java 41 lines · 8 steps

How a paginated REST controller works in Spring

A Spring REST controller exposes paginated, filterable product listings and maps entities to clean response DTOs.

Explained by highlit
Spring Intermediate pagination dto-mapping dependency-injection rest-api optional-chaining
1@RestController
2@RequestMapping("/api/products")
3public class ProductController {
4 
5 private final ProductRepository productRepository;
6 
7 public ProductController(ProductRepository productRepository) {
8 this.productRepository = productRepository;
9 }
10 
11 @GetMapping
12 public Page<ProductResponse> listProducts(
13 @RequestParam(required = false) String category,
14 @PageableDefault(size = 20, sort = "createdAt", direction = Sort.Direction.DESC)
15 Pageable pageable) {
16 
17 Page<Product> products = (category == null || category.isBlank())
18 ? productRepository.findAll(pageable)
19 : productRepository.findByCategoryIgnoreCase(category, pageable);
20 
21 return products.map(ProductResponse::from);
22 }
23 
24 @GetMapping("/{id}")
25 public ResponseEntity<ProductResponse> getProduct(@PathVariable Long id) {
26 return productRepository.findById(id)
27 .map(ProductResponse::from)
28 .map(ResponseEntity::ok)
29 .orElseGet(() -> ResponseEntity.notFound().build());
30 }
31 
32 public record ProductResponse(Long id, String name, String category, BigDecimal price) {
33 static ProductResponse from(Product product) {
34 return new ProductResponse(
35 product.getId(),
36 product.getName(),
37 product.getCategory(),
38 product.getPrice());
39 }
40 }
41}
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1Mapping entities to dedicated response records keeps your API contract decoupled from your persistence model.
  2. 2Spring's Pageable and @PageableDefault hand you paging and sorting from query parameters with almost no code.
  3. 3Returning ResponseEntity lets a single handler express both success and 404 outcomes cleanly.

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