Snippet

Throwing ResponseStatusException for Missing Entities

ResponseStatusException provides a straightforward, built-in way to handle programmatic errors in Spring REST controllers. By combining it with Java's Optional.orElseThrow, you can cleanly branch control flow and return an HTTP 404 Not Found response when a requested resource does not exist in the database.

snippet.java

java

@RestController
@RequestMapping("/products")
public class ProductController {
    private final ProductRepository repository;
 
    public ProductController(ProductRepository repository) {
        this.repository = repository;
    }
 
    @GetMapping("/{id}")
    public Product getProductById(@PathVariable Long id) {
        return repository.findById(id)
            .orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND, "Product not found"));
    }
}

spring

Breakdown

@GetMapping("/{id}")

Maps HTTP GET requests containing an ID path variable to this handler method.

return repository.findById(id)

Queries the database repository, returning an Optional<Product>.

.orElseThrow(() -> new ResponseStatusException(HttpStatus.NOT_FOUND, "Product not found"));

Extracts the entity if present, or throws a 404 HTTP exception if the Optional is empty.

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Throwing ResponseStatusException for Missing Entities

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