CODEWITHSUNDEEP
hibernatejpadefault-valuemany-to-one
Nicolas Trichet
Nicolas Trichet

Reputation: 204

ManyToOne default value

I have an application with default values persisted in the database. For example, a class Person with an attribute City wich default is "New York" with the id 0.

@Entity
public class Person {
  @Id
  private Integer personId;

  private String name;

  @ManyToOne
  private City city;
}

@Entity
public class City {
  @Id
  private Integer cityId;

  private String cityName;
}

And in database :

+--------+------------+
| cityId | cityName   |
+--------+------------+
|      0 | 'New York' |
+--------+------------+

And what I want to do is to save a new Person :

Person p = new Person();
p.setName("Smith");
personRepository.save(p);

If i try to create a city instance whith id 0 and name "New York" I will have a "TransientObjectException: object references an unsaved transient instance" : definitely not a good solution.

If I put a default value in the table definition I will have to reload entity from database after saving it.

I could load the city before saving the Person, but I will have also 2 access to the database.

These two solutions are not good for me because I have to explicitely load City instance from database. Is there a way to do it automatically ? (maybe an interceptor or something like that)

NB: I use hibernate 4 and spring 3.2

Upvotes: 0

Views: 1010

Answers (1)

axtavt
axtavt

Reputation: 242686

If i try to create a city instance whith id 0 and name "New York" I will have a "TransientObjectException: object references an unsaved transient instance"

It should not be so. Perhaps it's caused by the fact that id of default city is 0. Try to use 1 instead.

Alternatively, you can obtain a lazy proxy without touching the database using Session.load()/EntityManager.getReference().

Upvotes: 1

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