This pull request introduces dynamic filtering, pagination, and sorting for the Department search functionality, enhancing the /api/v1/departments/search endpoint with more flexible and efficient querying capabilities.

🔍 What’s New

Dynamic Filtering: Implemented using Spring Data JPA Specifications, allowing queries based on multiple optional criteria (departmentCode, departmentName, departmentDescription, etc.).

Pagination & Sorting: Integrated pageable and sort functionality to handle large datasets and improve response management.

Code Enhancements:

Added DepartmentSpecification.java for reusable query construction.

Updated DepartmentRepository.java to extend JpaSpecificationExecutor.

Modified DepartmentServiceImpl.java to apply specifications with pagination and sorting.

🧩 Technical Details

Uses CriteriaBuilder and Predicate to build dynamic queries at runtime.

Returns results as Page to maintain consistent response structure.

Backward compatible — no impact on existing Department CRUD operations.

Optimized for maintainability and future extensibility (e.g., filtering by date ranges or relationships).

🧪 How to Test

Run the Spring Boot application.

Open Swagger UI → http://localhost:8080/department-api/swagger-ui/index.html

Navigate to the POST /api/v1/departments/search endpoint.

Try the following example:

{
"departmentCode": "HR",
"departmentName": "eng",
"departmentDescription": "engineer",
"page": 0,
"size": 5,
"sortList": [
{ "field": "departmentName", "direction": "ASC" }
]
}

Verify results are filtered, paginated, and sorted dynamically.

🚀 Benefits

Enables multi-field search without hardcoding queries.

Improves performance and scalability for large datasets.

Makes the API more developer-friendly and extensible.

Follows Spring Boot 3 + Java 21 best practices.

✅ Summary

This PR makes the Department API more powerful and production-ready by introducing a dynamic search system with pagination and sorting, paving the way for advanced enterprise-grade querying capabilities.