Backend / SDE
Employee Management REST API
Engineered a production-grade Employee Management REST API with Spring Boot, Spring Data JPA, and MySQL featuring full CRUD operations, request validation, centralized exception handling, pagination, sorting, and unit-tested service layers.
Overview
Challenge
Interviewers expect clean, layered REST services with real validation and error handling, not just a controller that writes to a database.
Solution
Designed a layered Spring Boot architecture (Controller → Service → Repository) with DTOs, Bean Validation, and a global exception handler returning structured error responses.
Status
Production-style SDE Build
Architecture
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Implementation
- Built full CRUD endpoints (GET/POST/PUT/DELETE) with path variable and query parameter routing.
- Enforced Bean Validation constraints (NotNull, Size, Email, Pattern) on request DTOs.
- Implemented a centralized @RestControllerAdvice exception handler mapping validation and not-found errors to RFC 7807-style responses.
- Added pagination and sorting with Spring Data Pageable and wrote JUnit 5 service-layer tests with Mockito.
Results
- Every endpoint returns consistent, well-formed JSON responses with proper HTTP status codes.
- Invalid input is rejected at the boundary before touching business logic or the database.
- Unit tests cover the service layer, validating the interview-relevant separation of concerns.
Lessons Learned
- Layered architecture makes a REST API maintainable and is the first thing senior engineers look for.
- Validation should live on DTOs at the API boundary, never scattered across controllers.
- A single global exception handler keeps error responses uniform across the whole application.
Tech Stack
Java 17Spring BootSpring Data JPAMySQLSpring ValidationJUnit 5