添加 orderBy 排序到搜索规范

Question

我想通过按参数添加顺序来扩展本规范。

搜索选项 DTO：

public class ProductSearchParams {
    private String title;
    private String type;
    private LocalDateTime publishedAt;
    private String sort;
    private List<String> sortBy;
}

public Page<ProductFullDTO> findProducts(ProductSearchParams params, Pageable pageable) {
        Specification<Product> spec = (root, query, cb) -> {
            List<Predicate> predicates = new ArrayList<>();
            if (params.getTitle() != null) {
                predicates.add(cb.equal(root.get("title"), params.getTitle()));
            }
            if (params.getType() != null) {
                predicates.add(cb.equal(root.get("type"), params.getType()));
            }
            if (params.getPublishedAt() != null) {
                predicates.add(cb.greaterThan(root.get("publishedAt"), params.getPublishedAt()));
            }
            return cb.and(predicates.toArray(new Predicate[predicates.size()]));
        };
        return productService.findAll(spec, pageable).map(productMapper::toFullDTO);
    }

我试过了：

public Page<ProductFullDTO> findProducts(ProductSearchParams params, Pageable pageable) {
        Specification<Product> spec = (root, query, cb) -> {
            List<Predicate> predicates = new ArrayList<>();
            if (params.getTitle() != null) {
                predicates.add(cb.equal(root.get("title"), params.getTitle()));
            }
            if (params.getType() != null) {
                predicates.add(cb.equal(root.get("type"), params.getType()));
            }
            if (params.getPublishedAt() != null) {
                predicates.add(cb.greaterThan(root.get("publishedAt"), params.getPublishedAt()));
            }
            if (params.getPublishedAt() != null) {
                predicates.add(cb.greaterThan(root.get("publishedAt"), params.getPublishedAt()));
            }
            query.orderBy(builder.desc((root.join(Prodotto_.listaQuoteIng))
                    .get(QuotaIngrediente_.perc_ing)));

            return cb.and(predicates.toArray(new Predicate[predicates.size()]));
        };
        return productService.findAll(spec, pageable).map(productMapper::toFullDTO);
    }

我找不到如何实现这一点的解决方案。你能在我错的地方给我建议吗？

Answer 1

在调用findAll方法之前重新创建pageable对象：

// sort = "desc" sortBy = ["listaQuoteIng.perc_ing"]
List<Sort.Order> orders = params.getSortBy().stream().map(s -> new Sort.Order("asc".equals(params.getSort()) ? ASC : DESC, s)).collect(Collectors.toList());
pageable = new PageRequest(pageable.getPageNumber(), pageable.getPageSize(), new Sort(orders));

Answer 2

您是在问如何使用sortBy 列表来指定排序顺序？以下应该有效：

query.orderBy(sortyBy.stream()
    .map(root::get)
    .map(cb::desc)
    .toList());

您还可以通过sort 查询参数（例如sort=name,asc&sort=type,desc&sort=listaQuoteIng.perc_ing,desc）将排序顺序传递给Pageable，并轻松地将其调整为Criteria API，请参阅this answer。