m 'Add amazing feature')
6. Push to the branch (git push origin feature/amazing-feature)
7. Open a Pull Request

Code Style

• Follow Java coding conventions
• Ensure all tests pass
• Maintain test coverage above 80%
• Update documentation for new features

📝 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙋‍♂️ Support

If you have any questions or need help with the project:

• Create an issue in this repository
• Follow @piotr_minkowski on Twitter
• Check out the related blog articles for detailed explanations

🌟 Acknowledgments

• GraphQL Java Kickstart team
• Netflix DGS team
• Spring GraphQL team
• All contributors to this project