在 JPA 中对具有多对多关系的对象执行 NOT IN QUERY

Question

我有两个 JPA 对象，即 Product 和 Order，它们之间存在多对多关系。

@Entity
@Table(name = "orders")
@JsonInclude(NON_NULL)
public class Order implements Serializable {

    public static final int PRECISION = 2;

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @JsonIgnore
    private String orderId;

    @Column(unique = true, nullable = false, length = 8)
    private String orderNumber;

    @Column
    private BigDecimal discount;

    @Column(nullable = false)
    private BigDecimal taxPercent;

    private BigDecimal total;

    private BigDecimal totalTax;

    private BigDecimal grandTotal;

    @Column(length = 10)
    private String status;

    @ManyToMany(cascade = ALL, fetch = FetchType.EAGER)
    @JoinTable(
            name = "order_product",
            joinColumns = @JoinColumn(name = "order_id", updatable = false, nullable = false),
            inverseJoinColumns = @JoinColumn(name = "product_id", updatable = false, nullable = false)
    )
    private List<Product> products = new ArrayList<>();

    public BigDecimal getTotal() {
        BigDecimal total = new BigDecimal(ZERO);
        if (products == null || products.isEmpty()) {
          return total;
        }
        for (Product product : products) {
            total = total.add(product.getPrice());
        }
        return scaled(total);
    }

    public BigDecimal getTotalTax() {
        return scaled(getTotal().multiply(taxPercent.divide(new BigDecimal("100"))));
    }

    public BigDecimal getGrandTotal() {
        BigDecimal total = this.getTotal().add(getTotalTax());
        if (discount != null) {
            return scaled(total.subtract(discount));
        }
        return scaled(total);
    }

    private BigDecimal scaled(BigDecimal value) {
        return value.setScale(PRECISION, ROUND_FLOOR);
    }

    .. Getters and setters ... 

}

和产品

@Entity
@Table(name = "products")
public class Product implements Serializable {

    @Id
    @GeneratedValue(strategy = IDENTITY)
    @JsonIgnore
    private String productId;

    @Column(unique = true, nullable = false, length = 10)
    private String upc;

    @Column(unique = true, nullable = false, length = 13)
    private String sku;

    @Column(nullable = false)
    private String description;

    @Column(nullable = false)
    private BigDecimal price;

    public BigDecimal getPrice() {
      return price;
    }

    @ManyToMany(mappedBy="products", fetch=FetchType.EAGER)
    @JsonIgnore
    private List<Order> orders = new ArrayList<>();

    // Getters and setters.
}

这是我的 DML

insert into products (product_id, upc, sku, description, price) values ('1', '1257833283', '9394550220002', 'Diva Jeans', 39.99);
insert into products (product_id, upc, sku, description, price) values ('2', '1358743283', '7394650110003', 'Polo Shirt', 19.99);
insert into products (product_id, upc, sku, description, price) values ('3', '1458843283', '7394750120000', 'Floral Swing Skirt', 69.99);
insert into products (product_id, upc, sku, description, price) values ('4', '1358753283', '7394850130001', 'Denim Short', 29.99);
insert into products (product_id, upc, sku, description, price) values ('5', '1258793283', '7394950140000', 'True Skinny Jeans', 49.99);

insert into orders (order_id, order_number, tax_percent, status) values ('1', 'RTL_1001', 10, 'SHIPPED');
insert into orders (order_id, order_number, discount, tax_percent, status) values ('2', 'RTL_1002', 15.55, 10, 'FULFILLED');


insert into order_product (order_id, product_id) values ('1', '1');
insert into order_product (order_id, product_id) values ('1', '2');
insert into order_product (order_id, product_id) values ('2', '2');

我只想选择这样的产品

1. 如果我按不存在的订单查询产品（比如 order_id = 3 不存在），我想返回所有符合条件的产品，因为订单尚未创建。

2. 如果我按确实存在的订单查询产品，那么我希望数据库返回与订单无关的所有产品。例如对于order_id = 1，我希望返回 id = 3、4 和 5 的产品。由于 order_id = 1 已经与 product_id = 1 和 2 相关联，我不希望这些产品被退回。

如果我要编写一个 JDBC SQL 查询

SELECT p.product_id
FROM Product p
WHERE NOT EXISTS 
    (
        SELECT 1 
        FROM order_product 
        WHERE product_id = p.product_id
            AND
            order_id = ?
    )
    OR 
    NOT EXISTS
    (
        SELECT 1 
        FROM order_product 
        WHERE order_id = ?
    )

我不知道如何使用 JPA 创建类似的查询。我能想到的都是这样的。

1. 创建一个继承自 JPARepository 的 ProductRepository

2. 从产品表中获取所有产品，包括 order_product 表中的产品。

3. 使用 JPA 获取给定订单 id 的产品，并从 (2) 中的产品中删除所述产品

我希望有更好的方法来做到这一点。

Answer 1

Order order = em.getReference(Order.class, orderId);
em.createQuery("select distinct p from Product p where :order not member of p.orders")...;