如何为谓词设置连接

Question

我有一个产品实体：

package com.javaschool.entity;

import lombok.*;

import javax.persistence.*;
import java.util.Set;

@EqualsAndHashCode(of = {"id"})
@ToString(of = { "id", "quantity", "price", "model"})
@Entity
@Table(name = "products")
@Data
@NoArgsConstructor
@AllArgsConstructor
public class Product {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;

    @Column(name = "quantity")
    private int quantity;

    @Column(name = "price")
    private int price;

    @Column(name = "model")
    private String model;

    @Column(name = "is_active")
    private boolean active;

    @Column(name = "picture_url")
    private String url;

    @ManyToOne(fetch = FetchType.EAGER, optional = false)
    @JoinColumn(name = "category_id")
    private Category category;

    @ManyToOne(fetch = FetchType.EAGER, optional = false)
    @JoinColumn(name = "brand_id")
    private Brand brand;

    @ManyToOne(fetch = FetchType.EAGER, optional = false)
    @JoinColumn(name = "season_id")
    private Season season;

    @ManyToOne(fetch = FetchType.EAGER, optional = false)
    @JoinColumn(name = "color_id")
    private Color color;

    @ManyToOne(fetch = FetchType.EAGER, optional = false)
    @JoinColumn(name = "material_id")
    private Material material;

    @ManyToOne(fetch = FetchType.EAGER, optional = false)
    @JoinColumn(name = "size_id")
    private Size size;

    @ManyToMany(mappedBy = "productSet", fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.MERGE})
    private Set<Order> orderSet;
}

我要按品类、季节、颜色、品牌等相关参数筛选
目前我的过滤功能是这样的。它适用于型号、价格、数量等参数。也就是说，对于那些在此 table 中而不是其他人的数据。如何按从其他 table 中获取的参数进行过滤？

@Override
    public List<Product> findByParam(List<SearchCriteria> params) {
        CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
        CriteriaQuery<Product> criteriaQuery = criteriaBuilder.createQuery(Product.class);
        Root<Product> root = criteriaQuery.from(Product.class);

        Predicate predicate = criteriaBuilder.conjunction();

        ProductSearchQueryCriteriaConsumer productConsumer = new ProductSearchQueryCriteriaConsumer(predicate, criteriaBuilder, root);

        params.stream().forEach(productConsumer);

        predicate = productConsumer.getPredicate();

        criteriaQuery.where(criteriaBuilder.equal(root.get(Product_.active), true),
                predicate);

        List<Product> result = entityManager.createQuery(criteriaQuery).getResultList();

        return result;
    }

我以为你可以打这样的电话，一切都会好起来的。但是我错了

List<SearchCriteria> params = new ArrayList<SearchCriteria>();
        params.add(new SearchCriteria("season_id", ":", "3"));

        List<ProductDto> productDtoList = productService.getProductsByParam(params);

Answer 1

我的搜索条件

@Data
@AllArgsConstructor
@NoArgsConstructor
public class SearchCriteria {
    private String key;
    private String operation;
    private Object value;
}

需要做这个：

    List<SearchCriteria> params = new ArrayList<SearchCriteria>();
    params.add(new SearchCriteria("category", ":", categoryRepository.findById(1)));

也就是在value对象的searchcriteria中，传一个这个class的对象去filter by

如何为谓词设置连接

How to set join for predicate

spring

hibernate-criteria