I was reading this book. Explaing about "@OneToOne unidirectional", the author has taken the following Customer, Address example:
@Entity
public class Customer{
@Id @GeneratedValue
private Long id;
private String name;
private Address address;
//few other columns, getters/setters
}
@Entity
public class Address{
@Id @GeneratedValue
private Long id;
private String city;
//few other columns, getters/setters
}
And was saying that -
- This is the minimum required annotaions.
- No @OneToOne annotaion is needed.(Because, by default, the persistance provider will assume it)
- The @JoinColumn annotation allows you to customize the mapping of a foreign key. As show below, we can RENAME the foreign key column to ADD_FK
And then about this one:
@Entity
public class Customer {
@Id @GeneratedValue
private Long id;
private String name;
@OneToOne
@JoinColumn(name="ADD_FK")
private Address address;
//few other columns, getters/setters
}
@Entity
public class Order {
....
List<OrderLine> orderLines;
...
}
- By default, OneToMany relationship is assumend when the collection of an entity type is being used.
My questions:
Are the above statements Valid? Because when I try these examples on Hibernate, I was getting exceptions.
Does the statements are made as per the JPA standards?
- Or is it that Hibernate is implemented differently?
Kindly clarify.