JPA composite primary key [duplicate]

Answer 1

Since you are using @IdClass, the PricePK class need not be marked with the @Embeddable annotation. An example is given in http://www.java2s.com/Code/Java/JPA/SetIdClassforCompoundKey.htm

I tried your code removing the @Embeddable on PricePK class, and the price table generated in MYSQL database with not null fields.

Following is how you could use @EmbeddedId to achieve the required result: (getters and setters omitted)

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
public class Price {

    @EmbeddedId
    PricePK pricePk;
}

@Embeddable
public class PricePK implements Serializable {

    @ManyToOne(optional = false)
    private Product product;

    @ManyToOne(optional = false)
    private Currency currency;
}

Answer 2

Recently I created ManyToMany relation using Composite Primary key and annotation as bi directional @OneToMany. This code works flawless. Maybe it will help:

Mapping ManyToMany with composite Primary key and Annotation: