外键作为主键注释

Question

There is 2 entity
Product(product_id(PK),product_name..)
Store(product_id(PK,FK),product_quantity,...)

I need @OneToOne, so i do this

public class Product{
  @Id
  @Column(name="PRODUCT_ID")
  @OneToOne(mappedBy="product")
  private int product_id;
  ....
}

public class Store{
  @Id
  @OneToOne(cascade = CascadeType.ALL)
  @JoinColumn(name = "PRODUCT_ID")
  private Product product;
}

Compilier says @Column(s) not allowed on a @OneToOne property: ......shopdb.entity.Product.product_id

What is the problem?

Answer 1

I just moved @OneToOne(mappedBy="product") to new created field in Product

private Store store;

I dont understand how it works correct; Why i need to use 3 fields instead of 2?

Answer 2

You can't mark a column defined with @JoinColumn as @Id . This is applicable only to columns defined with @Column annotation.

It is also a bit strange what are you trying to do. You are basically making the produc_id primary key for both entites, so then why don't make just one?

From what I can see here, I believe that the Store should have a store id property which will be used as primary key.