Student CRUD Application

A complete Student Management System built with Spring Boot, demonstrating all CRUD (Create, Read, Update, Delete) operations with proper validation, error handling, and best practices.

🚀 Features

• Complete CRUD Operations for Student management
• Input Validation with detailed error messages
• Global Exception Handling for consistent error responses
• Sample Data Initialization for testing
• H2 In-Memory Database for development
• RESTful API Design following best practices
• Comprehensive Logging for debugging
• Unit Tests for controllers
• Detailed Code Comments for beginners

📁 Project Structure

src/
├── main/
│   ├── java/com/example/demo/
│   │   ├── DemoApplication.java          # Main Spring Boot application class
│   │   ├── config/
│   │   │   └── DataInitializer.java      # Sample data initialization
│   │   ├── controller/
│   │   │   └── StudentController.java    # REST API endpoints
│   │   ├── dto/
│   │   │   ├── StudentRequestDTO.java    # Request data transfer object
│   │   │   └── StudentResponseDTO.java   # Response data transfer object
│   │   ├── entity/
│   │   │   └── Student.java              # JPA entity for database
│   │   ├── exception/
│   │   │   ├── ErrorResponse.java        # Error response structure
│   │   │   ├── GlobalExceptionHandler.java # Global error handling
│   │   │   └── ValidationErrorResponse.java # Validation error structure
│   │   ├── repository/
│   │   │   └── StudentRepository.java    # Data access layer
│   │   └── service/
│   │       ├── StudentService.java       # Business logic interface
│   │       └── impl/
│   │           └── StudentServiceImpl.java # Business logic implementation
│   └── resources/
│       └── application.properties        # Application configuration
└── test/
    └── java/com/example/demo/
        └── controller/
            └── StudentControllerTest.java # Unit tests for controller

🛠️ Technologies Used

• Java 17 - Programming language
• Spring Boot 3.5.7 - Framework
• Spring Data JPA - Database access
• Spring Boot Validation - Input validation
• H2 Database - In-memory database
• Lombok - Reduces boilerplate code
• Maven - Build tool
• JUnit 5 - Testing framework

🏃‍♂️ Running the Application

Prerequisites

• Java 17 or higher
• Maven (or use included Maven wrapper)

Steps to Run

1. Clone or download the project

2. Navigate to project directory

   cd demo

3. Run the application

   ./mvnw spring-boot:run

4. Application will start on port 8080

   http://localhost:8080
   

5. Access H2 Database Console (optional)

   http://localhost:8080/h2-console
   

   • JDBC URL: jdbc:h2:mem:studentdb
   • Username: sa
   • Password: (leave empty)

📝 API Documentation

Base URL: http://localhost:8080/api/students

Sample Data

The application automatically creates 5 sample students:

• John Doe (Computer Science, Active)
• Jane Smith (Business Administration, Active)
• Mike Johnson (Engineering, Active)
• Emily Davis (Psychology, Inactive)
• David Wilson (Computer Science, Active)

---

🔄 CRUD Operations

1. CREATE - Add New Student

Endpoint: POST /api/students

Request Body:

{
  "firstName": "Alice",
  "lastName": "Brown",
  "email": "alice.brown@email.com",
  "age": 21,
  "course": "Mathematics",
  "phoneNumber": "1111222233",
  "dateOfBirth": "2002-06-15",
  "address": "123 University Ave",
  "isActive": true
}

Response (201 Created):

{
  "id": 6,
  "firstName": "Alice",
  "lastName": "Brown",
  "fullName": "Alice Brown",
  "email": "alice.brown@email.com",
  "age": 21,
  "course": "Mathematics",
  "phoneNumber": "1111222233",
  "dateOfBirth": "2002-06-15",
  "address": "123 University Ave",
  "isActive": true
}

cURL Command:

curl -X POST http://localhost:8080/api/students \
  -H "Content-Type: application/json" \
  -d '{
    "firstName": "Alice",
    "lastName": "Brown",
    "email": "alice.brown@email.com",
    "age": 21,
    "course": "Mathematics",
    "phoneNumber": "1111222233",
    "dateOfBirth": "2002-06-15",
    "address": "123 University Ave",
    "isActive": true
  }'

---

2. READ - Get All Students

Endpoint: GET /api/students

Response (200 OK):

[
  {
    "id": 1,
    "firstName": "John",
    "lastName": "Doe",
    "fullName": "John Doe",
    "email": "john.doe@email.com",
    "age": 20,
    "course": "Computer Science",
    "phoneNumber": "1234567890",
    "dateOfBirth": "2003-05-15",
    "address": "123 Main Street, City, State",
    "isActive": true
  }
  // ... more students
]

cURL Command:

curl -X GET http://localhost:8080/api/students

---

3. READ - Get Student by ID

Endpoint: GET /api/students/{id}

Response (200 OK):

{
  "id": 1,
  "firstName": "John",
  "lastName": "Doe",
  "fullName": "John Doe",
  "email": "john.doe@email.com",
  "age": 20,
  "course": "Computer Science",
  "phoneNumber": "1234567890",
  "dateOfBirth": "2003-05-15",
  "address": "123 Main Street, City, State",
  "isActive": true
}

cURL Command:

curl -X GET http://localhost:8080/api/students/1

---

4. UPDATE - Update Student

Endpoint: PUT /api/students/{id}

Request Body:

{
  "firstName": "John",
  "lastName": "Doe",
  "email": "john.doe.updated@email.com",
  "age": 21,
  "course": "Computer Science",
  "phoneNumber": "1234567890",
  "dateOfBirth": "2003-05-15",
  "address": "456 Updated Street",
  "isActive": true
}

Response (200 OK):

{
  "id": 1,
  "firstName": "John",
  "lastName": "Doe",
  "fullName": "John Doe",
  "email": "john.doe.updated@email.com",
  "age": 21,
  "course": "Computer Science",
  "phoneNumber": "1234567890",
  "dateOfBirth": "2003-05-15",
  "address": "456 Updated Street",
  "isActive": true
}

cURL Command:

curl -X PUT http://localhost:8080/api/students/1 \
  -H "Content-Type: application/json" \
  -d '{
    "firstName": "John",
    "lastName": "Doe",
    "email": "john.doe.updated@email.com",
    "age": 21,
    "course": "Computer Science",
    "phoneNumber": "1234567890",
    "dateOfBirth": "2003-05-15",
    "address": "456 Updated Street",
    "isActive": true
  }'

---

5. DELETE - Delete Student

Endpoint: DELETE /api/students/{id}

Response: 204 No Content

cURL Command:

curl -X DELETE http://localhost:8080/api/students/1

---

🔍 Search Operations

Get Student by Email

curl -X GET http://localhost:8080/api/students/email/john.doe@email.com

Get Students by Course

curl -X GET http://localhost:8080/api/students/course/Computer%20Science

Get Active Students Only

curl -X GET http://localhost:8080/api/students/active

Get Inactive Students Only

curl -X GET http://localhost:8080/api/students/inactive

Search Students by Name

curl -X GET "http://localhost:8080/api/students/search?name=John"

Get Students by Age Range

curl -X GET "http://localhost:8080/api/students/age-range?minAge=18&maxAge=25"

---

🔧 Utility Operations

Update Student Status (Activate/Deactivate)

curl -X PATCH "http://localhost:8080/api/students/1/status?isActive=false"

Check if Email Exists

curl -X GET "http://localhost:8080/api/students/email-exists?email=john.doe@email.com"

Get Student Count by Course

curl -X GET http://localhost:8080/api/students/course/Computer%20Science/count

Get Active Student Count

curl -X GET http://localhost:8080/api/students/active/count

---

❌ Error Handling

The application provides detailed error responses for various scenarios:

Validation Error (400 Bad Request)

{
  "timestamp": "2025-11-03T10:30:00",
  "status": 400,
  "error": "Validation Failed",
  "message": "Input validation failed",
  "validationErrors": {
    "firstName": "First name is required",
    "email": "Please provide a valid email address",
    "age": "Age must be at least 15"
  },
  "path": "/api/students"
}

Student Not Found (400 Bad Request)

{
  "timestamp": "2025-11-03T10:30:00",
  "status": 400,
  "error": "Bad Request",
  "message": "Student not found with ID: 999",
  "path": "/api/students"
}

Email Already Exists (400 Bad Request)

{
  "timestamp": "2025-11-03T10:30:00",
  "status": 400,
  "error": "Bad Request",
  "message": "Student with email john.doe@email.com already exists",
  "path": "/api/students"
}

---

🧪 Testing

Run Unit Tests

./mvnw test

Run Specific Test Class

./mvnw test -Dtest=StudentControllerTest

---

🎯 Learning Objectives Covered

This project demonstrates key concepts for beginners:

1. Spring Boot Basics - Auto-configuration, annotations, dependency injection
2. REST API Development - HTTP methods, status codes, request/response handling
3. Data Persistence - JPA entities, repositories, database operations
4. Input Validation - Bean validation, custom validators
5. Error Handling - Global exception handlers, custom error responses
6. Testing - Unit tests, mocking, test-driven development
7. Project Structure - Layered architecture, separation of concerns
8. Best Practices - Code organization, naming conventions, documentation

---

📚 Key Concepts Explained

1. Layered Architecture

• Controller Layer - Handles HTTP requests/responses
• Service Layer - Contains business logic
• Repository Layer - Handles data access
• Entity Layer - Represents database tables

2. Data Transfer Objects (DTOs)

• RequestDTO - Data coming from client
• ResponseDTO - Data going to client
• Separates API structure from database structure

3. Dependency Injection

• Spring automatically provides required dependencies
• @Autowired, @RequiredArgsConstructor handle injection

4. JPA Repositories

• Automatic CRUD operations
• Custom query methods
• No implementation needed (Spring provides it)

5. Validation Annotations

• @NotBlank, @NotNull, @Email, @Min, @Max
• Automatic validation with @Valid

---

🚧 Future Enhancements

• Add pagination and sorting
• Implement security with JWT
• Add file upload for student photos
• Create a frontend with React/Angular
• Add email notifications
• Implement audit logging
• Add Docker containerization

---

🤝 Contributing

Feel free to submit issues and enhancement requests!

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📄 License

This project is for educational purposes.