How to create Search Functionality using Optional Parameter in Spring Boot - spring

Question

I want to build a search functionality in my application. There are many parameters which can be optional.
Model
#Getter
#Setter
#EqualsAndHashCode(exclude = "inventoryInspectionReport")
#NoArgsConstructor
#Entity()
public class Inventory {
#SequenceGenerator(
name = "car_inventory_sequence",
sequenceName = "car_inventory_sequence",
allocationSize = 1
)
#Id
#GeneratedValue(
strategy = GenerationType.SEQUENCE,
generator = "car_inventory_sequence"
)
private Long id;
#Column(nullable = false)
private String name;
#Column(nullable = false)
private String owner;
#Column(nullable = false)
private String km_driven;
#Column(nullable = false)
private Integer price;
#Column
private String fuelType;
#Column
private String location;
#Column
private String insuranceValidity;
#Column
private String rto;
}
Controller
#GetMapping("/buy-car")
public String showBuyCarPageList(Model model,
#RequestParam("page") Optional<Integer> page,
#RequestParam("size") Optional<Integer> size
){
int currentPage = page.orElse(1);
int pageSize = size.orElse(16);
Page<Inventory> pageObj = carInventoryService.listAllCarIfShow(currentPage, pageSize);
int totalPages = pageObj.getTotalPages();
long totalItems = pageObj.getTotalElements();
List<Inventory> carInventoryList = pageObj.getContent();
model.addAttribute("currentPage", 1);
model.addAttribute("totalPages", totalPages);
model.addAttribute("totalItems", totalItems);
model.addAttribute("carInfo", carInventoryList);
return "frontend/buy-car-list";
}
#Service
#AllArgsConstructor
public class InventoryServiceImpl implements InventoryService {
#Autowired
private Environment env;
InventoryRepository carInventoryRepository;
InventoryImagesRepository carInventoryImagesRepository;
#Override
public Page<Inventory> listAllCarIfShow(int pageNumber, int pageSize) {
Pageable pageable = PageRequest.of(pageNumber - 1, pageSize);
return carInventoryRepository.findAllByShow(true, pageable);
}
}
My question is, how i can create a search functionality? There can be some parameter null? How i can query or ignore the parameters?
Bellow is query samples
http://localhost:8080/buy-car?page=1&size=1&name=Car2
http://localhost:8080/buy-car?page=1&size=1&name=Car2&owner=1st
http://localhost:8080/buy-car?page=1&size=1&fuelType=Petrol&owner=1st
Sample form image

Answer 1

Assuming that you are using JPA. You can handle it by writing a query as below. This will ignore the where condition if the parameter is null.
#Repository
public class InventoryRepository extends JPARepository<Inventory, Long> {
#Query("SELECT i FROM Inventory i WHERE (:name is null or i.name = :name) and (:owner is null or i.owner = :owner)")
Page<Inventory> findAllByShow (String name, String owner, Pageable pageable);
}
PS: You need to update your Controller and Service layers to accept other parameters such as name, owner etc..