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Build a complete CRUD application with Spring Boot - project setup, layered architecture, full CRUD operations, testing, and deployment.
Project Overview
We'll build a complete Employee Management System REST API with:
- Full CRUD operations (Create, Read, Update, Delete)
- Input validation
- Exception handling
- Pagination and sorting
- DTO pattern
- Service layer with business logic
Testing with Postman/cURL
bash example
# Create Employee
curl -X POST http://localhost:8080/api/v1/employees \
-H "Content-Type: application/json" \
-d '{"firstName":"John","lastName":"Doe","email":"john@example.com","department":"IT","salary":75000}'
# Get All Employees (paginated)
curl "http://localhost:8080/api/v1/employees?page=0&size=5&sortBy=salary&direction=desc"
# Get Employee by ID
curl http://localhost:8080/api/v1/employees/1
# Update Employee
curl -X PUT http://localhost:8080/api/v1/employees/1 \
-H "Content-Type: application/json" \
-d '{"firstName":"John","lastName":"Smith","email":"john@example.com","department":"Engineering","salary":85000}'
# Delete Employee
curl -X DELETE http://localhost:8080/api/v1/employees/1Interview Key Points
- CRUD = Create (POST), Read (GET), Update (PUT), Delete (DELETE)
- Always use DTOs to separate API contract from internal model
- Validate input with
@Valid+ Jakarta validation annotations - Use
@Transactionalfor write operations - Return proper HTTP status codes (201 Created, 404 Not Found, etc.)
- Implement global exception handling with
@RestControllerAdvice - Add pagination for list endpoints to handle large datasets
- Use Builder pattern for clean object construction
Summary
In this chapter, we learned about CRUD Application with Spring Boot in detail. Here are the key points:
- Basic introduction to the concept and why it is needed
- Syntax and structure with complete examples
- Internal working and best practices
- Real-world applications and use cases
- Common mistakes and how to avoid them
- How this topic is asked in interviews
To practice these concepts, write and run the code in your IDE and verify the output. Modify each example and experiment so that you deeply understand the concept.
Continue the lesson path
Study next in this module
01Spring FrameworkSpring Data JPAComplete guide to Spring Data JPA - entity mapping, repository interfaces, query methods, JPQL, native queries, relationships, and database operations.02Spring FrameworkValidation in Spring BootComplete guide to input validation in Spring Boot - Jakarta Bean Validation, custom validators, group validation, and validation error handling.03Spring FrameworkException Handling in Spring BootComplete guide to exception handling in Spring Boot - @ExceptionHandler, @ControllerAdvice, custom exceptions, error responses, and validation error handling.04Spring FrameworkREST API with Spring BootBuilding RESTful APIs with Spring Boot - REST principles, controller annotations, request/response handling, pagination, HATEOAS, and API versioning.