usmanwalana :
I am new to Spring and MapStruct. I am having issues with conversion from Page to List. I used the MapStruct mapper in the service. I need to fetch all products from DB, then convert to ProductResponse using MapStruct mapper and then return PagedResponse object but the following error appears:
java.lang.ClassCastException: org.springframework.data.domain.PageImpl cannot be cast to java.util.List
at org.walana.GP.service.ProductService.getAll(ProductService.java:67) ~[classes/:na]
at org.walana.GP.controller.ProductController.getAll(ProductController.java:40)
ReplaceNumber
@Entity
@Table(name = "replace_numbers")
public class ReplaceNumber extends UserDateAudit
{
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@NotBlank
@Size(max = 20)
private String partNumber;
@ManyToOne(fetch = FetchType.LAZY, optional = false)
@JoinColumn(name = "product_id", nullable = false)
private Product product;
public ReplaceNumber() {}
public ReplaceNumber(String partNumber)
{
this.partNumber = partNumber;
}
}
ReplaceNumberResponse
public class ReplaceNumberResponse
{
private Long id;
private String partNumber;
}
Product
@Entity
@Table(name = "products", indexes = {@Index(name= "part_number_index", columnList = "part_number", unique = true)})
public class Product extends UserDateAudit
{
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@NotBlank
@Column(name = "part_number", nullable = false)
@Size(max = 20)
private String partNumber;
@NotBlank
@Size(max = 255)
private String description;
@OneToMany(
mappedBy = "product",
cascade = CascadeType.ALL,
fetch = FetchType.EAGER,
orphanRemoval = true
)
@Fetch(FetchMode.SELECT)
private List<ReplaceNumber> replaceNumbers = new ArrayList<>();
@ManyToOne
@JoinColumn(name = "product_manufacturer_id", referencedColumnName = "id")
private ProductManufacturer manufacturer;
@ManyToOne
@JoinColumn(name = "product_model_id", referencedColumnName = "id")
private ProductModel model;
@ManyToOne
@JoinColumn(name = "product_category_id", referencedColumnName = "id")
private ProductCategory category;
@Column(name = "cost", nullable = false)
@DecimalMin(message = "Cost should be greater than 1", value = "1")
private float cost;
@Column(name = "price", nullable = false)
@DecimalMin(message = "Price should be greater than 0", value = "0")
private float price;
}
ProductResponse
public class ProductResponse
{
private Long id;
private String partNumber;
private String description;
private List<ReplaceNumberResponse> replaceNumberResponses;
private ProductManufacturerResponse manufacturer;
private ProductModelResponse model;
private ProductCategoryResponse category;
private float cost;
private float price;
}
ProductMapper
@Mapper(componentModel = "spring")
public interface ProductMapper
{
ProductResponse toProductResponse(Product product);
List<ProductResponse> toProductResponses(List<Product> products);
Product toProduct(ProductResponse productResponse);
}
PagedResponse
public class PagedResponse<T>
{
private List<T> content;
private int page;
private int size;
private long totalElements;
private int totalPages;
private boolean last;
public PagedResponse() {
}
public PagedResponse(List<T> content, int page, int size, long totalElements, int totalPages, boolean last) {
this.content = content;
this.page = page;
this.size = size;
this.totalElements = totalElements;
this.totalPages = totalPages;
this.last = last;
}
}
ProductService
@Service
public class ProductService
{
@Autowired
ProductRepository productRepository;
@Autowired
ProductMapper productMapper;
public PagedResponse<ProductResponse> getAll(UserPrincipal currentUser, int page, int size)
{
Pageable pageable = PageRequest.of(page, size, Sort.Direction.DESC, "createdAt");
Page<Product> products = productRepository.findAll(pageable);
if (products.getNumberOfElements() == 0)
{
return new PagedResponse<>(Collections.emptyList(), products.getNumber(),
products.getSize(), products.getTotalElements(), products.getTotalPages(), products.isLast());
}
List<ProductResponse> productResponses = productMapper.toProductResponses((List<Product>) products);
return new PagedResponse<>(productResponses, products.getNumber(),
products.getSize(), products.getTotalElements(), products.getTotalPages(), products.isLast());
}
}
ProductController
@RestController
@RequestMapping("/api/products")
public class ProductController
{
@Autowired
private ProductService productService;
private static final Logger logger = LoggerFactory.getLogger(ProductController.class);
@GetMapping
public PagedResponse<ProductResponse> getAll(@CurrentUser UserPrincipal currentUser,
@RequestParam(value = "page", defaultValue = AppConstants.DEFAULT_PAGE_NUMBER) int page,
@RequestParam(value = "size", defaultValue = AppConstants.DEFAULT_PAGE_SIZE) int size)
{
return productService.getAll(currentUser, page, size);
}
}
Nikolai Shevchenko :
Replace
productMapper.toProductResponses((List<Product>) products)
with
productMapper.toProductResponses(products.getContent())
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