通过OneToMany联接维护订单

Question

I'm using spring boot and want to add a list of products to a page as a foreign key but how can I maintain the ArrayList order when I retrieve from the database? Should I have an intermediate table eg PageProductOrder which maintains product primary key and order column?

@Entity
public class Page {
    @OneToMany
    @JoinColumn(name = "product_id")
    private List<Product> products;

Answer 1

You could do this by using @OrderColumn - this will use a column in the entity for ordering :

@OneToMany
@JoinColumn(name = "product_id")
@OrderColumn(name = "product_index")
private List<Product> products;

The column product_index in Product entity will be used for maintaining order.

Answer 2

You can define the order by using the @OrderBy annotation.

@OneToMany
@JoinColumn(name = "product_id")
@OrderBy(value = "name ASC")
private List<Product> products;